Differential Effects of Etomidate and Midazolam on Vascular Adenosine Triphosphate-sensitive Potassium Channels: Isometric Tension and Patch Clamp Studies.

The aim of this study was to investigate the effects of two imidazoline-derived intravenous anesthetics, etomidate and midazolam, on vascular adenosine triphosphate-sensitive potassium (KATP) channel activity. In isolated rat aorta, isometric tension was recorded to examine the anesthetic effects on vasodilator response to levcromakalim, a selective KATP channel opener. Using the patch clamp method, the anesthetic effects were also examined on the currents through (1) native vascular KATP channels, (2) recombinant KATP channels with different combinations of various types of inwardly rectifying potassium channel (Kir6.0 family: Kir6.1, 6.2) and sulfonylurea receptor (SUR1, 2A, 2B) subunits, (3) SUR-deficient channels derived from a truncated isoform of Kir6.2 subunit (Kir6.2DeltaC36 channels), and (4) mutant Kir6.2DeltaC36 channels with reduced sensitivity to adenosine triphosphate (Kir6.2DeltaC36-K185Q channels). Etomidate (> or = 10 m), but not midazolam (up to 10 m), inhibited the levcromakalim-induced vasodilation, which was sensitive to glibenclamide (IC50: 7.21 x 10 m; maximum inhibitory concentration: 1.22 x 10 m). Etomidate (> or = 3 x 10 m), but not midazolam (up to 10 m), inhibited the native KATP channel activity in both cell-attached and inside-out configurations with IC50 values of 1.68 x 10 m and 1.52 x 10 m, respectively. Etomidate (10 m) also inhibited the activity of various types of recombinant SUR/Kir6.0KATP channels, Kir6.2DeltaC36 channels, and Kir6.2DeltaC36-K185Q channels with equivalent potency. Clinical concentrations of etomidate, but not midazolam, inhibit the KATP channel activity in vascular smooth muscle cells. The inhibition is presumably through its effects on the Kir6.0 subunit, but not on the SUR subunit, with the binding site different from adenosine triphosphate at the amino acid level.


Isoflurane activates sarcolemmal adenosine Triphosphate-sensitive potassium channels in vascular smooth muscle cells: A role of protein kinase A

Recent evidence indicates that vascular adenosine triphosphate-sensitive potassium (K(ATP)) channels in vascular smooth muscle cells are critical in the regulation of vascular tonus under both physiologic and pathophysiologic conditions. Studies of the interaction of volatile anesthetics with vascular K(ATP) channels have been limited. In the current study, the authors investigated the molecular mechanism of isoflurane's action on vascular K(ATP) channels. Electrophysiologic experiments were performed using cell-attached and inside-out patch clamp techniques to monitor native vascular K(ATP) channels, and recombinant K(ATP) channels comprised of inwardly rectifying potassium channel subunits (Kir6.1) and the sulfonylurea receptor (SUR2B). Isometric tension experiments were performed in rat thoracic aortic rings without endothelium. Application of isoflurane (0.5 mM) to the bath solution during cell-attached recordings induced a significant increase in K(ATP) channel activity, which was greatly reduced by pretreatment with a selective inhibitor of protein kinase A (PKA), Rp-cAMPS (100 microM). In inside-out patches, isoflurane did not activate K(ATP) channels. Isoflurane significantly activated wild-type recombinant SUR2B/Kir6.1 in cell-attached patches. Isoflurane-induced activation of wild-type channels was diminished in the PKA-insensitive mutant SUR2B-T633A/Kir6.1, SUR2B-S1465A/Kir6.1, and SUR2B/Kir6.1-S385A. In addition, the authors demonstrated that isoflurane-induced PKA activation was associated with isoflurane-induced decreases in isometric tension in the rat aorta. These results indicate that isoflurane activates K(ATP) channels via PKA activation. PKA-dependent vasodilation induced by isoflurane also was observed in isometric tension experiments. Analysis of expressed vascular-type K(ATP) channels suggested that PKA-mediated phosphorylation of both Kir6.1 and SUR2B subunits plays a pivotal role in isoflurane-induced vascular K(ATP) channel activation.


Bezafibrate improves bacterial lipopolysaccharide-induced dyslipidemia and anorexia in rats.

Bacterial endotoxin/lipopolysaccharide (LPS)-induced cachexia is characterized by weight loss, anorexia, and a disturbance in lipid metabolism, namely, hypertriacylglycerolemia. The aim of this study in rats with acute endotoxicity induced by an injection of LPS was to investigate whether bezafibrate, a ligand for peroxisome proliferator-activated receptor alpha and a lipoprotein lipase (LPL) activator, improved cachectic conditions, including impaired lipid metabolism. Short-term administration of LPS in the rats resulted in impairment of triacylglycerol clearance in plasma after the intake of fresh cream. In addition, LPS increased whole-body energy expenditure, reduced fasting body weight and caused anorexia in the rats. Bezafibrate treatment resulted in significant improvements in LPS-induced dyslipidemia and anorexia, but had no effect on energy expenditure, respiratory quotient, or fasting body weight in the endotoxic rats. Administration of LPS was also associated with a decrease in the level of messenger RNA (mRNA) expression for LPL in white adipose tissue and skeletal muscle and an increase in the mRNA levels for uncoupling protein 3 in skeletal muscle. Bezafibrate treatment reversed the decline in LPL mRNA levels in white adipose tissue but not in the skeletal muscle tissue of the rats. The enhanced uncoupling protein 3 mRNA level in the endotoxic rats was not affected by bezafibrate treatment. Plasma concentration of leptin was increased by short-term LPS treatment. Bezafibrate decreased the level of plasma leptin significantly without affecting the level of leptin mRNA expression. These results suggest that bezafibrate may be an effective drug not only for impaired triacylglycerol metabolism, but also for anorexia in cachectic states induced by bacterial infections.


Transcription factors Csx/Nkx2.5 and GATA4 distinctly regulate expression of Ca2+ channels in neonatal rat heart.

The cardiac transcription factors Csx/Nkx2.5 and GATA4 play important roles in vertebrate heart development. Although mutations of Csx/Nkx2.5 or GATA4 are associated with various congenital heart diseases, their mechanism of action on cardiomyocyte function is not completely elucidated. In this study, we therefore investigated the actions of these transcription factors on the electrophysiological features and expression of ion channels in cardiomyocytes. Genes for transcription factors Csx/Nkx2.5 and GATA4 were transfected into rat neonatal cardiomyocytes by adenoviral infection. Action potentials, L-, T-type Ca(2+) channels and hyperpolarization-activated cation current (I(h)) of rat neonatal myocytes were recorded by patch clamp technique after adenoviral infection. Expression of ion channels was confirmed by real-time PCR. In Csx/Nkx2.5 overexpression myocytes, the spontaneous beating rate was markedly increased with an up-regulation of the Ca(v)3.2 T-type Ca(2+) channel, while in GATA4 overexpression myocytes, the T-type Ca(2+) channel was unchanged. On the other hand, the L-type Ca(2+) channel was down-regulated by both Csx/Nkx2.5 and GATA4 overexpression; the level of Ca(v)1.3 mRNA was dramatically decreased by Csx/Nkx2.5 overexpression. These results indicate that Csx/Nkx2.5 and GATA4 play important roles on the generation of pacemaker potentials modulating voltage-dependent Ca(2+) channels in the neonatal cardiomyocyte.

Journal of Molecular and Cellular Cardiology


Modulation of Pathogenicity with Norepinephrine Related to the Type III Secretion System of Vibrio parahaemolyticus.

Norepinephrine (NE) controls the functions of the gastrointestinal tract, but its role in the pathogenicity of enteropathogens is not clear. We examined the effect of NE on the pathogenicity of Vibrio parahaemolyticus with regard to its type III secretion systems (TTSSs). To evaluate the effect of NE on pathogenicity of V. parahaemolyticus, we examined the cytotoxic activity to Caco-2 cells and enterotoxicity by use of the rat ileal loop model. It has been reported that TTSS1 causes cytotoxicity and that TTSS2 causes enterotoxicity in the animal ileal loop model. Our results showed that, although NE alone did not affect the viability of Caco-2 cells, NE stimulated the cytotoxic activity of V. parahaemolyticus. Furthermore, NE increased the transcription of the TTSS1-related genes vscQ and vscU. These results indicate that NE regulates V. parahaemolyticus cytotoxic activity. The enterotoxicity of V. parahaemolyticus was increased by NE through interaction with alpha (1)-adrenergic receptors. These results indicate that alpha (1)-adrenergic receptors on the intestinal epithelium appear to interact with V. parahaemolyticus enterotoxicity. The present findings suggest that enteric NE may modulate V. parahaemolyticus pathogenicity.


Vitamin A deficiency induces a decrease in EEG delta power during sleep in mice

Recent report (Maret, S., Franken, P., Dauvilliers, Y., Ghyselinck, N.B., Chambon, P., Tafti, M., 2005. Retinoic acid signaling affects cortical synchrony during sleep. Science 310, 111-113.) has suggested that vitamin A (retinol and its derivatives) is genetically involved in the electroencephalogram (EEG) delta oscillation during sleep. However, this finding has not yet been confirmed by other studies. In this study, we attempted to record the sleep EEG and behavior, and to quantify striatal monoamines in mice fed a vitamin A-deficient (VAD) diet for 4 weeks, in order to clarify the linkage between the delta oscillation and vitamin A. VAD mice demonstrated a significant decrease in the delta power of the EEG. However, 6-h sleep deprivation caused the recovery of the delta power in VAD mice to a level similar to that of the control. VAD also caused the decrease of spontaneous activity throughout 24-h period. Furthermore, dihydroxyphenylacetic acid, a metabolite of dopamine, was decreased significantly in the striatal tissue of VAD mice. Our present results suggest that the deficiency of vitamin A causes the attenuation of delta power in NREM sleep and spontaneous activity. These attenuations may be related to the alteration of striatal dopaminergic function.


Visualization of cardiac dipole using a current density map: detection of cardiac current undetectable by electrocardiography using magnetocardiography.

A close relationship exists between electric current and the magnetic field. However, electricity and magnetism have different physical characteristics, and magnetocardiography (MCG) may provide information on cardiac current that is difficult to obtain by electrocardiography (ECG). In the present study, we investigated the issue of whether the current density map method, in which cardiac current is estimated from the magnetic gradient, facilitates the visualization of cardiac current undetectable by ECG. The subjects were 50 healthy adults (N group), 40 patients with left ventricular overloading (LVO group), 15 patients with right ventricular overloading (RVO group), 10 patients with an old inferior myocardial infarction (OMI group), and 30 patients with diabetes mellitus (DM group). MCGs were recorded with a second derivative superconducting quantum interference device (SQUID) gradiometer using liquid helium. Isopotential maps and current density maps from unipolar precordial ECG leads and MCGs, respectively, were prepared, and the cardiac electric current was examined. The current density map at the ventricular depolarization phase showed one peak of current density in the N group. However, in the OMI group, the current density map showed multiple peaks of current density areas. In the RVO group, two peaks of current densities were detected at the right superior region and left thoracic region and these two diploles appeared to be from the right and left ventricular derived cardiac currents, respectively. Moreover, there was a significant correlation between the magnitude of the current density from the right ventricle and the systolic pulmonary arterial pressure. The current density map at the ventricular repolarization phase in the N group showed only a single current source. However, abnormal current sources in the current density maps were frequently detected even in patients showing no abnormalities on isopotential maps in the LVO, DM, and OMI groups. The findings herein suggest that opposing dipoles of the ventricular depolarization and repolarization vectors were summed and evaluated as a single dipole in the electrocardiogram. However, MCG facilitated the detection of multiple dipoles because of its superior spatial resolution as well as difference in physical properties between magnetic and electrical fields. Our results suggest that MCG with a current density map is useful for detecting cardiac current undetectable by ECG in an early stage.

