Observations on Responses of the Heart to Catecholamine-Depletion Produced by Reserpine

The data obtained indicate that spontaneously beating untreated control and catecholamine-depleted isolated guinea pig and cat hearts have a similar heart rate, developed tension and (in the cat) coronary flow. These parameters are similar for the two groups both initially and over a 3-hour period of observation. Moreover, the cardiac reserve of depleted guinea pig hearts was not lower than their controls at higher perfusion pressure. In addition, severe catecholamine depletion was unaccompanied by any histological alterations and bilateral vagotomy did not alter reserpine-induced bradycardia in the intact guinea pig. These results, coupled with reports on cardiac-denervated animals, necessitate a revaluation of the physiological significance of endogenous cardiac catecholamines in non-pathological states.