Electrophysiological effects of nicardipine hydrochloride on the isolated sinoatrial and atrioventricular nodes of the rabbit.
The electrophysiological effects of nicardipine-HCl, a new calcium antagonist and potent vasodilator, were studied in the isolated sinoatrial (SA) and atrio-ventricular (AV) nodes of the rabbit in an oxygenated Tyrode solution at 35 degrees C using an intracellular microelectrode technique. Nicardipine-HCl decreased the spontaneous rate of the SA node and prolonged sinus recovery time, dose-dependently. The effective refractory period (ERP) and functional refractory period (FRP) of the AV node and AV conduction time (A-H interval) were also prolonged by nicardipine-HCl in a dose-dependent manner. In conclusion, nicardipine-HCl has electrophysiological effects on the SA and the AV node similar to those of other calcium antagonists in the excised and superfused rabbit heart.
D000818:Animals; D001283:Atrioventricular Node / Q000187:drug effects* / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006329:Heart Conduction System / Q000187:drug effects*; D066298:In Vitro Techniques; D008839:Microelectrodes; D009529:Nicardipine; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D011817:Rabbits; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D012849:Sinoatrial Node / Q000187:drug effects* / Q000502:physiology
D002121:Calcium Channel Blockers; D011725:Pyridines; D009529:Nicardipine; D009543:Nifedipine