The Journal of Medical Investigation : JMI


BCAA-enriched snack improves nutritional state of cirrhosis

A late evening snack improves the catabolic state in patients with advanced liver cirrhosis. We tested whether long-term (3 mo) late evening snacking that included a branched-chain amino acid (BCAA)-enriched nutrient mixture produces a better nutritional state and better quality of life than ordinary food in patients with hepatitis C virus-positive liver cirrhosis. In a multicenter, randomized study, 48 patients with liver cirrhosis received late-evening supplementation with the BCAA-enriched nutrient mixture or ordinary food, such as a rice ball or bread, for 3 mo. During the study period, each patient was instructed on energy and protein intake. Blood biochemical data, nitrogen balance, respiratory quotient, and health-related quality of life (Short Form 36 questionnaire) were evaluated at baseline and at the end of the study. Total and late-evening energy intakes were similar in the two groups at 3 mo. Serum albumin level, nitrogen balance, and respiratory quotient were significantly improved by the BCAA mixture but not by ordinary food. The parameters of the Short Form 36 did not statistically significantly improve over 3 mo in either group. Long-term oral supplementation with a BCAA mixture is better than ordinary food in a late evening snack at improving the serum albumin level and the energy metabolism in patients with cirrhosis.


Angiotensin II inhibits insulin-induced actin stress fiber formation and glucose uptake via ERK1/2.

There is crosstalk in intracellular signaling between Angiotensin II (Ang II) and insulin. We hypothesized that the underlying mechanism might be related to changes in cytoskeleton. In the presence of 100 nM of Ang II, insulin-induced glucose uptake was decreased and insulin-induced actin filament organization was inhibited. PKC inhibitors, including GF109203x and p38MAPK inhibitor (SB203580) neither improved insulin-induced actin reorganization nor glucose uptake. In contrast, the Ang II-induced inhibition of glucose uptake and actin filament disorganization was reversed by 10 micromol ERK 1/2 MAPK inhibitor (PD98059). Pretreatment of Ang II increased ERK1/2 phosphorylation and inhibited insulin-induced Akt phosphorylation. The effect of Ang II on ERK1/2 phosphorylation was blocked by Ang II type 1 receptor antagonists, RNH6270 and PD98059 but not by SB203580 or Guanosine-5'-O-(2-ThioDiphosphate), a G-protein inhibitor. We next tested the effect of broad-spectrum matrix metalloproteinase (MMP) inhibitor (GM6001) on Ang II-inhibition of insulin signaling pathway. GM6001 did not improve Ang II-induced actin filament disorganization and did not inhibit ERK1/2 phosphorylation. From these data in L6 myotube, we conclude that Ang II negatively regulates the insulin signal not through MMP signaling pathway but specifically through MMP-independent ERK1/2 activation pathway, providing an alternative molecular mechanism for angiotensin-induced insulin resistance.


Evaluation of an infarction vector by magnetocardiogram: Detection of electromotive forces that cannot be deduced from an electrocardiogram.


APS-mediated Ubiquitination of the Insulin Receptor Enhances its Internalization but does not Induce its Degradation.

APS, a tyrosine kinase adaptor protein with pleckstrin homology and Src homology 2 domains, is rapidly and strongly tyrosine-phosphorylated by insulin receptor kinase upon insulin stimulation. We have previously shown that APS knockout mice have increased insulin sensitivity, and that this enhancement is possibly due to increased insulin-response on adipose tissues. However, the function of APS in insulin signaling has so far been controversial. Here, we report that APS enhanced ligand-dependent multi-ubiquitination of the insulin receptor (IR) in CHO cells overexpressing the IR. APS-mediated ubiquitination of the IR induced enhancement of the IR internalization, but did not affect the IR degradation. This finding shows one of the pleiotropic functions of APS in insulin signaling.


Molecular cloning of a murine glycerol-3-phosphate acyltransferase-like protein 1 (xGPAT1).

A novel murine glycerol-3-phosphate acyltransferase-like protein 1 (named xGPAT1) has been cloned. The mouse xGPAT1 gene is located on mouse Chromosome 2, spans >19 kb, and consists of at least 23 exons. The protein is 32% identical and 72% similar to mouse mitochondrial GPAT (mtGPAT) on the amino acid level. Sequencing analysis confirmed that xGPAT1 has a 2403-bp open reading frame (ORF) that encodes an 801-amino acid protein with an estimated molecular mass of 89.1 kDa. A hydropathy plot of the deduced xGPAT1 protein showed a high degree of similarity with that of the mtGPAT protein. Using 5'-rapid amplification of cDNA ends, two alternate, untranslated exon 1 (1a and b) isoforms were obtained, generating variants xGPAT1-v1 and xGPAT1-v2. xGPAT1-v1 is expressed in mouse heart, liver, spleen, kidney and murine inner medullary collecting duct 3 (mIMCD3) cells, while xGPAT1-v2 is expressed in mouse liver, spleen, kidney, white and brown adipose tissues and 3T3-L1 pre- and post-adipocytes. xGPAT1 was distributed in the membrane fraction and showed GPAT activity when epitope-tagged xGPAT1 was expressed in Chinese hamster ovary (CHO)-K1 cells.


NO-1886, a lipoprotein lipase activator, attenuates vascular smooth muscle contraction in rat aorta

The chemical compound [4-(4-bromo-2-cyano-phenylcarbamoyl)-benzyl]-phosphonic acid diethyl ester (NO-1886) is a lipoprotein lipase activator having beneficial effects on both diabetes control and the cardiovascular system. Preventing accumulation of lipids in the cell wall, in addition to improving insulin actions on vasculature, may indirectly contribute to the reducing effect of NO-1886 on vascular resistance. However, the direct effect of NO-1886 on vascular resistance, i.e., whether NO-1886 directly modulates the function of vascular endothelium and/or smooth muscle cells has not been investigated. In this study we therefore investigated the direct effect of NO-1886 on vascular contractility using rat aortic rings and cultured smooth muscle cell-line A10. The results show that administration of NO-1886 attenuated aortic contraction induced by phenylephrine and/or a high K(+) environment, in both the presence and absence of aortic endothelium. 1-(5-Chloronaphthalene-1-sulfonyl)homopiperazine hydrochloride (ML-9), a myosin light chain kinase (MLCK) inhibitor, blocked this inhibitory effect of NO-1886, whereas inhibitors of other signaling molecules such as calmodulin, protein kinase C and Rho-kinase had no effect. The vasorelaxant effect of NO-1886 was blocked in the absence of extracellular Ca(2+), or in the presence of the Ca(2+) channel inhibitor, verapamil. NO-1886 attenuated smooth muscle contraction induced by the cumulative addition of CaCl(2). In A10 cells, NO-1886 inhibited the membrane depolarization-induced initial peak of [Ca(2+)](i) in the presence of extracellular Ca(2+). This inhibition did not occur in the absence of extracellular Ca(2+). Taken together these results demonstrate that NO-1886 attenuates smooth muscle contraction and causes vasorelaxation by an extracellular Ca(2+)- and MLCK-dependent mechanism.


Haemolysin produced by Vibrio mimicus activates two Cl secretory pathways in cultured intestinal-like Caco-2 cells.

Haemolysin (VMH) is a virulent factor produced by Vibrio mimicus, a human pathogen that causes diarrhoea. As intestinal epithelial cells are the primary targets of haemolysin, we investigated its effects on ion transport in human colonic epithelial Caco-2 cells. VMH increased the cellular short circuit current (Isc), used to estimated ion fluxes, and 125I efflux of the cells. The VMH-induced increases in Isc and 125I efflux were suppressed by depleting Ca2+ from the medium or by pretreating the cells with BAPTA-AM or by Rp-adenosin 3',5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMPS). The Cl- channel inhibitors 4,4'-disothiocyanatostibene-2,2'-disulfonic acid (DIDS), glybenclamide, and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) suppressed the VMH-induced increases in Isc and 125I efflux. Moreover, VMH increased the intracellular concentrations of Ca2+ and cAMP. Thus, VMH stimulates Caco-2 cells to secrete Cl- by activating both Ca2+ -dependent and cAMP-dependent Cl- secretion mechanisms. VMH forms ion-permeable pores in the lipid bilayer that are non-selectively permeable to small ions. However, the ion permeability of these pores was not inhibited by glybenclamide and DIDS, and VMH did not change the cell membrane potential. These observations indicate that the pores formed on the cell membrane by VMH are unlikely to be involved in VMH-induced Cl- secretion. Notably, VMH stimulated fluid accumulation in the iliac loop test that was fully suppressed by a combination of DIDS and glybenclamide. Thus, Ca2+-dependent and cAMP-dependent Cl- secretion may be important therapeutic targets with regard to the diarrhoea that is induced by Vibrio mimicus.


Gastric motility and autonomic activity during obstructive sleep apnea.


Ginsenoside Re a main phytosterol of Panax ginseng activates cardiac potassium channels via a nongenomic pathway of sex hormones.

Ginseng root is one of the most popular herbs throughout the world and is believed to be a panacea and to promote longevity. It has been used as a medicine to protect against cardiac ischemia, a major cause of death in the West. We have previously demonstrated that ginsenoside Re, a main phytosterol of Panax ginseng, inhibits Ca(2+) accumulation in mitochondria during cardiac ischemia/reperfusion, which is attributable to nitric oxide (NO)-induced Ca(2+) channel inhibition and K(+) channel activation in cardiac myocytes. In this study, we provide compelling evidence that ginsenoside Re activates endothelial NO synthase (eNOS) to release NO, resulting in activation of the slowly activating delayed rectifier K(+) current. The eNOS activation occurs via a nongenomic pathway of each of androgen receptor, estrogen receptor-alpha, and progesterone receptor, in which c-Src, phosphoinositide 3-kinase, Akt, and eNOS are sequentially activated. However, ginsenoside Re does not stimulate proliferation of androgen-responsive LNCaP cells and estrogen-responsive MCF-7 cells, implying that ginsenoside Re does not activate a genomic pathway of sex hormone receptors. Fluorescence resonance energy transfer experiments with a probe, SCCoR (single cell coactivator recruitment), indicate that the lack of genomic action is attributable to failure of coactivator recruitment. Thus, ginsenoside Re acts as a specific agonist for the nongenomic pathway of sex steroid receptors, and NO released from activated eNOS underlies cardiac K(+) channel activation and protection against ischemia-reperfusion injury.


Angiotensin II activates intermediate-conductance Ca2+-activated K+ channels in arterial smooth muscle cells.

