THE ELECTROPHYSIOLOGIC EFFECTS OF ENDOTHELIN - A PATCH-CLAMP STUDY INGUINEA-PIG VENTRICULAR MYOCYTES

To study the electrophysiologic effects of endothelin-1 (ET-1), we use d patch clamp and glass microelectrode techniques to investigate the e ffects of ET-1 on cardiac L-Ica, Ik and Ik(2) in guinea pig ventricula r myocytes, The prolongation of APD(50) was induced and EADs was trigg ered by 50 nM ET-1 perfusion. L-Ica and Ik were enhanced by various ET -1 concentration from 1 to 50 nM I with dose-dependence. Their steady- state activations of L-Ica and Ik shifted left with ET-1 concentration increments, ET-1 elicited a kind of GTP-dependent inward rectifier K- current having a mean conductance of 82.36+/- 1.27 pS, The open time and close time (both interburst intervals and burst durations) abbrevi ated with ET-1 concentration increase. The results suggested that EADs -ET evoked was ascribed to the prolongation on the plateau level, whi ch resulted from L-Ica inhancement. The ET- evoked inward rectifier K current should be further studied.