The effect of verapamil and diltiazem on cardiac stimulant effect of adrenaline and calcium chloride on isolated frog heart

Abstract

BackgroundCalcium channel blockers block voltage dependent Ltype of calcium channel and thus reduce the frequency of opening of these channels in response to depolarization. The result is a marked decrease in transmembrane calcium current associated with long lasting relaxation of vascular smooth muscle, reduction in contractility in cardiac muscle, decrease in pacemaker activity in the SA node and decrease in conduction velocity in the AV node. Among Calcium channel blockers verapamil, is cardio selective, nifedipine is vascular smooth muscle selective, while diltiazem exhibits intermediate selectivity.MethodsIn the present study, the effect of two Ca⁺⁺ channel blocker, Verapamil and Diltiazem were compared on the isolated frog heart by using adrenaline & calcium chloride as standard on frog heart contractility.Results and conclusionAdrenaline and calcium chloride increased the amplitude of contraction of isolated perfused frog heart. The Ltype of Ca²⁺ channel blockers verapamil and diltiazem produced dose dependent (2μg, 4μg, 8μg, and 16μg) reduction in the amplitude of contraction produced by calcium chloride in isolated perfused frog heart. There was no statistical significant difference (p > 0.05) between the inhibitory effect of diltiazem and verapamil on calcium chloride induced contraction of isolated frog heart.