Angiostensin II (Ang II) regulates the migration and proliferation of vascular smooth muscle cells. Recent studies indicate that intermediate-conductance Ca2+ -activated K+ (IKca) channels have an important role in cell migration and proliferation. It is not known, however, whether the action of Ang II is linked to IKca channel regulation. Here, we investigated the modulation of IKca channels by Ang II in artery smooth muscle cells. Functional IKca channel expression in cultured embryonic rat aorta smooth muscle (A10) cells was studied using the patch-clamp technique. These cells predominantly express IKca channels. In contrast, large-conductance Ca2+ -activated K+ (BKca) currents were rarely observed in excised patches. Ang II increased the IKca current in a contration-dependent manner. Losartan (1.0 microM), an AT1 selective antagonist, abolished the activation of IKca channels by Ang II. Pretreatment with 100 microM myristoylated protein kinase C inhibitor peptide 20-28 or 10 microM GF109203X completely abolished the AngII-induced activation of IKca currents, whereas the action of Ang II was not prevented in the presence of 100 microM Rp-cyclic 3', 5'-hydrogen phosphotiate adenosine triethylammonium, a protein kinase A inhibitor, or 1.0 microM KT-5823, a protein kinase G inhibitor. A membrane permeant analogue of diacylglycerol 1, 2-dioctanoyl-sn-glycerol (10 microM) induced the activation of IKca currents. These data suggest that Ang II activates IKca channels through the activation of protein kinase C, and the AT1 receptor is involved in the regulation of these channels.

Journal of Molecular and Cellular Cardiology


Effect of TRB3 on Insulin and Nutrient-stimulated Hepatic p70 S6 Kinase Activity

Insulin and nutrients activate hepatic p70 S6 kinase (S6K1) to regulate protein synthesis. Paradoxically, activation of S6K1 also leads to the development of insulin resistance. In this study, we investigated the effect of TRB3, which acts as an endogenous inhibitor of Akt, on S6K1 activity in vitro and in vivo. In cultured cells, overexpression of TRB3 completely inhibited insulin-stimulated S6K1 activation by mammalian target of rapamycin, whereas knockdown of endogenous TRB3 increased both basal and insulin-stimulated activity. In C57BL/6 mice, adenoviral overexpression of TRB3 inhibited insulin-stimulated activation of hepatic S6K1. In contrast, overexpression of TRB3 did not inhibit nutrient-stimulated S6K1 activity. We also investigated the effect of starvation, feeding, or insulin treatment on TRB3 levels and S6K1 activity in the liver of C57BL/6 and db/db mice. Both insulin and feeding activate S6K1 in db/db mice, but only insulin activates in the C57BL/6 strain. TRB3 levels were 3.5-fold higher in db/db mice than C57BL/6 mice and were unresponsive to feeding or insulin, whereas both treatments reduced TRB3 in C57BL/6 mice. Akt was activated by insulin alone in the C57BL/6 strain and but not in db/db mice. Both insulin and feeding activated mammalian target of rapamycin similarly in these mice; however, feeding was unable to activate the downstream target S6K1 in C57BL/6 mice. These results suggest that the nutrient excess in the hyperphagic, hyperinsulinemic db/db mouse primes the hepatocyte to respond to nutrients resulting in elevated S6K1 activity. The combination of elevated TRB3 and constitutive S6K1 activity results in decreased insulin signaling via the IRS-1/phosphatidylinositol 3-kinase/Akt pathway.


Risk factors associated with soft coronary artery plaques in Japanese as determined by 16 slice multidetector-row computed tomography.

The acute coronary syndrome is often caused by the rupture of plaques and thrombus formation even without significant stenosis, and patients with soft plaques, but without significant stenosis evidenced by coronary angiography (CAG), often develop an acute coronary syndrome. To address this discrepancy, a qualitative diagnosis of coronary plaques using a 16 slice multidetector-row CT was conducted. Volume rendering and cross-sectional MPR images were obtained. Based on the CT values, plaques on the coronary artery wall were classified as lipid-rich soft plaques (CT value<50 HU) and non-soft plaques (>50 HU).A significant correlation was observed between the percent stenosis determined in cross-sectional MPR images and those determined by CAG (r=+0.92, p<0.01). Diffuse plaques with CT values of less than 50 HU often caused stenosis at level of 75% or less, which were not indicated by percutaneous transluminal coronary angioplasty. Although diffuse soft plaques with CT values less than 50 HU are not an indication of intervention, a risk of an acute coronary syndrome exists, due to rupture. These soft plaques must be stabilized by treatment even when they do not cause significant stenosis, and MDCT is considered to be useful for their evaluation.

The Journal of Medical Investigation : JMI


Nateglinide with glibenclamide examination using the respiratory quotient (RQ).

The respiratory quotient (RQ) is useful for evaluating glucose and lipid metabolism in vivo. We previously reported that the RQ value, even after fasting, was high in diabetics being treated with sulphonylurea (SU), which might explain the accumulation of fat, leading to weight gain in such individuals. In the present study, we measured the RQ in type II diabetic patients who were being treated with a rapid-onset/short-duration insulinotropic agent, nateglinide, and compared it with those being treated with SU. A glucose tolerance test was performed in 20 patients with type II diabetes mellitus treated with nateglinide and in 14 patients treated with SU, and the RQ was simultaneously measured. The RQ values in the patients treated with nateglinide, were similar to those in healthy adults, but was lower than in those treated with SU. No weight gain was observed in patients treated with nateglinide. A significant weight gain was reported in subjects treated with SU, accompanied by an increase in RQ. However, weight gain was less frequent in diabetics treated with nateglinide.


Antidepressant effect of extracts from Ginkgo biloba leaves in behavioral models

Extracts of Ginkgo biloba (EGB) are a complex product prepared from green leaves of the Ginkgo biloba tree. In the present study, the antidepressant effect of EGB was examined using two behavioral models, the forced swimming test (FST) in rats and tail suspension test (TST) in mice. EGB significantly reduced immobility time in the FST at a dosage of 10 and 50 mg/kg body weight after repeated oral treatment for 14 d, although no change of motor dysfunction was observed with the same dosage in the open field test. These results indicate that EGB might possess an antidepressant activity. In addition, EGB markedly shortened immobility time in the TST after acute inter-peritoneal treatment at a dosage of 50 and 100 mg/kg body weight. The present study clearly demonstrated that EGB exerts an antidepressant effect in these two behavioral models.


Pore formation of thermostable direct hemolysin secreted from Vibrio parahaemolyticus in lipid bilayers.

Vibrio parahaemolyticus secretes thermostable direct hemolysin (TDH), a major virulence factor. Earlier studies report that TDH is a pore-forming toxin. However, the characteristics of pores formed by TDH in the lipid bilayer, which is permeable to small ions, remain to be elucidated. Ion channel-like activities were observed in lipid bilayers containing TDH. Three types of conductance were identified. All the channels displayed relatively low ion selectivity, and similar ion permeability. The Cl- channel inhibitors, DIDS, glybenclamide, and NPPB, did not affect the channel activity of pores formed by TDH. R7, a mutant toxin of TDH, also forms pores with channel-like activity in lipid bilayers. The ion permeability of these channels is similar to that of TDH. R7 binds cultured cells and liposomes to a lower extent, compared to TDH. R7 does not display significant hemolytic activity and cell cytotoxicity, possibly owing to the difficulty of insertion into lipid membranes. Once R7 is assembled within lipid membranes, it may assume the same structure as TDH. The authors propose that the single glycine at position 62, substituted with serine in the R7 mutant toxin, plays an important role in TDH insertion into the lipid bilayer.


Exposure to music in the perinatal period enhances learning performance and alters BDNF/TrkB signaling in mice as adults.

Music has been suggested to have a beneficial effect on various types of performance in humans. However, the physiological and molecular mechanism of this effect remains unclear. We examined the effect of music exposure during the perinatal period on learning behavior in adult mice, and measured the levels of brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine kinase receptor B (TrkB), which play critical roles in synaptic plasticity. In addition, we measured the levels of 3-phosphoinositide-dependent protein kinase-1 (PDK1) and mitogen-activated protein kinase (MAPK), downstream targets of two main pathways in BDNF/TrkB signaling. Music-exposed mice completed a maze learning task with fewer errors than the white noise-exposed mice and had lower levels of BDNF and higher levels of TrkB and PDK1 in the cortex. MAPK levels were unchanged. Furthermore, TrkB and PDK1 protein levels in the cortex showed a significant negative correlation with the number of errors on the maze. These results suggest that perinatal exposure of mice to music has an influence on BDNF/TrkB signaling and its intracellular signaling pathway targets, including PDK1, and thus may induce improved learning and memory functions.


Aeromonas sobria hemolysin causes diarrhea by increasing secretion of HCO3-

Aeromonas sobria hemolysin (ASH) is one of the major virulence factors produced by A. sobria, a causative agent of diarrhea in humans. We investigated the effects of ASH on anion transport in human colonic epithelial cells. ASH increased short circuit currents across the intestinal epithelia, which were suppressed by anion channel antagonists, such as carbonic anhydrase inhibitors, and by the removal of external HCO3-. Iliac fluid accumulation was also inhibited by carbonic anhydrase inhibitors. The results suggest that ASH activates HCO3- secretion, whose level correlates with the severity of diarrhea.


Relationships between thermic effect of food insulin resistance and autonomic nervous activity.

The thermic effect of food (TEF) is higher in lean than in obese human subjects. Relationships between TEF and insulin resistance during meals, from the point of view of autonomic nervous activity, were evaluated. Autonomic nervous activity was evaluated in 20 young adults using the spectral analysis of heart rate variability from one hour before to two hours after a meal. Heart rate data were analyzed based on low frequency components (LF power, 0.04-0.15 Hz), high frequency components (HF power, 0.15-0.40 Hz), and LF/HF ratios. Energy expenditure and the TEF were measured 30 min after a meal. Homeostasis model of insulin resistance index (HOMA-IR) was also measured. The LF/HF ratio was significantly increased 30 min after a meal (p<0.05). No correlation between LF power and HF power with TEF was found, but the LF/HF ratio was significantly and positively correlated with TEF (r=+0.56, p<0.05). Moreover, a significant negative correlation was found between the HOMA-IR and TEF (r=-0.601, p<0.05). The findings suggest that a reduction in insulin sensitivity induces a poor response of sympathetic nervous activity in the postprandial phase and a reduction in postprandial energy expenditure.


Effects of thrombus suction therapy on myocardial blood flow disorders in males with acute inferior myocardial infarction.

