Do renal nerves chronically influence renal function and arterial pressure in spinal rats?

Previous studies have demonstrated that renal nerve activity has acute effects on renal function in rats with cervical spinal cord transection (CST). The present study tested the hypothesis that renal nerves chronically influence renal and cardiovascular function in CST rats. Three groups of conscious Sprague-Dawley rats were studied: renal denervated plus CST (RDNX + CST), sham RDNX plus CST (sham + CST), and sham RDNX plus sham CST (intact). CST or sham CST surgeries were performed 8 days after RDNX or sham RDNX. Sodium and water intakes were fixed by intravenous infusion. Mean arterial pressure (MAP) and plasma renin activity (PRA) were measured before and for 9 days after CST/sham CST. In addition, urine flow, urinary sodium excretion, and urine pH were measured in the two groups of CST rats. One day after CST, MAP decreased approximately 25 mmHg in both RDNX + CST and sham + CST groups. PRA had fallen approximately 50% 1 day after CST and was not different between CST groups. PRA remained depressed throughout the study. There were no differences between sham + CST and RDNX + CST rats in any of the renal or cardiovascular variables measured after CST. In summary, we found no evidence for a chronic effect of renal nerves on renal function or arterial pressure in CST rats.