Abstract 476: Renal Sensory Reinnervation Following Acute Renal Denervation.

It is known that efferent sympathetic nerves reinnervate the kidney following renal denervation (DNX). As there is evidence for lack of cardiac sensory reinnervation following heart transplantation, it has been thought that renal sensory nerves do not reinnervate following renal DNX. This absence of renal sensory reinnervation has been suggested to contribute to the chronic blood pressure reduction (3 years) in humans following renal DNX. However, whether renal sensory reinnervation occurs following acute renal DNX has not been thoroughly examined. Therefore, we assessed renal sensory innervation at multiple time points from 4 days to 12 wks following unilateral surgical DNX + application of phenol to the renal artery in normal Sprague Dawley rats. The contralateral innervated (INN) kidney served as control. Sensory innervation was determined as optical density (ImageJ) of the sensory nerves identified by immunohistochemistry using antibodies against the neuropeptides substance P and calcitonin-gene-related peptide (CGRP) in the renal pelvic wall, as it is a major site of renal sensory innervation. In INN kidneys, optical density of the sensory nerve fibers in the renal pelvic wall was unchanged over the 4 days - 12 wk period (n=17). In DNX kidneys, optical density of the substance P/CGRP containing sensory nerves was 3%, 30%, 50 % and 100% of the control contralateral INN kidney at 4 days, 2 wks, 4 wks and 12 wks, respectively, after DNX. Linear regression of optical density (DNX/INN) versus time yielded similar intercept and slope values for the substance P and CGRP containing sensory nerves (R 2 = 0.82 and 0.77, respectively, P<0.001 for both). Conclusion: in normal rats, sensory reinnervation of the renal pelvic wall is complete at 12 wks following acute surgical renal DNX.