Several studies have reported that the use of a distal protection device decreases the incidence of slow-flow and/or no-reflow in patients with myocardial infarctions. In the present study, we investigated the influence of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter on coronary microcirculation disorders in patients with acute myocardial infarction using the natriuretic polypeptide (ANP), the brain natriuretic peptide (BNP), and (99m)Tc-tetrofosmin myocardial scintigraphy (TF). The group consisted of a 77 patients with initial inferior myocardial infarction who had undergone emergency coronary angioplasty. The patients were randomly divided into: Group D (n=28), in which a direct stent alone was inserted, Group R/T (n=25), in which a stent was inserted after RESCUE system or a Thrombuster system was performed, and Group P (n=24), in which a stent was inserted after thrombus suction using a PercuSurge GuardWire catheter. Patients with coronary slow-flow/no-reflow were 3, 2 and 0 cases in Group D, Group R / T and Group P, respectively. In the present study, patients with good-reflow were enrolled in order to investigate the coronary microcirculation disorder in patients with visually similar coronary blood flow obtained in coronary angiography after percutaneous coronary reperfusion therapy. TF myocardial scintigraphy was performed 10+/-3 days after admission. Bull's eye images were divided into 8 sections, and each section was evaluated in 4 grades. The grade of each segment was regarded as the defect score. The results were compared with the database prepared based on bull's eye maps from 50 healthy adults in our hospital, and count areas of -2 x SD (standard deviation) or less were calculated as the extent score (%), reflecting the area in which myocardial blood flow was decreased. The extent and severity scores in Groups P and R/T were significantly lower than those in Group D. Coronary angiography at the chronic stage (6 months after surgery) showed the patency of the responsible vascular lesion in all patients. However, the ANP, BNP, cardiac index, and pulmonary capillary wedge pressure (PCWP) were significantly improved in Groups R/T and P, compared to Group D (p<0.01). These results suggest that the use of a RESCUE/Thrombuster system and a PercuSurge GuardWire catheter system in patients with acute inferior wall infarction improves coronary microcirculation disorders and acute- to chronic-phase cardiac function.


Efficacy of glimepiride on insulin resistance adipocytokines and atherosclerosis.

Plasma adiponectin levels increase after the administration of glimepiride. This unique effects would also be expected to improve other adipocytokines and have anti-atherosclerotic action in patients with metabolic syndrome. Thirty-four patients with type 2 diabetes mellitus who were administrated glibenclamide were randomly divided into two groups. In 20 patients glibenclamide was changed to glimepiride (GP group), and the administration of glibenclamide (GB group) was continued in 14 patients. Twelve patients receiving insulin therapy (INS group) were enrolled for comparison. The levels of plasma adiponectin, high sensitive-CRP, TNF-alpha, interleukin-6, homeostasis model assessment-insulin resistance (HOMA-IR), brachial-ankle pulse wave velocity (baPWV) and augmentation index (AI) were measured before and 28 weeks after the therapy. HOMA-IR in the GP group was significantly decreased compared to the GB group. Plasma adiponectin levels were significantly increased in the GP group but not in the other groups. TNF-alpha, interleukin-6 and high sensitive-CRP levels were significantly decreased in the GP group, but not in the other groups. The baPWV and AI levels did not change in either the GB or the INS group, but were significantly decreased in the GP group. Glimepiride appears to improve insulin resistance and atherosclerotic disorders.

The Journal of Medical Investigation : JMI


(123)I-metaiodo-benzylguanidine myocardial scintigraphy in the Brugada-type ECG.

The degree of ST-segment elevation and amplitude of J waves, which may change in patients with the Brugada-type electrocardiogram (ECG) over time, are influenced by autonomic nervous activity and the administration of antiarrhythmic drugs. In the present study, we evaluated whether the shape of ST-segment elevation in patients with a Brugada-type ECG might alter the parameters of an 123I-MIBG myocardial scintigraphy and body surface signal-averaged ECG (SAECG). The subjects consisted of 12 patients with a Brugada-type ECG and 15 healthy volunteers (N group). The patients with a Brugada-type ECG were classified into the following 2 groups based on the type of ST-segment elevation: 6 patients with the coved type ST-segment elevation (C group), and 6 patients with the saddle-back type ST-segment elevation (S group). Planar and SPECT images were obtained 15 minutes (early images) and 3 hours (delayed images) after the administration of 123I-MIBG, respectively. In addition, the washout rate (% WR) of 123I-MIBG was obtained in a bull's eye map of the SPECT image. There were no significant differences in the early H/M ratio between the C and S groups. In the C group, however, there were some patients who showed a decreased accumulation or defect of 123I-MIBG in the planar and SPECT images. Furthermore, in contrast to the N and S groups, the C group showed a decreased delayed H/M ratio and increased % WR. SAECG did not show any significant differences between the S and C groups. These results of the present study suggest that the shape of ST-segment elevation may be associated with myocardial autonomic nervous function. In addition, the electric heterogeneity of the action potential in the right ventricular epicardial myocardium, which is frequently influenced by autonomic nervous activity, is closely associated with the development of Brugada syndrome.


Evalution of episodes of sleep apnea in patients with liver cirrhosis

Obstructive sleep apnea syndrome (OSAS) has been reported to be a new complication of liver cirrhosis with ascites. This fact prompted a study of episodes of sleep apnea as a function of the severity of cirrhosis. Forty eight patients with type C liver cirrhosis were divided according to the Child-Pugh score into 3 groups: Group A (16 patients with grade A cirrhosis), Group B (16 patients with grade B cirrhosis), and Group C (16 patients with grade C cirrhosis). Portable sleep polygraphs (Fuji RC, Inc. Tokyo, Japan) were attached to the subjects, and oronasal respiration, tracheal sounds, respiratory movements of the chest, and percutaneous arterial oxygen saturation continuously were recorded. A decrease in the mean airflow to 50% or less was defined as hypopnea, and the number per hour of episodes of apnea and hypopnea per hour lasting 10 seconds or longer (AHI) was counted. A Holter ECG was also recorded, and spectral heart rate variability during sleep was analyzed by measuring low frequency power (0.04-0.15 Hz, LF power), high frequency power (0.15-0.40 Hz, HF power), the ratio of LF power to HF power (LF/HF ratio), and very low frequency power (0.008-0.04 Hz, VLF power). The difference in QT interval between the lead CM5 and the lead CM1 (QTc dispersion) was also examined. AHI was significantly higher in Group C than in Groups A and B (p<0.05). In Group C, 6 patients with 20 times or more AHI per hour, obstructive sleep apnea, in which respiratory chest movements occur but oronasal respiration decreases or disappears, was observed. Spectral analyses of heart rate variability showed a decrease in HF power without sleep apnea, but increases in HF power and VLF power were observed during sleep apnea. The QTc dispersion increased during episodes of sleep apnea. As the stage of liver cirrhosis advanced, sleep apnea appeared, and changes in autonomic nervous activities were observed. Furthermore, QTc dispersion was increased during episodes of sleep apnea, presumably increasing the risk of ventricular arrhythmia.


Relationship between adhesion molecules with hs-CRP and changes therein after ARB (Valsartan) administration in patients with obstructive sleep apnea syndrome

It has been reported that a relationship exists between obstructive sleep apnea syndrome (OSAS) and cardiovascular and cerebrovascular diseases. To address this issue, we evaluated whether OSAS is associated with adhesion molecules and inflammatory signs, important indicators of atherosclerosis. Levels of high-sensitivity CRP (hs-CRP) and intercellular adhesion molecule-1 (ICAM-1) were measured in 30 patients with ischemic heart disease, confirmed by coronary arteriography (IHD group). Twenty healthy volunteers without sleep apnea were used as controls (Group N). Sleeping respiratory information was collected using a portable sleep polygraph, together on information about oronasal flow, tracheal sound, chest respiration, and percutaneous oxygen saturation (SpO2) to obtain the apnea-hypopnea index (AHI). In the IHD group, 9 (30%) of the 30 patients showed evidence of OSAS [IHD(AHI> or = 40) group] and 21 did not [IHD(AHI<40) group]. The levels of hs-CRP and ICAM-1 were significantly higher in the IHD group than in the N group (p<0.01). Moreover, the levels of hs-CRP and ICAM-1 were significantly higher in the IHD(AHI > or = 40) group than in the IHD(AHI<40) group (p<0.01). However, after the administration of valsartan, angiotensin II receptor antagonists (ARB) to both IHD groups, the levels of hs-CRP and ICAM-1 decreased significantly in both groups. Moreover, a multivariate analysis revealed that the levels of hs-CRP and ICAM-1 were associated with the severity of sleep apnea. These findings suggest that, in OSAS the levels of hs-CRP and ICAM-1 are decreased and that the administration of ARB decreases the risk of atherosclerosis.


Human airway trypsin-like protease stimulates human bronchial fibroblast proliferation in a protease-activated receptor-2-dependent pathway.

Human airway trypsin-like protease (HAT) was isolated from airway secretions and localized to bronchial epithelial cells by immunohistochemistry. In the present study, we examined whether HAT could stimulate DNA synthesis and proliferation of primary human bronchial fibroblasts (HBF). HAT significantly stimulated the proliferation of HBF by 20-55%, a level similar to that of the mitogenic activity of lung mast cell tryptase (MCT). HAT also stimulated the incorporation of [3H]thymidine in HBF, and this HAT-induced DNA synthesis was abolished by leupeptin. Protease-activated receptor-2 (PAR-2) mRNA was expressed and localized to the cell surface in HBF. PAR-2 activating peptide (AP) also enhanced DNA synthesis, and both HAT and PAR-2 AP induced receptor internalization, similar to the response to trypsin. Pretreatment of HBF with anti-PAR-2 antibody significantly suppressed both HAT and PAR-2 AP-induced DNA synthesis. In addition, HAT and PAR-2 AP induced intracellular Ca2+ mobilization in HBF. The HAT-induced increase in Ca2+ was desensitized by pretreatment with trypsin or PAR-2 AP. U0126, a specific MAPK inhibitor, completely inhibited HAT-induced DNA synthesis as well as HAT-induced phosphorylation of MAPK. The effect of HAT and MCT together was additive, whereas the effect of HAT and insulin together on HBF DNA synthesis was synergistic. These results indicate that HAT stimulates fibroblast proliferation in bronchial airways through a PAR-2-dependent MEK-MAPK mediated pathway and that HAT is linked to airway processes involving fibroblasts.

American Journal of Physiology. Lung Cellular and Molecular Physiology


Monoamine Oxidase A Activity and Norepinephrine Level in Hippocampus Determine Hyperwheel Running in SPORTS Rats.

An understanding of neurological mechanisms for wheel running by rodents, especially with high exercise activity, would be applicable to a strategy for promotion of exercise motivation in humans. One of several brain regions that are candidates for the regulation of physical exercise is the hippocampus. Here we examined the running activity of Spontaneously-Running-Tokushima-Shikoku (SPORTS) rat, a new animal model for high levels of wheel-running activity, and its relation with the hippocampal norepinephrine (NE) system including the levels of NE, adrenergic receptors, and degradation enzymes for monoamines. In the hippocampus of SPORTS rats, the level of NE in extracellular fluid was augmented, whereas the level in the homogenate of the whole tissue was decreased even for sedentary conditions. Elevated extracellular NE caused downregulation of alpha(2)-adrenergic receptors in the hippocampus of SPORTS rats. Local administration of alpha(2)-adrenergic receptor antagonist yohimbine, but not of alpha(2)-agonist clonidine, into the hippocampus suppressed high running activity in SPORTS rats. The protein expression and the activity levels of monoamine oxidase A (MAOA), a critical enzyme for the degradation of NE, were decreased in the hippocampus of SPORTS rats to increase extracellular NE level. Thus, inhibition of oxidase activity in normal Wistar rats markedly increased wheel-running activity. These results indicate that decreased MAOA activity, elevation of extracellular NE, and alpha(2)-adrenergic receptors in the hippocampus determine the neural basis of the psychological regulation of exercise behavior in SPORTS rats.


