A fourth class of anti-dysrhythmic action? Effect of verapamil on ouabain toxicity, on atrial and ventricular intracellular potentials, and on other features of cardiac function

Abstract

Anti-dysrhythmic drugs can be classified as having three main classes of action; (1) direct interference with depolarization (local anaesthetic type); (2) anti-sympathetic action, by neurone blockade or transmitter competition; (3) delay of repolarization. Verapamil has recently been reported to be anti-dysrhythmic, but the present analysis of its pharmacological effects has indicated that this property cannot be attributed to any of the above three actions. It is speculated that it may possess a fourth class of action, interference with calcium conductance, with the implication that calcium currents may contribute to abnormal impulse formation.