Cardiac Responses to Sympathetic Stimulation

Abstract

The cardiac responses to stimulation of sympathetic nerves to the heart were studied both in thoracotomized and in intact unanesthetized dogs. The changes in heart rate, left ventricular pressure, right and left ventricular dimensions and systemic arterial pressures were recorded. The powerful effects of sympathetic stimulation resemble cardiac responses to exercise more than those following administration of catecholamines. It is inferred that neural mechanisms may be more important for cardiac control during spontaneous activities than the circulating hormones.