In vitro analysis of Ca-antagonistic effects of prenylamine as mechanisms for its cardiac actions.

Ca-antagonistic properties of prenylamine were studied using isolated guinea-pig and canine cardiac preparations. Prenylamine is a weak Ca-antagonist compared to nifedipine, verapamil and diltiazem. Lower doses of prenylamine slightly increased the tension, but higher doses decreased the tension of both the guinea-pig and canine cardiac preparations. It decreased the tension while maintaining the action potential of the normal guinea-pig atrial preparation and decreased both the tension and Ca-action potential of the depolarized guinea-pig atrial preparation. Similar to antiarrhythmic agents, prenylamine also decreased the max dV/dt of the normal guinea-pig atrial action potential.