A comparative study of the ventricular escape phenomenon from vagal stimulation

ABSTRACT

The phenomenon of ventricular escape from continued vagal stimulation has so far not been satisfactorily explained. Recently, Friedman and Campos (1960) and Friedman and Bhagat (1962) have postulated that the phenomenon of vagal escape might be explained as the basis of the catecholamine content of the heart. We have tested this hypothesis by correlating the degree of vagal inhibition with that of the catecholamine content of the heart in different species of animals. The hearts were depleted of catecholamines by the administration of reserpine and the degrees of vagal influence on these hearts compared with that on control animals. There was no correlation between the total catecholamine content of the heart and the degree of vagal inhibition. However, in resepinised dogs and cats, guinea-pig and fish stimulation of the vagas resulted in a greater inhibition of the heart than in non-reserpinised animals.