普罗帕酮及其对映体对豚鼠心室乳头肌动作电位的影响

用细胞内微电极法研究普罗帕酮消旋体及两对映体对豚鼠右心室乳头肌快反应动作电位（FAP）和慢反应动作电位（SAP）的作用. 普罗帕酮消旋体及两对映体均浓度依赖性地降低FAP和SAP的0相最大除极速率（V_max）和动作电位幅值（APA）, 3药≤3 μmol·L^-1时均延长动作电位时程（APD）. 10 μmol·L^-1时， APD₅₀ 和APD₉₀反缩短至给药前水平，(R)-普罗帕酮延长FAP的APD₂₀而(S)-普罗帕酮则无影响,两组间有显著性差异（P<0.05）. 3药对FAP和SAP静息电位, V_max, APA, APD₅₀及APD₉₀影响均无显著性差异. 结果表明, 普罗帕酮两对映体的钠通道阻滞作用及钙拮抗作用无差异，对心肌动作电位平台期内向钠和/或钙离子流的作用可能表现立体选择性.

Effects of propafenone and its enantiomers on action potentials of isolated guinea pig papillary muscles

The effects of propafenone and its enantiomers on action potential (AP) of guinea pig right ventricle papillary muscles were studied by using intracellular microelectrodes. (R/S), (R) and (S) propafenone reduced the maximal upstroke velocity of phase 0 (V_max) and AP amplitude (APA) of fast response AP (FAP) and slow response AP (SAP) concentration-dependently. They all prolonged action potential duration (APD) of FAP and SAP at ≤3 μmol·L^-1. At 10 μmol·L^-1, there was no further prolongation of APD₅₀ and APD₉₀, APD₂₀ of FAP was prolonged by (R)-propafenone but was not significantly changed by (S)- propafenone, and there were statistically significant difference between them (P<0.05). There were no statistical differences in other effects on FAP and SAP among them. It is concluded that (R)- and (S)-propafenone exert equal sodium channel blocking effect and calcium antagonistic action, but they may show stereospecific effects on the slow inactivating sodium current and/or slow calcium inward current of plateau phase of AP.