摘要
川楝素灌流豚鼠乳头状肌,玻璃微电极记录胞内动作电位,机械-电换能器记录其收缩。结果:川楝素使异丙肾上腺素(ISO)诱发的慢反应电位(SAP)的时程(APD)延长,其收缩力(FC)增强,呈浓度依赖性。对氯化钡诱发的SAP,延长APD和增强FC的作用消失。用氯化镉部分阻断慢内向电流(I_(si)),川楝素增强FC的作用减弱,但延长(APD)的作用仍在。提示川楝素可能同时抑制心肌的延迟整流K^+电流(I_k)及内向整流K^+电流(I_(kl)),其正性肌力作用是继发于(APD)的延长及I_(si)的失活减慢。
The effects of toosendanin (TS) on the slow action potentials (SAP) induced by isoproterenol(ISO) and BaCl_2 and the force of contraction (FC) were observed in guinea-pig papillary muscles. Theaction potential duration (APD) and FC of ISO-induced SAP were potentiated by TS in a concentra-tion-dependent manner. In the BaCl_2-induced SAP,the effects of TS on lengthening APD and enhanc-ing FC were not observed. It was suggested that TS might inhibit the delayed rectifier and the inwardrectifier currents (I_k and I_(kl). When the effectS of TS (2×10^(-5) g/ml) on lengthening APD and en-hancing FC were observed in ISO-induced SAP, the application of 50 μmol/L CdCl_2 to block I_(si) couldreduce prominently the FC-enhancing effect of TS, with the APD-prolonging effect preserved. Thus,itappeared that TS inhibited both the delayed rectifier K^+ current I_k and the inward rectifier K^+ currentI_(kl), with a positive inotropic effect, resulting from a delay in Ca^(2+) channel inactivation,secondary todelay in ventricular repolarization.
出处
《河南医科大学学报》
1993年第4期289-291,共3页
Journal of Henan Medical University
基金
国家自然科学基金 38970831
关键词
川楝素
乳头状肌
动作电位
钾通道
toosendanin
papillary muscles
action potentials
myocardial contraction
ion channels
guinea--pig
