Keitaro Hashimoto

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The present study was designed to investigate what kinds of adaptation occurred in the canine chronic AV block model, which has been used to study torsade de pointes (TdP). Dogs at 7-10 days (acute phase) and 28-56 days (chronic phase) after AV block were assessed. Ventricular effective refractory period and monophasic action potential duration were(More)
In order to compare and clarify the effects of various antiarrhythmic drugs when given as monotherapy, we reevaluated our previous data on antiarrhythmic drugs and recalculated antiarrhythmic plasma concentrations of drugs for several canine arrhythmia models. We used three spontaneously occurring arrhythmias: a) digitalis-, b) two-stage coronary ligation-,(More)
HMG-CoA reductase inhibitors (statins) have been shown to decrease cardiovascular mortality. Since ventricular tachyarrhythmias are closely related to cardiovascular mortality, we tested effects of the hydrophilic statin pravastatin and the lipophilic statin fluvastatin in a rat arrhythmia model of ischemia/reperfusion and simultaneously measured serum(More)
The purpose of this study was to evaluate a telemetry system for examining QT evaluation in the conscious free-moving guinea pig using 10 reference compounds whose effects on human QT interval are well established: 8 positive references (bepridil, terfenadine, cisapride, haloperidol, pimozide, quinidine, E-4031 and thioridazine), and 2 negative references(More)
The Na+-Ca2+ exchange (NCX) system plays a pivotal role in regulating intracellular Ca2+ concentration in cardiomyocytes, neuronal cells, kidney and a variety of other cells. It performs a particularly important function in regulating cardiac contractility and electrical activity. One of the leading NCX inhibitors is KB-R9743 (KBR) that appears to exhibit(More)
Sodium-calcium exchange (NCX) is one of the major regulators of intracellular Ca(2+) concentration in cardiac myocytes. The bi-directional and electrogenic property of NCX raises a question about whether NCX is involved in arrhythmias. We reviewed the role of NCX in cardiac triggered activity in limited experimental conditions: the digitalis-induced(More)
A new beverage made of red wine vinegar and grape juice (Budo-no-megumi) was developed for people who wish to take effective amount of both polyphenols and vinegar. Since the beverage was recently demonstrated to exert hypotensive effect in rats, we analyzed its underlying mechanisms in this study. Sprague-Dawley rats were anesthetized with pentobarbital,(More)
Y-27632, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride monohydrate, is a selective Rho-associated kinase inhibitor, which has been suggested to possess multiple clinical applications based on the in vitro observations. Since information regarding in vivo cardiovascular effects of Y-27632 is still limited, we assessed(More)
SEA0400 (2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline), a novel and selective inhibitor of Na+/Ca2+ exchanger, was investigated for its possible antiarrhythmic effects on arrhythmias of Ca2+ overload induced by coronary ligation/reperfusion and by digitalis in the dog. SEA0400 (1.0 mg/kg) did not change the hemodynamics but slightly prolonged(More)
A simple in vivo closed-chest atrial fibrillation (Af) model of rats was developed. Af was reproducibly induced by transesophageal atrial burst pacing for 30 s in each of the pentobarbital-anesthetized rats, whereas the cardiohemodynamic condition as well as the inducibility and duration of Af episode was stable over time. Moreover, the anti-Af effect of(More)