Changes in sensitivity of aortic baroreceptors under the influence of the sympathetic nervous system

Abstract

The dependence of activity of the aortic baroreceptors on the pressure in the aorta during stimulation of the branch from the stellate ganglion innervating the aortic baroreceptor zone was studied in experiments on cats. Stimulation of the sympathetic branch was shown not to change the threshold of activity of the baroreceptors (80 mm Hg) or their activity within the range from 80 to 140 mm Hg. With higher pressures in the aorta, stimulation of the sympathetic branch reduced baroreceptor activity, as a result of which the curve of baroreceptor activity as a function of pressure became flatter and reached maximal activity at a higher intraortic pressure (on the average 32 mm Hg higher). The mechanisms of the action of the sympathetic nerves on baroreceptor sensitivity and the physiological significance of this phenomenon are discussed.