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 blood volume expansion was investigated by measurement of urine volume, sodium and osmolar excretion rates, sodium p-aminohippurate and free water clearances, and systemic haemodynamic and plasma hormone (atrial natriuretic peptide, arginine vasopressin and plasma renin activity (PRA)) changes in ten control and ten renal-denervated chloralose-anaesthetized mongrel dogs. Following renal denervation, blood volume expansion caused a similar increase in sodium excretion to that in the control group. Renal denervation resulted in systemic vasodilatation and decreased PRA. During fluid loading the right atrial pressure and pulmonary capillary wedge pressure were significantly higher in the control group. In the control group, volume expansion caused a large fall in PRA, whereas in the renal-denervated dogs, PRA remained suppressed. We conclude, from the fact that natriuresis is preserved after renal denervation, that this response is not mediated by a reflex with efferent limb in the renal nerves.