THE RESPONSES IN RENAL NERVES TO STIMULATION OF ATRIAL RECEPTORS, CAROTID SINUS BARORECEPTORS AND CAROTID CHEMORECEPTORS

Abstract

The reflex reduction in activity in renal sympathetic nerves in response to distension of small balloons in the pulmonary vein-atrial junctions was stuided in dogs anesthetized with chloralose; the carotid sinuses were isolated and perfused with blood. In the 1st group of dogs, the response to distension of the balloons was studied at different levels of carotid sinus pressure. In 13 preparations of renal nerves in 8 dogs the response was not significantly influenced when the mean carotid sinus pressure was changed from 9.5 [K-pascal] to 17.5 [K-pascal], despite marked changes in control frequencies of activity in the nerves. In the 2nd group of dogs, the response to distension of the balloons was studied when the carotid sinuses were perfused alternately with arterial and venous blood. In 6 preparations of renal nerves in 5 dogs the response was not significantly influenced when the blood perfusing the carotid sinuses was changed, despite marked changes in control frequencies of activity in the nerves. In a 3rd group of dogs, the reflex reduction in activity in renal nerves in repsonse to a step increase in pressure in 1 carotid sinus was examined at different levels of pressure in the contralateral carotid sinus. In 6 preparations of renal nerves in 5 dogs the response to an increase in pressure in 1 carotid sinus was significantly reduced when the mean pressure in the contralateral sinus was changed from 8.7 to 17.1 kPa. Apparently, there is no interaction between the projections of atrial receptors and carotid sinus baroreceptors or carotid chemoreceptors in their convergence on the same efferent renal neurons.