氨氯地平的心肌电生理作用及对触发活动的影响

目的　观察新的钙拮抗剂———氨氯地平对心肌快反应动作电位和触发活动的影响。方法　采用标准玻璃微电极细胞内记录方法观察不同浓度氨氯地平对豚鼠心肌快反应动作电位及异丙肾上腺素诱发的早期后除极和哇巴因诱发的延迟后除极及触发活动的作用。实验在同一细胞完成对照和药理作用。结果　氨氯地平10 μmol·L-1对动作电位时程明显缩短 (n =6 ,P <0 .0 5 ) ,用药前后APA、Vmax、ERP、DP3无变化 ;2 5 μmol·L-1氨氯地平可抑制异丙肾上腺素和哇巴因诱发的触发活动。结论　氨氯地平对异丙肾上腺素和哇巴因诱发的触发活动有一定的对抗作用 ,其机理与钙拮抗有关。

Effects of amlodipine on the electrophysiology of myocardium and triggered activity

Objective To study the effects of amlodipine on fast action potential in myocardium of guinea pig and isoproternenol induced early afterdepolarization (EAD) and ouabain-induced delayed afterdepolarization (DAD) and triggered activity (TA). Methods The standard intracellular glass microelectrode was used, the action of the drug was observed in the same cell.Results At 10?μmol·L -1 , amlodipine caused a significant shortening of the action potential duration and no significant changes in action potential amplitude (APA), the maximal rate of rise of phase 0 (Vmax), effective refractory period (ERP) and duration of phase 3 (DP3); at 25?μmol·L -1 , it markedly attenuated the development of EAD induced by 50?μmol·L -1 isoproternenol in the myocardium of left atrium and inhibited ouabain induced DAD and TA in papillary muscles of right ventricular.Conclusion Amlodipine has a direct inhibitory effect on calcium infux and may prevent or cure isoproternenol and ouabain induced triggered arrhythmias.