The reduced renal blood flow observed after exposure to shock wave lithotripsy involves intact renal nerves

Treating one kidney with high-energy acoustic shock waves reduces blood flow 65% in that kidney and 33% in the contralateral unshocked kidney. We tested the hypothesis that renal nerves were involved in this response. Six-week old pigs underwent unilateral renal denervation. Nerves along the renal artery of one kidney were cut and the artery was painted with 10% phenol. After 2 weeks, the pigs were anesthetized and bilateral renal function was determined using inulin and PAH (para-aminohippurate) clearance. Glomerular filtration rate (GFR, inulin clearance) and renal blood flow (PAH clearance) were measured both before and after lithotripsy to the lower pole of the innervated kidney (2000 shocks, 24 kV, unmodified Dornier HM-3) or sham lithotripsy. Both kidneys were then removed to measure norepinephrine content in the tissue. Norepinephrine levels were significantly reduced (more than 90%) in denervated kidneys indicating complete denervation. As expected, blood flow and GFR fell (approximately 50%) after lithotripsy in the innervated shocked kidneys, but did not fall significantly in denervated contralateral kidneys or in sham lithotripsy animals. Results suggest that renal nerves mediate the fall in contralateral renal function after lithotripsy. [Work supported by NIH P01 DK43881. ]