NATRIURESIS CAUSED BY BLOOD-VOLUME EXPANSION IN DOGS IS NOT MEDIATED BY THE RENAL NERVES

The influence of renal denervation on the renal response to rapid bloo d volume expansion was investigated by measurement of urine volume, so dium and osmolar excretion rates, sodium p-aminohippurate and free wat er clearances, and systemic haemodynamic and plasma hormone (atrial na triuretic peptide, arginine vasopressin and plasma renin activity (PRA )) changes in ten control and ten renal-denervated chloralose-anaesthe tized mongrel dogs. Following renal denervation, blood volume expansio n caused a similar increase in sodium excretion to that in the control group. Renal denervation resulted in systemic vasodilatation and decr eased PRA. During fluid loading the right atrial pressure and pulmonar y capillary wedge pressure were significantly higher in the control gr oup. In the control group, volume expansion caused a large fall in PRA , whereas in the renal-denervated dogs, PRA remained suppressed. We co nclude, from the fact that natriuresis is preserved after renal denerv ation, that this response is not mediated by a reflex with efferent li mb in the renal nerves.