Atrial receptor discharge during acute coronary occlusion in the dog

Atrial type B receptor activity was studied in dogs undergoing occlusion of the main left coronary artery. Prior to coronary artery occlusion, receptor discharge exhibited a characteristic pattern of electrical activity in which each burst started at the time the atrium began to fill and ceased at the time of atrioventricular valve opening. Coronary artery occlusion resulted in an increase in left atrial pressure and a concomitant increase in atrial receptor discharge. Increase in left atrial pressure by intravascular volume expansion resulted in an increase in receptor discharge which was similar to that observed during coronary occlusion. In many instances, receptor discharge became continuous and did not exhibit any cardiac rhythmicity. It can be concluded from the results presented that the increase in atrial type B receptor discharge during coronary artery occlusion results from the associated increase in atrial pressure and not from the effects of coronary ischemia per se.