Objective: To investigate the effect of Jiaotaiwan on action potentials(AP) of isolated ventricular myocytes in guinea pig. Method: The myocytes were enzymatically obtained from the guinea pig hearts and the action potentials were examined by whole-cell patch clamp technique. Result: Jiaotaiwan (0.2% solusion) decreased the resting potential from (-85.91±6.24)mv to (-99.64±6.62) mv (n=8

P＜0.01)

increased action potential amptitude(APA) from (128.91±1.39)mv to (139.74±2.67)mv(n=8

P＜0.01)

shortened action potential duration of repolarization 50%(APD50) from (505.49±30.97)ms to (329.94±44.32)ms (n=8

P＜0.01)

shortened action potential duration of repolarization 90%(APD90) from (524.96±30.99)ms to (358.41±43.51)ms (n=8

P＜0.01)

extended action potential duration of repolarization 50% to repolarization 90%(APD50-90) from (16.56±1.48)ms to (27.31±3.62)ms (n=8

P＜0.01)

and slowed down the slope of phase 3(V3) from (-2.93±0.33)v.s-1 to (-1.95±0.28) v.s- (n=8

P＜0.01). 0.1% and 0.4% Jiaotaiwan on the various indicators of impact and 0.2% of the change in trend. Conclusion: Jiaotaiwan can induce the following influence for ventricular myocytes: decreased RP

increased APA

shortened APD50

shortened APD90

extended APD50-90 and V3 slowed down. The influences of Jiaotaiwan are likely linked with the electrophysiological mechanism of its anti-arrhythmic effect.