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) pr olonged the action potential duration (APD) and effective refractory p eriod (ERP) in ventricular muscles and Purkinje fibers. The ratio of E RP/APD(90) increased. The slopes of phase 1 and phase 3 of action pote ntial were flattened. Gallanilide (10 mu M) decreased the maximal risi ng rate and amplitude of the action potential. The depressant effect o n the maximal rising rate was frequency-dependent. These results sugge st that gallanilide possesses both class I and III antiarrhythmic acti ons, which may be the electrophysiological basis of its antiarrhythmic effect. (C) 1997 Wiley-Liss, Inc.