Sarpogrelate hydrochloride an antagonist of 5-hydroxytryptamine receptor improves skin flap survival and suppresses thrombus formation in injured microvessels of rabbits.

The authors carried out two studies to examine the effects of the 5-hydroxytryptamine receptor antagonist, sarpogrelate hydrochloride (SH), on flap necrosis. The first study measured survival rates and included histologic examination of random-pattern skin flaps in rabbits. The second study assessed the time to complete obstruction of blood flow with the artificial thrombus formation method, and the time for leukocytes to adhere to the endothelium of microvessels in a rabbit-ear chamber. The treatment groups were injected with SH. The survival rates of skin flaps in the SH-treated group were increased significantly. Histologic examination of vessels in the control group revealed that vessels in the deep dermis were obstructed completely by thrombi, whereas such vessels were not obstructed in the SH-treated group. Thrombus formation time and leukocyte adhesion time in the SH-treated group were prolonged and decreased, respectively. Thus, SH maintained flap circulation and promoted flap survival by preventing thrombus formation.


Effects of forced swimming stress on rat brain function

Chronic stress has been reported to be an essential factor for depression. In this study, the effect of forced swimming stress on neurotransmitters and cellular signaling pathway contributing to brain functions was investigated using the forced swimming test (FST) in order to understanding of mechanisms to regulate stress signals in brain. Antidepressant drug, imipramine, significantly reduced the immobility time of male rats in the FST by 85% at a dose of 15 mg/kg for 2 weeks. This result indicated that the swimming stress caused a depressed state in the rats without administration of imipramine. Swimming stress significantly lowered the serotonergic ratio and also markedly enhanced the phosphorylation of ERK1/2 in the hypothalamus region compared to the rats without FST. These phenomena may be included in key mechanisms of the development of depression.


高運動モデルラットSPORTSの海馬におけるノルエピネフリン動態と自発運動量

高運動モデルラットSPORTSの海馬におけるノルエピネフリン動態と自発運動量


抗不整脈薬の作用機序と心電図変化

抗不整脈薬の作用機序と心電図変化


Approach to novel functional foods for stress control 2. Microarray assessment of exercise in healthy volunteers.

DNA microarray was used to measure stress response by exercise in peripheral blood leukocytes. Aerobic exercise did not alter mRNA pattern or urinary secretion of 8-hydroxy-2'-deoxyguanosine (8-OHdG). Strenuous exercise increased urinary secretion of 8-OHdG and altered mRNA pattern in microarray. These results suggest that moderate exercise, i. e. aerobic exercise, did not show any change in 8-OHdG, an oxidative stress marker, or mRNA expression in the leukocytes, which might reflect whole body neurohormanal changes. In addition, strenuous exercise produced quite different expression pattern from those of psychological stress.

The Journal of Medical Investigation : JMI


Approach to novel functional foods for stress control 3. Establishment of stress-resistant rat model and its mechanism.

A stress-resistant rat model was introduced. SPORTS (Spontaneously-Running-Tokushima-Shikoku) rats showed significantly shorter time of immobility in the forced swim test compared to control Wister rats. Increase norepinephrine concentration secondary to decreased activity of monoamine oxidase A (MAOA) in hippocampus was observed in this model rats. This model rats are considered to be useful for studying the mechanism of psychological stress.


The relationship between autonomic nervous activity and physical activity in children

There have been few studies that have reported on heart rate variability and the development of autonomic nervous function in children. This study investigated the relationship between heart rate variabilities at night and physical activity in children. The study subjects were 29 children, including 17 boys and 12 girls. The daily activity product and heart rate variabilities during sleep at night (00.00-05.00 hours) were measured and several aspects of these parameters were analyzed. In one child (an 8-year-old girl), heart rate variability and the physical activity product were measured for 12 days. There was a negative correlation between the mean R-R interval and the duration (min) of heavy exercise per day (r = -0.39, P < 0.05). In the 8-year-old girl, from whom data was obtained for 12 days, the duration of heavy exercise per day was negatively correlated with the mean R-R interval (r = -0.63, P < 0.05), the number of changes in successive R-R intervals greater than 50 msec (RR50) (r = -0.74, P < 0.01), and the high frequency (HF) component (r = -0.66, P < 0.05). Furthermore, the daily number of steps was negatively correlated with the mean R-R interval (r = -0.66, P < 0.05), RR50 (r = -0.71, P < 0.05) and the HF component (r = -0.66, P < 0.05). There was a negative correlation between the amounts of energy consumption and the mean R-R interval (r = -0.69, P < 0.05). There was a negative correlation between the amounts of energy consumption and RR50 (r = -0.76, P < 0.01). Moreover, there was also a negative correlation between the amount of energy consumption and the HF component (r = -0.71, P < 0.05). These findings suggested that physical activities increase heart rate during sleep, but reduce parasympathetic nervous activity at night. Because both the HF component and RR50 reduce with growth, the exercise-related inhibition of parasympathetic nervous activity may be a developmental stimulus to reach a balanced autonomic nervous pattern in adults.


The Journal of Japan Biomagnetism and Bioelectromagnetics Society


Evaluation of gastric emptying by electrogastrography and ultrasonography in gastroesophageal reflux disease


A pore-forming toxin produced by Aeromonas sobria activates Ca2+ dependent Cl- secretion.

Bacteria produce many types of hemolysin that induce diarrhea by mechanisms that are not completely understood. Aeromonas sobria hemolysin (ASH) is a major virulence factor produced by A. sobria, a human pathogen that causes diarrhea. Since epithelial cells in the intestine are the primary targets of hemolysin, we investigated the effects of ASH on ion transport in human colonic epithelial (Caco-2) cells. ASH increased short-circuit currents (Isc) in a dose-dependent manner, and it also activated a 125I efflux from Caco-2 cells. ASH-induced Isc increases and 125I efflux activations were both suppressed by low Ca2+ levels in the extracellular solution or by pretreatment with the Ca2+ chlelator BAPTA-AM. Intracellular Ca2+ levels were increased by ASH in a biphasic fashion characterized by a rapid sharp increase (peak 1) followed by a sustained low plateau (peak 2). ASH-induced peak 1 was inhibited by pretreatment with pertussis toxin, indicating that Ca2+ was mobilized from intracellular stores, and peak 2 was induced by an influx of extracellular Ca2+. Peak 2 but not peak 1 was related to Cl- secretion. These results indicate that ASH activates Ca2+-dependent Cl- secretion.


Transforming growth factor β stimulates rheumatoid synovial fibroblasts via the type receptor

Transforming growth factor (TGF)-beta regulates the function of fibroblasts, and has been shown to have a role in the pathogenesis of rheumatoid arthritis (RA) because several studies have demonstrated the presence of TGF-beta in the synovial tissue and synovial fluids of RA patients. In this study, we examined the expression of TGF-beta receptors in synovial fibroblasts of patients with RA and demonstrated the significance in functional responses of synovial fibroblasts to TGF-beta in this disorder. Transforming growth factor beta1 stimulated the expression of connective tissue growth factor (CTGF) in fibroblasts of patients with RA more than in those of patients with osteoarthritis (OA). Transforming growth factor beta1 induced the chemotactic migration of RA synovial fibroblasts and inhibited their proliferation significantly more than OA synovial fibroblasts. Both RA and OA synovial fibroblasts expressed detectable amounts of TGF-beta receptor type II mRNA, but the expression was higher in RA patients than in OA patients, as assessed by reverse transcriptase-polymerase chain reaction. There was no significant difference in the expression of TGF-beta receptor type I or type III in synovial fibroblasts between RA and OA patients. These results indicate that synovial fibroblasts of RA patients express the increased TGF-beta receptor type II, which is associated with altered responses to TGF-beta observed in CTGF expression, chemotaxis, and proliferation of RA synovial fibroblasts, and may have an important role in the pathogenesis of RA.


Association of Inflammatory Marker and Highly Sensitive C-Reactive Protein With Aerobic Exercise Capacity, Maximum Oxygen Uptake and Insulin Resistance in Healthy Middle-Aged Volunteers

Increased levels of inflammation markers, such as C-reactive protein (CRP) and tumor necrosis factor-alpha , have been found in insulin resistance syndrome. Those with elevated levels of high-sensitive CRP (hs-CRP) are at a higher risk for coronary heart disease. In the present study, we evaluated whether maximum oxygen uptake and insulin resistance are related to hs-CRP for the primary prevention of coronary heart disease. The subjects were 50 subjects who did not have diabetes mellitus. A multi-step treadmill exercise test was performed to obtain the maximum oxygen uptake when assessed by computerized breath-by-breath analysis. As an index of insulin resistance, the homeostasis model insulin resistance index (HOMA-R; fasting glucose x fasting insulin/405) was used. In addition, bodyweight, body mass index, subcutaneous fat thickness, total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride were measured. Multivariate analysis revealed that hs-CRP was significantly correlated with HDL-cholesterol, uric acid, gamma-glutamyl transpeptidase and maximum oxygen uptake. The maximum oxygen uptake showed the smallest odds ratio was in terms of the relationship with hs-CRP. The present study suggests that the development of exercising habits increases the maximum oxygen uptake. Furthermore, an elevated maximum oxygen uptake decreases HOMA-R and reduces the inflammatory marker CRP, suggesting that exercising habit plays an important role in the primary prevention of coronary heart disease.


Cloning and establishment of a line of rats for high levels of voluntary running

We generated an original Wistar line of rats that displayed increased levels of wheel running, which we named SPORTS (Spontaneously-Running-Tokushima-Shikoku). Male SPORTS rats ran voluntarily in a running wheel almost six times longer than male control Wistar rats, established without selection for their running activity. The running phenotype of female SPORTS rats was the same as female control Wistar rats. However, male offspring from the cross-mating between a female SPORTS rat and a male control rat also showed a similar level of hyper-running activity as the original SPORTS line. Compared to control rats, male SPORTS rats had lower levels of mean body weight, abdominal fat and plasma insulin after 4 weeks of running. It is likely that all these beneficial changes observed in the SPORTS rats reflected the increases in glucose disposal we observed in oral glucose tolerance tests carried out on the animals. We also found hyper-running caused a significant increase in skeletal muscle oxidative capacity, measured as the ratio of malate dehydrogenase to phosphofructokinase activity, an index of aerobic metabolism. These results indicate that the SPORTS rat may be a good animal model for determining the mechanisms responsible for up-regulation of running motivation, in addition to investigating changes in nutrient metabolism induced by high intensity exercise.


