Effects of dauricine and lidocaine alone or combined on electrophysiological properties of canine Purkinje fibers.

Dauricine (Dau) 1 to 30 mumol/L produced the concentration-dependent depressions in the APA, Vmax, MDP, and prolongations of APD50 and APD90 as well as ERP of the isolated canine cardiac Purkinje fibers (PF). The automaticity and excitation were significantly reduced at concentration of 30 mumol/L. The effects of Dau on all action potential parameters of PF were observed at all stimulation frequencies (60, 75, 100, 150 beats/min). Lidocaine (Lid) markedly shortened APD50 of PF at concentration of 30 mumol/L and also shortened APD90, ERP and significantly depressed APA, Vmax at 100 mumol/L. When perfused in combination with Dau, Lid appreciably shortened APD50 and APD90, and lightly abbreviated ERP prolonged by Dau.