Intracellular electrophysiological alterations in canine cardiac conducting tissue induced by aprindine and lignocaine.

The effects of aprindine and lignocaine (lidocaine USP) were compared on intracellularly recorded potentials from normal canine conducting tisues. Only aprindine produced marked depression of the maximum rate of rise (Vmax) of action potentials elicited at normal cycle lengths (1000 ms). Both compounds, however, produced enhanced depression of Vmax at short cycle lengths or at short S1-S2 coupling intervals at normal membrane resting potential. Both lignocaine and aprindine shorten the action potential duration (APD) and effective refractory period (ERP) but increase the EPR/APD ratio. These effects are easily reversible upon perfusion with drug-free solution only in the case of lignocaine.