A pore-forming toxin produced by Aeromonas sobria activates cAMP-dependent Cl- secretory pathways to cause diarrhea

Aeromonas sobria hemolysin (ASH) is one of the major virulence factors produced by A. sobria, a human pathogen that causes diarrhea. We investigated the effects of ASH on Cl(-) transport in human colonic epithelial cells. ASH increased short-circuit currents (Isc) and (125)I efflux from Caco-2 cells, indicating ASH activate Cl(-) secretion. Additions of inhibitors of cyclic AMP dependent Cl(-) channels, glybenclamide and NPPB suppressed the Isc and (125)I efflux increases induced by ASH. And ASH increased the intracellular cyclic AMP concentration. Moreover, ASH stimulated fluid accumulation in the iliac loop test, and glybenclamide and NPPB suppressed this fluid accumulation. Thus, cAMP-dependent Cl(-) secretory pathway could be related with diarrhea induced by A. sobria.


Relationship between pulse wave velocity and circulatory hemodynamics during upper gastrointestinal endoscopy


Molecular mechanisms underlying ketamine-mediated inhibition of sarcolemmal adenosine triphosphate-sensitive potassium channels.

Ketamine inhibits adenosine triphosphate-sensitive potassium (KATP) channels, which results in the blocking of ischemic preconditioning in the heart and inhibition of vasorelaxation induced by KATP channel openers. In the current study, the authors investigated the molecular mechanisms of ketamine's actions on sarcolemmal KATP channels that are reassociated by expressed subunits, inwardly rectifying potassium channels (Kir6.1 or Kir6.2) and sulfonylurea receptors (SUR1, SUR2A, or SUR2B). The authors used inside-out patch clamp configurations to investigate the effects of ketamine on the activities of reassociated Kir6.0/SUR channels containing wild-type, mutant, or chimeric SURs expressed in COS-7 cells. Ketamine racemate inhibited the activities of the reassociated KATP channels in a SUR subtype-dependent manner: SUR2A/Kir6.2 (IC50 = 83 microM), SUR2B/Kir6.1 (IC50 = 77 microM), SUR2B/Kir6.2 (IC50 = 89 microM), and SUR1/Kir6.2 (IC50 = 1487 microM). S-(+)-ketamine was significantly less potent than ketamine racemate in blocking all types of reassociated KATP channels. The ketamine racemate and S-(+)-ketamine both inhibited channel currents of the truncated isoform of Kir6.2 (Kir6.2DeltaC36) with very low affinity. Application of 100 mum magnesium adenosine diphosphate significantly enhanced the inhibitory potency of ketamine racemate. The last transmembrane domain of SUR2 was essential for the full inhibitory effect of ketamine racemate. These results suggest that ketamine-induced inhibition of sarcolemmal KATP channels is mediated by the SUR subunit. These inhibitory effects of ketamine exhibit specificity for cardiovascular KATP channels, at least some degree of stereoselectivity, and interaction with intracellular magnesium adenosine diphosphate.


Stress is a pervasive factor in everyday life that critically affects development and functioning. Severe and prolonged stress exposure impairs homeostatic mechanisms, particularly associated with the onset of depressive illness. Brain food is aimed at preventing as well as treating a growing number of stress-related mental disorders. Some topics on the association of stress and nutrition is reviewed. (1) An increased activity of serotonergic neurons in the brain is an established consequence of stress. An increase in brain tryptophan levels on the order of that produced by eating a carbohydrate-rich/protein-poor meal causes parallel increases in the amounts of serotonin released into synapses. (2) Eating is thought to be suppressed during stress, due to anorectic effects of corticotrophin releasing hormone, and increased during recovery from stress, due to appetite stimulating effects of residual cortisol. (3) A strong inverse association between coffee intake and risk of suicide. (4) Night eating syndrome has been found to occur during periods of stress and is associated with poor results at attempts to lose weight and disturbances in the hypothalamic-pituitary-adrenal axis. (5) Dietary antioxidants present in fruits and vegetables may improve cognitive function. Therefore, it is concluded that the establishment of functional foods that correctly regulate stress response must be firmly based upon scientific knowledge and legal regulation.

The Journal of Medical Investigation : JMI


Endothelin-1(1 31) levels are increased in atherosclerotic lesions of the thoracic aorta of hypercholesterolemic hamsters

The novel vaso-constricting 31-amino acid-length endothelin-1 [ET-1(1-31)] is selectively produced by human mast cell chymase via its action on big ET-1. However, the pathological role of ET-1(1-31) in atherosclerosis remains unclear. The aim of this study was to clarify vasoconstrictive response and expression of ET-1(1-31) in atherosclerotic aorta. Syrian golden hamster, was used for preparing the atherosclerotic models by the administration of a high cholesterol diet (HC), treatment with the nitric oxide synthase inhibitor (Nomega-nitro-L-arginine methylester, L-NAME) alone, or both (HC and L-NAME) for 40 weeks. Early atherosclerosis was observed in the case of HC or L-NAME alone treatments respectively and severe atherosclerosis was observed in the case of combined HC and L-NAME treatment. Vasoconstriction induced by ET-1(1-31) was not altered by the atherosclerotic changes, but the expression pattern of ET-1(1-31) was different at each stage of the atherosclerotic aorta. ET-1(1-31) was observed rarely in normal aortas or in early atherosclerotic lesions, but ET-1(1-31) expression was dramatically increased in aortic neointima and adventitia in a state of atherosclerosis with severe inflammation. ET-1(1-31) might play in a role of promoting atherosclerosis, and especially be involved in inflammatory mediation during the progression of atherosclerosis.


Molecular Mechanisms of the Inhibitory Effects of Bupivacaine, Levobupivacaine, and Ropivacaine on Sarcolemmal Adenosine Triphosphate-sensitive Potassium Channels in the Cardiovascular System.

Sarcolemmal adenosine triphosphate-sensitive potassium (KATP) channels in the cardiovascular system may be involved in bupivacaine-induced cardiovascular toxicity. The authors investigated the effects of local anesthetics on the activity of reconstituted KATP channels encoded by inwardly rectifying potassium channel (Kir6.0) and sulfonylurea receptor (SUR) subunits. The authors used an inside-out patch clamp configuration to investigate the effects of bupivacaine, levobupivacaine, and ropivacaine on the activity of reconstituted KATP channels expressed in COS-7 cells and containing wild-type, mutant, or chimeric SURs. Bupivacaine inhibited the activities of cardiac KATP channels (IC50 = 52 microm) stereoselectively (levobupivacaine, IC50 = 168 microm; ropivacaine, IC50 = 249 microm). Local anesthetics also inhibited the activities of channels formed by the truncated isoform of Kir6.2 (Kir6.2 delta C36) stereoselectively. Mutations in the cytosolic end of the second transmembrane domain of Kir6.2 markedly decreased both the local anesthetics' affinity and stereoselectivity. The local anesthetics blocked cardiac KATP channels with approximately eightfold higher potency than vascular KATP channels; the potency depended on the SUR subtype. The 42 amino acid residues at the C-terminal tail of SUR2A, but not SUR1 or SUR2B, enhanced the inhibitory effect of bupivacaine on the Kir6.0 subunit. Inhibitory effects of local anesthetics on KATP channels in the cardiovascular system are (1) stereoselective: bupivacaine was more potent than levobupivacaine and ropivacaine; and (2) tissue specific: local anesthetics blocked cardiac KATP channels more potently than vascular KATP channels, via the intracellular pore mouth of the Kir6.0 subunit and the 42 amino acids at the C-terminal tail of the SUR2A subunit, respectively.


Impairment of gastrointestinal motility by nitrate administration: evaluation based on electrogastrographic changes and autonomic nerve activity

Nitrates decrease the tone of the lower oesophageal sphincter, and may thus induce gastro-oesophageal reflux. In the present study, we evaluated electrogastrographic changes and heart-rate variability before and after the administration of nitrates. In 15 patients with chest pain treated with nitrates, electrocardiography and percutaneous electrogastrography were performed before and after administration of nitrates. Autonomic nervous system function was evaluated by spectral analysis of heart-rate variability and serial changes in low frequency and high frequency power, and the low frequency/high frequency ratio were compared. Electrogastrograms were analysed by obtaining peak power amplitudes and their dominant frequencies. After the administration of nitrates (isosorbide dinitrate), high frequency power, an index of parasympathetic nervous activity, was significantly decreased, whereas the low frequency/high frequency ratio, an index of sympathetic nervous activity, was significantly increased. The mean peak amplitude of the electrogastrogram significantly increased postprandially both before and after treatment. After isosorbide dinitrate treatment, however, mean peak amplitudes after a meal were significantly lower than those obtained before treatment. The mean dominant frequency of the electrogastrogram did not vary before and after treatment. The present study suggests that nitrates inhibit gastrointestinal motility by decreasing autonomic nervous activity.


Taurine alters respiratory gas exchange and nutrient metabolism in type 2

To assess the effect of taurine supplementation on respiratory gas exchange, which might reflect the improved metabolism of glucose and/or lipid in the type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Male OLETF rats (16 weeks of age) were randomly divided into two groups: unsupplemented group and taurine-supplemented (3% in drinking water) group. After 9 weeks of treatment, indirect calorimetry and insulin tolerance tests were conducted. The amounts of visceral fat pads, tissue glycogen, the blood concentrations of glucose, triacylglycerol, taurine, and electrolytes, and the level of hematocrit were compared between groups. A nondiabetic rat strain (Long-Evans Tokushima Otsuka) was used as the age-matched normal control. The indirect calorimetry showed that the treatment of OLETF rats with taurine could reduce a part of postprandial glucose oxidation possibly responsible for the increase of triacylglycerol synthesis in the body. Taurine supplementation also improved hyperglycemia and insulin resistance and increased muscle glycogen content in the OLETF rats. Supplementation with taurine increased the blood concentration of taurine and electrolyte and fluid volume, all of which were considered to be related to the improvement of metabolic disturbance in OLETF rats. Taurine supplementation may be an effective treatment for glucose intolerance and fat/lipid accumulation observed in type 2 diabetes associated with obesity. These metabolic changes might be ascribed, in part, to the alteration of circulating blood profiles, where the improved hyperglycemia and/or the blood accumulation of taurine itself would play roles.


Long Term Follow-up in Japanese Public Office Workers of the Influence of Blood Pressure on ECG Changes

The relationship between annual changes in blood pressure (BP) and the electrocardiogram (ECG) was studied to clarity what factors give early detection of complications and predict the outcome of therapy. The influence of BP on the ECG was assessed in 830 Japanese office workers. Those with hypertension (HT) more frequently developed left atrial and ventricular overload compared with normotensive subjects. In addition, those with borderline HT (systolic pressure 140-160 mmHg and/or diastolic pressure 90-95 mmHg) and even those with lower blood pressure (systolic pressure 130-140 mmHg and/or diastolic pressure 85-90 mmHg) developed left atrial and ventricular overload more frequently than normotensive subjects. Based on these results, BP should be closely followed up when routine systolic and diastolic pressure levels exceed 130 mmHg and 85 mmHg, respectively, in persons in their 40 s to 50 s and the goal of antihypertensive therapy should be lower than reported previously.


