Natriuresis caused by increased carotid Na+ concentration after renal denervation

The renal effects of a selective estimated 3 mM increase in the concentration of Na+ in blood perfusing the brain was investigated in conscious dogs with surgically denervated kidneys. In split-infusion experiments the concentration of Na+ in carotid plasma was increased by a bilateral carotid infusion of hypertonic NaCl combined with an infusion of 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 significantly higher during split infusion (156 +/- 19 mu mol/min) compared with control (89 +/- 14 mu mol/min). Renal excretion of urodilatin increased in both series. Renal excretion of endothelin immunoreactivity increased significantly more during split infusion (20 +/- 6 pg/min) than during control (9 +/- 3 pg/min). It is concluded that the natriuretic response to minute increases in Na+ concentration of carotid plasma is intact after renal denervation. Furthermore, endothelin may be involved in the excess excretion observed.