川楝素对豚鼠乳头状肌电和机械特性的影响(英文)

Effects of toosendanin on electric and mechanical properties of guinea pig papillary muscles

川楝素(TS)浓度依赖性地使快反应电位复极至90％的时程(APD_(90)延长。用BaCl_2阻断I_(kl),可取消TS延长APD_(90)的作用.TS使慢反应电位的APD延长和收缩力(FC)增强。用BaCl_2后,可取消TS的上述作用。CdCI_2取消TS增强FC的作用,但延长APD的作用存在。提示,TS抑制I_(kl),其正性肌力作用是继发于APD的延长及钙通道的失活减慢。

Effects of toosendanin (TS) on the action potentials and contractile force in guinea pig papillary muscles were examined using a standard microelectrode technique. TS concentration-dependently increased the action potential duration at 90% repolarization (APD90) of the fast action potentials. In the presence of a Ik1 channel blocker BaCl2, the effects of TS on lengthening the APD90 were completely abolished, thereby suggesting that TS inhibited the inward rectifier K+ current /ki- The APD and contractile force of amino- phylline-induced slow action potentials were potentiated by TS in a concentration-dependent manner. In the presence of BaCl2, both effects of TS were completely abolished. The effect of TS on enhancing contractile force was abolished by the addition of CdCl2, with the prolongation of APD preserved. Thus, TS selectively inhibited the inward rectifier K+ current Ik1 with a positive inotropic effect, resulting from a delay in Ca channel inactivation which was secondary to delay in ventricular repolarization.