Effect of unilateral renal denervation on bilateral renal response to saline loading in anteroventral third ventricle-lesioned rats.

Our previous experiments demonstrated that lesions in the anteroventral third ventricle (AV3V) region of the brain attenuated natriuretic and diuretic response to saline loading in rats. To further assess if renal nerves are involved in this impaired response, we compared the effect of acute unilateral renal denervation on the response to saline loading in AV3V-lesioned and intact rats. Rats with electrolytic ablation in the AV3V region were prepared 4 weeks prior to experiments. The arterial blood pressure (BP) and bilateral renal responses to acute expansion of plasma volume by saline loading (0.388 ml/min for 1 h) were measured in rats under pentobarbital anesthesia. Saline loading before renal denervation induced a smaller increase in bilateral renal excretion of sodium and water in AV3V-lesioned rats than in control rats. Acute renal denervation produced ipsilateral natriuresis and diuresis without causing significant change in the excretory functions of the contralateral kidneys in both the lesioned and the control rats. BP and glomerular filtration rate of both groups of rats remained unaltered. The denervation-induced natriuretic and diuretic responses in the lesioned rats were not significantly different from those of the control rats. Subsequent saline loading increased bilateral renal excretion of sodium and water in both groups of rats. However, the previously observed attenuation of natriuretic and diuretic responses to saline loading in rats with AV3V lesions was abolished after renal denervation. These results suggest that the integrity of the AV3V region is necessary for normal regulation of sodium and water balance. Furthermore, there is a functional connection between the renal nerve and the AV3V region in modulating renal excretion during volume expansion.