EFFECTS OF EXERCISE ON THE CORONARY BLOOD FLOW, HEART RATE AND BLOOD PRESSURE OF TRAINED DOGS WITH DENERVATED AND PARTIALLY DENERVATED HEARTS

Abstract

Observations were made on the coronary blood flow, heart rate and blood pressure of trained dogs after the following procedures: (1) bilateral sympathetic ganglionectomy, from the 8th costal interspace anteriorly including the stellate ganglion; (2) double cervical vagotomy; (3) right vagotomy followed by left vagotomy; (4) cardiac sympathectomy and right cervical vagotomy, followed by left cervical vagotomy. Blood flow in the circumflex branch of the left coronary artery was observed by use of the thermostromuhr. Blood pressure was recorded optically from a cannulated femoral or carotid artery. The heart rate was observed electrocardiographically. The effects of exercise on animals that had sympathectomized hearts were not essentially different from results obtained in animals that had innervated hearts. In both series, exercise produced increased coronary blood flow, pulse rate and blood pressure. The observations were made 24-124 days after sympathetic ganglionectomy. The effects of exercise were very similar in animals on which complete cardiac denervation had been performed and those lacking only the vagi. Loss of the vagi affected cardiac acceleration profoundly. Vagotomized hearts increased only about 10-20 beats each min. with increments in the rate of work. This was true whether or not the sympathetic nerves were present. In the absence of marked acceleration and elevation of blood pressure the coronary blood flow was not affected by exercise. In animals that had vagotomized or totally denervated hearts the coronary blood flow appeared to be influenced chiefly by the blood pressure.