NATRIURESIS CAUSED BY INCREASED CAROTID NA+ CONCENTRATION AFTER RENALDENERVATION

The renal effects of a selective estimated 3 mM increase in the concen tration of Na+ in blood perfusing the brain was investigated in consci ous dogs with surgically denervated kidneys. In split-infusion experim ents the concentration of Na+ in carotid plasma was increased by a bil ateral carotid infusion of hypertonic NaCl combined with an infusion o f distilled water into the caval vein. In control experiments the same load of NaCl and water was administered as an isotonic solution into the carotid and jugular vessels. Peak rate of Na+ excretion was signif icantly higher during split infusion (156 +/- 19 mu mol/min) compared with control (89 +/- 14 mu mol/min). Renal excretion of urodilatin inc reased in both series. Renal excretion of endothelin immunoreactivity increased significantly more during split infusion (20 +/- 6 pg/min) t han during control (9 +/- 3 pg/min). It is concluded that the natriure tic response to minute increases in Na+ concentration of carotid plasm a is intact after renal denervation. Furthermore, endothelin may be in volved in the excess excretion observed.