Renal nerves mediate changes in contralateral renal blood flow after extracorporeal shockwave lithotripsy

Renal blood flow falls in both kidneys following delivery of a clinical dose of shockwaves (SW) (2000 SW, 24 kV, Dornier HM3) to only one kidney. The role of renal nerves in this response was examined in a porcine model of renal denervation. Six-week-old pigs underwent unilateral renal denervation. Nerves along the renal artery of one kidney were identified, sectioned and painted with 10% phenol. Two weeks later the pigs were anesthetized and baseline renal function was determined using inulin and PAH clearances. Animals then had either sham-shockwave lithotripsy (SWL) (group 1), SWL to the innervated kidney (group 2) or SWL to the denervated kidney (group 3). Bilateral renal function was again measured 1 and 4 h after SWL. Both kidneys were then removed for analysis of norepinephrine content to validate the denervation. Renal plasma (RPF) flow was significantly reduced in shocked innervated kidneys (group 2) and shocked denervated kidneys (group 3). RPF was not reduced in the unshocked denervated kidneys of group 2. These observations suggest that renal nerves play a pivotal role in modulating the vascular response of the contralateral unshocked kidney to SWL, but only a partial role, if any, in modulating that response in the shocked kidney.