Effects of dauricine on transmembrane potential of ischemic and non-ischemic Purkinje fibers and ventricular muscles from infarcted canine hearts

Dauricine (Dau) 1-30 mumol/L produced the concentration-dependent depression of APA, Vmax, MDP, and RP, and prolongations of APD90 of Purkinje fibers (PF) and epicardial ventricular muscles (VM) from both infarcted and non-infarcted zones. The ERP was lengthened only in non-ischemic PF and VM, and APD50 in non-ischemic PF, non- and ischemic VM. The prolonging effects of Dau on APD and ERP of ischemic PF were much less than those of non-ischemic ones, and its depressing effect on the Vmax of ischemic VM was markedly greater than that of non-ischemic VM. The results suggest that Dau exerts its anti-arrhythmic effect through further depressing conduction of ischemic zone.