Electrophysiological effects of gallanilide on cardiac ventricular and Purkinje fibers

The effects of gallanilide on action potentials were studied in swine ventricular muscles, Purkinje fibers, and guinea pig papillary muscles by conventional microelectrode techniques. Gallanilide (1-10 mu M) prolonged the action potential duration (APD) and effective refractory period (ERP) in ventricular muscles and Purkinje fibers. The ratio of ERP/APD(90) increased. The slopes of phase 1 and phase 3 of action potential were flattened. Gallanilide (10 mu M) decreased the maximal rising rate and amplitude of the action potential. The depressant effect on the maximal rising rate was frequency-dependent. These results suggest that gallanilide possesses both class I and III antiarrhythmic actions, which may be the electrophysiological basis of its antiarrhythmic effect. (C) 1997 Wiley-Liss, Inc.