The effect of chlorpromazine on the mechanogram, electrocardiogram and membranopotential of the frog heart]

The action of chloropromazine in concentrations between 10(-6) and 10(-3) M was studied with regard to its effect on contractility, ECG, and membrane potential of the isolated frog heart. In concentrations above 10(-6) a depressive influence on the amplitude of contraction was observed; the speed of contraction was reduced. The heart rate showed negatively chronotropic changes. In the ECG there was a striking expansion of the PQ interval. The membrane potential was reduced under the effect of chloropromazine depending on the concentration used. The negative influence on mechanical and bioelectrical parameters of the myocardium is interpreted to be due to membrane-related factors. A vagus-like effect is discussed, particular importance being attached to the mechanisms of the "slow-channel" system.