Sustained capacity for exercise in dogs after complete cardiac denervation

Abstract

The capacity for exercise was studied in dogs before and after cardiac denervation by the technic of regional neural ablation. Measurements were made of cardiac output (indicator-dilution technic and electromagnetic flowmeter), heart rate, oxygen consumption, oxygen saturation of mixed venous blood and aortic blood pressure before and during work of graded severity. Each animal was studied on several occasions over a period of several months. No deterioration in the capacity for exercise was noted after cardiac denervation; as in the control period, at maximal levels of work there was a three- to fourfold increase in cardiac output and an eight- to tenfold increase in oxygen consumption. In contrast to the normal dog in which increase in cardiac output was achieved by an increase in heart rate, in the dog with cardiac denervation increase in cardiac output was effected principally by an increase in stroke volume.