The effect of ketamine on transmembrane potentials of purkinjé fibres of the pig heart

Abstract

The action of ketamine upon spontaneously active and electrically driven Purkinjé fibres of the moderator band of the pig heart has been studied using a floating micro electrode technique. Ketamine hydrochloride altered the transmembrane potential in a dose-related and reversible manner. Concentrations of 1× 10-5M were subthreshold whereas 5 × 10-5M and 1× 10-4M slowed the frequency and increased the action potential duration of spontaneous preparations, actions consistent with an anti arrhythmic effect. Higher concentrations of 5 × 10-4M ketamine initially led to a shortening of the action potential duration, then failure of the original spontaneous activity. During recovery pacemaker-like activity developed associated with a loss of resting membrane potential. In electrically driven preparations 5 × 10-4M ketamine significantly shortened the duration of the action potentials between evoked potentials and markedly augmented the response to adrenaline, actions consistent with an arrhythmogenic effect. These findings suggest a basis for isolated reports of cardiac side effects. © 1974 John Sherratt and Son Ltd.