Electrophysiological effects of guan-fu base A on action potentials of guinea pig ventricular papillary muscles
Abstract
Guan-fu base A (GA), an alkaloid first isolated in China, 50 mg.L-1 decreased the action potential amplitude and the maximal rate of depolarization (Vmax) of guinea pig papillary muscles in vitro. GA shortened the action potential period at 90% repolarization (APD90) without significant effect on the effective refractory period (ERP), resulting in an increased ERP/APD90 ratio. GA 50 mg.L-1 also slowed the conduction speed. The inhibiting effect of GA on Vmax showed frequency- and potential-dependent manners.
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