Electrophysiological effects of carocainide (770207) on canine ventricular muscle and Purkinje fibers.

Carocainide is a new benzofuran derivative showing antiarrhythmic properties in animal models. In isolated papillary muscles and Purkinje fibers it decreases the maximum rate of rise of the action potential and in Purkinje fibers it decreases the plateau amplitude and the duration of the action potential. Carocainide increases the ratio of the effective refractory period to the action potential duration at 90% of repolarization, shifts the membrane responsiveness curve towards more negative membrane potentials and slows down the recovery of the maximum rate of rise of the action potentials of the Purkinje fibers. Carocainide also increases the conduction time at the Purkinje papillary muscle junction.