Yoshihiko Sakakibara

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Although fast sodium current (INa) plays a major role in the generation and conduction of the cardiac impulse, the electrophysiological characteristics of INa in isolated human ventricular myocytes have not yet been fully described. We characterized the human ventricular INa of enzymatically isolated myocytes using whole cell voltage-clamp techniques. Sixty(More)
The effects of optically pure d-nicotine were investigated as compared with those of the l-isomer. d-Nicotine showed qualitatively the same effects as the l-isomer in the ganglionic or neuromuscular sites and the relative potency of the d-isomer was approximately 0.06 in the case of rat blood pressure (elevation), approximately 0.2 in the cat superior(More)
Patch-clamp recording techniques have permitted measurement of the fast Na+ current (INa) in isolated cardiac cells from a number of species in recent years. However, there is still only very little information concerning human cardiac INa. The purpose of this study was to describe the kinetics of INa in normal-appearing, Ca(2+)-tolerant, enzymatically(More)
The effects of alpha adrenoceptor agonists and antagonists on the postsynaptic alpha receptors were examined in the dog basilar, mesenteric and renal arteries and the type of alpha adrenoceptors present was characterized. In the basilar artery, noradrenaline, clonidine and phenylephrine produced almost the same maximal contraction, the pD2 values being(More)
In the rabbit iris sphincter muscle, electrical transmural stimulation produced fast and slow components of contraction which were markedly attenuated by tetrodotoxin. The fast component was augmented by physostigmine and was abolished by atropine, while the slow component was little affected. Adrenergic and ganglionic blocking agents did not inhibit the(More)
The transmission mechanism of sympathetic neuroeffector was studied in the isolated dog basilar artery. Electrical transmural stimulation produced an initial contractile response which was followed by a transient relaxation or a late contraction, or both relaxation and contraction. These arteries showed a marked uptake of [3H]norepinephrine ([3H]NE) or(More)
Effects of guanabenz, a hypotensive agent, on the adrenergic mechanism were studied in isolated rabbit thoracic aorta and pulmonary artery and findings were compared with data obtained with clonidine and guanethidine. Guanabenz in concentrations higher than 10(-6) M produced weak contractions which were attenuated by phentolamine or yohimbine. Such(More)
Lidocaine is a Na+ channel blocker that is highly effective for the treatment of ventricular tachyarrhythmias, but is largely ineffective against atrial arrhythmias. If is not known if this differential efficacy is the result of differences in lidocaine inhibition of atrial v ventricular Na+ channels. The purpose of the present study was to characterize(More)
The effects of cinepazide, 1-[(1-pyrrolidinylcarbonyl)methyl]-4-(3,4,5-trimethoxycinnamoyl )piperazine hydrogen maleate, were studied in isolated dog cerebral arteries. Cinepazide in concentrations ranging from 10(-6) to 10(-5) M augmented the relaxing responses to ATP, adenosine and cAMP. However, this agent did not affect the relaxations induced by(More)
Although lidocaine block of cardiac Na+ current (INa) has been extensively studied in animal tissues, very little is known about its actions on human cardiac INa. We studied the effects of lidocaine (0.01-10 mM) on human atrial INa in single myocytes using whole-cell patch-clamp techniques. The dose-response relationship for lidocaine block at a low(More)