Ventricular Function in Cardiac-Denervated and Cardiac-Sympathectomized Conscious Dogs

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Abstract
The role of the autonomic nervous system in ventricular function was studied in conscious animals when either the cardiac nerves or the sympathetic nerves to the heart had been eliminated. Regional neural ablation was used to denervate the heart, and blockade of the cardiac sympathetic nerves was performed with propranolol. A reduction in the plateau of the ventricular output was seen in the cardiac-denervated animals (263 ml/min per kg) and in animals with beta-blockade (240 ml/min per kg) as compared with 318 ml/min per kg for the control curves. The difference in stroke volume in the cardiac-denervated animals and the beta-blocked animals at the plateau demonstrates that the chronically cardiac-denervated animal changes its ventricular output solely by a change in stroke volume, whereas the animal with beta-blockade changes heart rate and stroke volume in response to stress. Thus the beta-blocked animals increased their heart rate by a decrease in parasympathetic activity.