ELECTRO-PHYSIOLOGICAL EFFECTS OF BUNAPHTINE IN GUINEA-PIG VENTRICULAR FIBERS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 246  (2) , 224-236
Abstract
The electrophysiological effects of bunaftine (BNA) in concentrations between 10-7-10-4 M were studied on action potential characteristics of guinea pig ventricular fibers. In fibers stimulated at constant rate (BNA .gtoreq. 10-5 M) did not change the resting membrane potential but significantly decreased the amplitude and maximum rate of rise of the action potential and shifted the membrane responsiveness and membrane reactivation curves downward and to the right. At concentrations .gtoreq. 10-6 M action potential duration and effective refractory period were prolonged. BNA decreased ventricular excitability and maximum following frequency and suppressed the pacemaker activity induced in ventricular muscle fibers by Ba ions or by adrenaline [epinephrine] but it did not modify the the Ca-mediated action potentials. The mechanism responsible for the in vivo antiarrhythmic action and side effects are discussed.