KATP Channel Knockout Mice Crossbred with Transgenic Mice Expressing a Dominant-Negative Form of Human Insulin Receptor have Glucose Intolerance but not Diabetes

Impaired insulin secretion and insulin resistance are thought to be two major causes of type 2 diabetes mellitus. There are two kinds of diabetic model mice: one is a K(ATP) channel knockout (Kir6.2KO) mouse which is defective in glucose-induced insulin secretion, and the other is a transgenic mouse expressing the tyrosine kinase-deficient (dominant-negative form of) human insulin receptor (hIR(KM)TG), and which has insulin resistance in muscle and fat. However, all of these mice have no evidence of overt diabetes. To determine if the double mutant Kir6.2KO/hIR(KM)TG mice would have diabetes, we generated mutant mice by crossbreeding, which would show both impaired glucose-induced insulin secretion and insulin resistance in muscle and fat. We report here that: 1) blood glucose levels of randomly fed and 6 h fasted double mutant (Kir6.2KO/hIR(KM)TG) mice were comparable with those of wild type mice; 2) in intraperitoneal glucose tolerance test (ipGTT), Kir6.2KO/hIR(KM)TG mice had an impaired glucose tolerance; and 3) during ipGTT, insulin secretion was not induced in either Kir6.2KO/hIR(KM)TG or Kir6.2KO mice, while the hIR(KM)TG mice showed a more prolonged insulin secretion than did wild type mice; 4) hyperinsulinemic euglycemic clamp test revealed that Kir6.2KO, Kir6.2KO/hIR(KM)TG and hIR(KM)TG mice, showed decreased whole-body glucose disposal compared with wild type mice; 5) Kir6.2KO, but not Kir6.2KO/hIR(KM)TG mice had some obesity and hyperleptinemia compared with wild type mice. Thus, the defects in glucose-induced insulin secretion (Kir6.2KO) and an insulin resistance in muscle and fat (hIR(KM)TG) were not sufficient to lead to overt diabetes.


Molecular mechanisms of the inhibitory effects of propofol and thiamylal on sarcolemmal adenosine triphosphate-sensitive potassium channels.

Both propofol and thiamylal inhibit adenosine triphosphate-sensitive potassium (KATP) channels. In the current study, the authors investigated the effects of these anesthetics on the activity of recombinant sarcolemmal KATP channels encoded by inwardly rectifying potassium channel (Kir6.1 or Kir6.2) genes and sulfonylurea receptor (SUR1, SUR2A, or SUR2B) genes. The authors used inside-out patch clamp configurations to investigate the effects of propofol and thiamylal on the activity of recombinant KATP channels using COS-7 cells transfected with various types of KATP channel subunits. Propofol inhibited the activities of the SUR1/Kir6.2 (EC50 = 77 microm), SUR2A/Kir6.2 (EC50 = 72 microm), and SUR2B/Kir6.2 (EC50 = 71 microm) channels but had no significant effects on the SUR2B/Kir6.1 channels. Propofol inhibited the truncated isoform of Kir6.2 (Kir6.2DeltaC36) channels (EC50 = 78 microm) that can form functional KATP channels in the absence of SUR molecules. Furthermore, the authors identified two distinct mutations R31E (arginine residue at position 31 to glutamic acid) and K185Q (lysine residue at position 185 to glutamine) of the Kir6.2DeltaC36 channel that significantly reduce the inhibition of propofol. In contrast, thiamylal inhibited the SUR1/Kir6.2 (EC50 = 541 microm), SUR2A/Kir6.2 (EC50 = 248 microm), SUR2B/Kir6.2 (EC50 = 183 microm), SUR2B/Kir6.1 (EC50 = 170 microm), and Kir6.2DeltaC36 channels (EC50 = 719 microm). None of the mutants significantly affects the sensitivity of thiamylal. These results suggest that the major effects of both propofol and thiamylal on KATP channel activity are mediated via the Kir6.2 subunit. Site-directed mutagenesis study suggests that propofol and thiamylal may influence Kir6.2 activity by different molecular mechanisms; in thiamylal, the SUR subunit seems to modulate anesthetic sensitivity.


A patient with Wallenberg's syndrome induced by severe cough

A 45-year-old man developed severe cough with cervical pain. The patient was unable to hold an upright position. The origin of the right posterior inferior cerebellar artery was not enhanced by angiography. MRI showed a high signal intensity string-like structure of the right vertebral artery. In young patients, Wallenberg's syndrome related to mild head trauma has been reported. However, none of the previous studies related to vertebral arterial dissection was induced by severe cough. When cervical pain is present in young patients with severe cough, MRI should be performed to evaluate the possibility of vertebral arterial dissection.


Localization of the 31-amino-acid endothelin-1 in hamster tissue

Endothelin (ET)-1(1-31) is a novel vasoconstrictor peptide produced by human mast cell chymase, which selectively cleaves big ET-1 at the Try(31)-Gly(32) bond. We investigated the localization of ET-1(1-31) in various hamster tissues by immunohistochemistry and compared it to the distribution of ET-1(1-21). We found that the localization and amount of ET-1(1-31) were different from those of ET-1(1-21) in each tissue. ET-1(1-31)-like immunoreactivities (IR) in the heart, lung, and adrenal gland were observed in the same areas as ET-1(1-21) but were significantly weaker, suggesting that ET-1(1-31) might play a role only in mast cell/chymase-related pathological conditions in these tissues. In the liver, ET-1(1-31)-like IR was strongly detected in Kupffer cells where ET-1(1-21)-like IR was seen more weakly. In the kidney, ET-1(1-31)-like IR was slightly higher than ET-1(1-21). These results suggest that ET-1(1-31) might have physiological roles distinct from those of ET-1(1-21) in some hamster tissues.


Detection of coronary arterial microvascular discorders using 99mTc-tetrofosm in uptake increase during exercise and coronary blood flow velocity patterns obtained by magnetic resonance imaging.

This study reports an evaluation of coronary arterial blood flow patterns in patients with diabetes mellitus and healthy subjects using magnetic resonance coronary angiography (MRCA). Twenty patients with diabetes mellitus (DM group) and 20 healthy subjects (N group) were studied using MRCA and myocardial SPECT images using (99m)Tc-tetrofosmin (TF). The rate of change in myocardial TF uptake was measured during a 1-day protocol of exercise and rest. Initial and delayed exercise single photon emission computed tomography (SPECT) images were acquired 30 min and 3 h after injection (370 MBq of TF) (TF1 and TF2, respectively). Thereafter, 740 MBq of TF was administered intravenously, again, and resting SPECT images (TF3) were acquired 30 min later. The myocardial counts of these three points of acquisition were defined, and the rate of change of myocardial TF uptake between exercise and rest was determined. The % increase in uptake was significantly lower in the DM group than in the N group in all myocardial segments. The average coronary arterial diastolic velocity determined using MRCA was slightly lower in the DM group than in the N group, and the average systolic peak velocity (ASPV) was slightly greater in the DM group than in the N group, although these values were not statistically significant. The diastolic/systolic velocity ratio (DSVR) in the DM group was significantly lower than that in the N group ( P < 0.05). There was a significant correlation between DSVR and % uptake increase ( r = 0.605, P < 0.05). These results indicate that the measurements made using MRCA and the % uptake increase measured using TF myocardial scintigraphy represent a potentially useful noninvasive method for diagnosing microvascular dysfunction in diabetic patients.


Influence of sleep apnea on autonomic nervous activity and QT dispersion in patients with essential hypertension and old myocardial infarction

Sleep apnea syndrome (SAS) is an important cardiovascular risk factor in patients with hypertension or myocardial infarction (MI). We evaluated the influence of SAS on autonomic nervous activity and QT dispersion in patients with hypertension or coronary artery disease with old MI. A portable sleep polygraph was attached to 30 healthy volunteers (N group), 30 patients with essential hypertension (HT group), and 30 patients with old myocardial infarction (MI group) to serially record oronasal respiration, tracheal sound, thoracic respiratory movement, and percutaneous arterial oxygen saturation. In addition, a digital Holter ECG was used to examine heart rate variability during nighttime sleep. Heart rate variability was analyzed by obtaining low-frequency (LF) power, high-frequency (HF) power, the LF/HF ratio, and very low-frequency (VLF) power. Dispersion of QT intervals was obtained by CM5 and CM1 leads. VLF and LF powers were significantly higher in the HT-SAS group (hypertensive patients with SAS) than the N and HT-NSAS groups (hypertensive patients without SAS). The HF power was significantly lower in the HT-NSAS group than the N group, but the decrease in HF power in hypertension was not observed in the HT-SAS group. The LF/HF ratio was significantly higher in the HT-NSAS group than the N group, and this value was further increased in the HT-NSAS group. Percutaneous arterial oxygen saturation was decreased, and QT dispersion was significantly increased in the MI group during sleep apnea episodes. More severe autonomic nervous dysfunction and increased QTc dispersion were observed in hypertensive patients with SAS during episodes of apneas and hypopneas compared to those without SAS. These findings suggest that SAS may be associated with the future development of cardiac events.


Evaluation of myocardial sympathetic nerve function in patients with mitral valve prolapse using iodine-123-metaiodobenzylguanidine myocardial scintigraphy.

Mitral valve prolapse (MVP) is closely related to myocardial sympathetic nerve function. This study evaluated the presence of impaired myocardial sympathetic nerve function by Iodine-123-metaiodobenzylguanidine (MIBG) scintigraphy in ten patients with MVP. For comparison, 15 healthy subjects without heart disease were investigated (control group). Single photon emission computed tomography (SPECT) and anterior planar myocardial scintigraphy were performed 15 min (initial images) and 3 hours (delayed images) after injection of MIBG (111 MBq). The location and degrees of reduced tracer uptake were evaluated. Myocardial MIBG uptake was quantified by uptake ratio of the heart (H) to upper mediastinum (M) on the anterior planar images (H/M). Percentage washout of MIBG in nine sectors of all oblique slices along the short-axis was calculated. The washout rates were higher at the inferoposterior and septal segments in patients with anterior leaflet prolapse, and at inferoposterior and lateral segments in patients with posterior leaflet prolapse. The bull's eye map showed increased washout rate in the apical and posteroseptal basal segments. There was no significant difference in the H/M ratio between MVP patients and the control group. These results indicate that MIBG can be used to evaluate localized myocardial sympathetic nerve function in MVP.


心磁図法は循環器病診療に貢献できるのか?

心磁図法は循環器病診療に貢献できるのか?

The Journal of Japan Biomagnetism and Bioelectromagnetics Society


Does Coronary Artery Stenting for Acute Myocardial Infarction Improve Left Ventricular Overloading at the Chronic Stage?

In the present study, we evaluated whether stenting is useful for cardiac overloading, using ANP, BNP, and sup99m/supTc-tetrofosmin myocardial scintigraphy. It has been reported that coronary artery stenting is useful for cardiac functions for acute myocardial infarction (AMI). The subjects were 110 patients with AMI successfully treated by direct angioplasty. These patients were subgrouped into two groups: the S group (underwent stenting; 54 patients) and the P group (underwent POBA alone; 56 patients). Extent scores reflecting decreased myocardial blood flow were calculated at myocardial areas showing a radioactivity count of less than -2 × standard deviations compared to the database of normal subjects.The ratio of extent scores to defect scores (extent/defect ratio) was compared between the P and S groups. Both ANP and BNP levels in the S group were lower than in the P group at the chronic stage (1 and 3 months after reperfusion therapy). Moreover, the end-diastolic volume index from the left ventriculography 3 months after reperfusion therapy was significantly larger in the P than the S group. The extent/defect ratio was significantly lower in the P group (2.8 ± 0.2) than the S group (3.5 ± 0.3), suggestive of a microcirculation disorder. These results suggest that cardiac overloading and left ventricular remodeling are decreased more by stenting than by POBA alone, probably because stenting prevents decreased myocardial blood flow around the infarct myocardium.br


Clinical Study on the Effects of Nizatidine on Gastric Motillity and Cardiac Autonomic Function

Nizatidine (CAS 76963-41-2, Acinon), an H2 receptor antagonist, not only inhibits acid secretion but also improves gastrointestinal motility. However, autonomic nervous function has not been studied in detail using electrogastrography (EGG). In the present study, two protocols were adopted to study nizatidine's effects on cardiac autonomic function and gastric motility. Protocol I--Acute: "Group C-I": 10 healthy volunteers received a single oral dose of nizatidine 150 mg. Protocol II--Chronic: "Group DM without N": 15 patients with diabetes mellitus (DM) were observed prior to administration of nizatidine. "Group DM with N": The same 15 patients with DM received nizatidine 300 mg/day for more than 30 days. "Group C-II": This control group was composed of 15 healthy volunteers not receiving nizatidine. In all groups, EGGs were recorded before and after a meal, and autonomic nervous function and QT interval of ECG dispersions were simultaneously evaluated. In Group C-I, nizatidine significantly increased the peak power amplitude of 3 cycles/min (cpm) frequency, but did not significantly change the dominant frequency of the 3-cpm waves. In Group DM with N, nizatidine administration significantly increased the peak power amplitude from 2.4 cpm or a lower frequency (bradygastria) to 3 cpm. Prior to nizatidine administration but after eating a meal, the peak power amplitude on EGG was not increased in Group DM without N. In Group DM with N, however, the EGG peak power amplitude increased to levels similar to those of the healthy subjects (Group C-II). Neither the single nor the chronic administration of nizatidine significantly prolonged the QT interval or increased the QT dispersion. A spectral analysis of heart rate variability showed that nizatidine administration, whether acute or chronic, did not significantly change the indices of autonomic nervous activity. Nizatidine may promote gastric emptying by inhibiting acetylcholine esterase, thus increasing cholinergic activity, and by acting directly on gastric smooth muscle. The results indicate that because nizatidine increases gastric motility without exerting a negative influence on the autonomic nerves, it may be a useful drug in patients with diabetic neuropathy.


Decreased blood levels of lactic acid and urinary excretion of 3-methylhistidine after exercise by chronic taurine treatment in rats

Taurine is reported to increase contractility of skeletal muscle and cardiac myocyte, which can increase exercise performance. The present study aimed to clarify taurine's effect on chronic endurance exercise, especially accumulation of lactic acid (LA), a marker of fatigue and ability of aerobic exercise, and urinary secretion of 3-methylhistidine (3-MH), a marker of muscle breakdown in rats. After exercise blood levels of LA and urinary excretion of 3-MH were significantly increased and this increase was significantly less in those with chronic treatment of taurine. Taurine treatment also significantly decreased fat accumulation and blood levels of cholesterol and triglyceride, which might improve insulin resistance and utilization of fat and glucose. These results indicate taurine treatment is useful for reducing physical fatigue and muscle damage during exercise training in rats, presumably due to antioxidant property and improvement of muscle and cardiac functions by taurine.

Journal of Nutritional Science and Vitaminology


2型糖尿病患者における呼吸商-体重増加から見た糖尿病治療薬における呼吸商の意義

2型糖尿病患者における呼吸商-体重増加から見た糖尿病治療薬における呼吸商の意義

The Journal of Metabolism and Clinical Nutrition


Increased Insulin Sensitivity and Hypoinsulinemia in APS Knockout Mice

A tyrosine kinase adaptor protein containing pleckstrin homology and SH2 domains (APS) is rapidly and strongly tyrosine phosphorylated by insulin receptor kinase upon insulin stimulation. The function of APS in insulin signaling has heretofore remained unknown. APS-deficient (APS(-/-)) mice were used to investigate its function in vivo. The blood glucose-lowering effect of insulin, as assessed by the intraperitoneal insulin tolerance test, was increased in APS(-/-) mice. Plasma insulin levels during fasting and in the intraperitoneal glucose tolerance test were lower in APS(-/-) mice. APS(-/-) mice showed an increase in the whole-body glucose infusion rate as assessed by the hyperinsulinemic-euglycemic clamp test. These findings indicated that APS(-/-) mice exhibited increased sensitivity to insulin. However, overexpression of wild-type or dominant-negative APS in 3T3L1 adipocytes did not affect insulin receptor numbers, phosphorylations of insulin receptor, insulin receptor substrate-1, or Akt and mitogen-activated protein kinase. The glucose uptake and GLUT4 translocation were not affected by insulin stimulation in these cells. Nevertheless, the insulin-stimulated glucose transport in isolated adipocytes of APS(-/-) mice was increased over that of APS(+/+) mice. APS(-/-) mice also showed increased serum levels of leptin and adiponectin, which might explain the increased insulin sensitivity of adipocytes.


Supplementation of L-arginine improves hypertension and lipid metabolism but not insulin resistance in diabetic rats

Nitric oxide (NO) plays an important role in glucose and lipid metabolism. We previously reported that NO synthesis inhibitors, such as NG-nitro-L-arginine methyl ester (L-NAME), deteriorate insulin sensitivity and lipid metabolism, while the addition of L-arginine reverses this deterioration. L-arginine is a precursor of NO, and is used as a supplement in the US. In the present study, we evaluated whether the administration of L-arginine alone improves insulin resistance and serum lipid levels in insulin-resistant and hypertriglycemic rat models. Diabetic rats were divided into 3 groups: the control (Cont) group (standard diet), the L-NAME group (diet containing L-NAME), and the Arg group (diet containing L-arginine). After 4 weeks of breeding, urinary NOx, glucose infusion rate (GIR), glucose and lipid tolerance tests were performed. Urinary NOx levels were significantly lower in the L-NAME group than in the Cont group. The GIR in the L-NAME group was significantly lower than that in the Cont group, suggesting increased insulin resistance. However, the administration of L-arginine did not influence insulin resistance in the Arg group. Oral lipid administration significantly increased plasma triglyceride levels in the L-NAME group and plasma triglyceride levels were significantly lower in the Arg group than in the Cont group. The area under the curve of plasma triglyceride levels after oral lipid administration was larger in the L-NAME group than in the Cont group. The administration of L-NAME increased insulin resistance and decreased lipid metabolism. L-arginine significantly increased urinary NO secretion but did not improve insulin resistance, although it did improve lipid metabolism. These findings suggest that supplementation of L-arginine cannot improve insulin resistance in diabetic rats probably due to increased insulin secretion by L-arginine.


Injection of the Insulin receptor alpha subunit increases blood glucose levels in mice

Using the expression vector of the truncated human insulin receptor (hIR), we have constructed a stable Chinese hamster ovary (CHO) cell line which secretes the His-tagged alpha subunit (insulin-binding domain) of hIR into medium. To examine characteristics of the His-tagged hIRalpha, we purified the protein secreted from the CHO cells. The His-tagged hIRalpha was glycosylated and processed a dimer. The molecule bound insulin with an affinity similar to that of the intact hIR. The His-tagged full length of hIR was autophosphorylated by insulin stimulation in CHO cells. Injection of the purified His-tagged hIRalpha into veins of mice increased in the concentration of blood glucose within 30 min. The intraperitoneal glucose tolerance test (ipGTT) done after injection of the purified His-tagged hIRalpha showed evidence of a marked hyperglycemia. These findings provide direct evidence that the presence of hIRalpha in the blood stream inhibits insulin actions by binding with plasma insulin.

Biochemical and Biophysical Research Communications


Effects of Epalrestat, an Aldose Reductase Inhibitor, on Diabetic Neuropathy and Gastroparesis

Diabetic patients with severe autonomic nervous disorder show delayed gastric emptying accompanied by diabetic gastroparesis, which decreases the electric activity of the stomach associated with gastric motility. It is reported that epalrestat, an aldose reductase inhibitor, is useful for treating diabetic neuropathy. Therefore, we evaluated whether this drug improves the decreased gastric motility in diabetic patients. The present study evaluated the electrogastrograms (EGG) and autonomic nervous activity in 15 healthy volunteers (N group), and in 15 diabetic patients before and after the administration of epalrestat (DM group). Autonomic nervous activity was evaluated by spectral analysis of heart rate variability. The EGGs were recorded before and after oral administration of epalrestat (3 months or more) in the DM group. The dominant frequency of EGG was 3 cycles/min (cpm) in the N group. However, these 3 cpm waves disappeared with bradygastria, and postprandial increases in the peak powers of EGG were not observed in the DM group. Both the amplitude of 3 cpm waves and the postprandial peak powers were significantly increased after the administration of epalrestat. The parameters of autonomic nervous activities (LF power, HF power, and the LF/HF ratio) were significantly lower in the DM group before the administration of epalrestat than in the N group. However, these parameters were improved after the administration of epalrestat. Since gastroparesis is a form of diabetic dysautonomia, complication by gastroparesis may influence blood sugar control and the absorbance of oral antidiabetics. Epalrestat significantly increased the amplitude of 3 cpm waves on EGG and improved the spectral analytical parameters of heart rate variability. These findings suggest that epalrestat is useful for the treatment of diabetic gastroparesis.


Comparison of gastric peristalsis inhibition by scopolamine butylbromide and glucagon:evaluation by electrogastrography and analysis of heart rate variability

Activation of glucagon receptors of the smooth muscle membrane suppresses gastric peristalsis. We evaluated autonomic nervous activity by two methods, electrogastrography (EGG) and analysis of heart rate variability, to compare the inhibiting effects of glucagon and scopolamine butylbromide on gastric peristalsis. Heart rate variability, EGG, and blood catecholamine levels were measured before and after administration of glucagon (G group), scopolamine butylbromide (SB group), or physiological saline (C group). Autonomic nervous function was evaluated using spectral analysis of heart rate variability, and low frequency (LF) and high frequency (HF) power; the LF/HF ratios were also determined. After administration of scopolamine butylbromide, HF power, an index of parasympathetic nervous activity, decreased; and the LF/HF ratio, an index of sympathetic nervous activity, increased. In contrast, no significant change was observed in autonomic nervous activity after administration of glucagon. The peak power amplitudes of the EGG decreased significantly in the G and SB groups after intramuscular injection, but the difference between the groups was not significant. Furthermore, the dominant frequency increased significantly in the G and SB groups after injection. Serum catecholamine levels showed no significant changes after administration of scopolamine butylbromide or glucagon. Inhibition of gastric peristalsis by glucagon via glucagon receptors on smooth muscles did not influence autonomic nervous activity, unlike the results obtained after administration of scopolamine butylbromide. Therefore, glucagon may be safe for use with elderly patients and those with cardiopulmonary complications.


Autonomic nervous dysfunction in patients with liver cirrhosis using 123I-metaiodobenzylguanidine myocardial scintigraphy and spectrum analysis of heart-rate variability

Journal of Gastroenterology and Hepatology