In vivo quantitation of regional versus systemic SWL-induced free-radical activity

Abstract

Renal tissue injury in shock wave lithotripsy (SWL) may be attributed directly to vascular trauma and indirectly to ischemia-reperfusion with resultant free-radical formation. We have employed a microdialysis system to assess areas of renal injury in relation to the site of SWL treatment. Swine were assigned to a control group (N=3) and a SWL-treated group (N=3). Microdialysis probes were inserted into the parenchyma of the lower pole, upper pole of right kidney, and the lower pole of left kidney. Seventy-two hours following probe insertion, baseline dialysate samples were collected, after which SWL was administered exclusively to the right kidney lower pole in the treated group, using a Dornier Compact S lithotripter at its highest intensity. Dialysate samples were collected every 1000 shocks. It was found that SWL caused a significant increase in free-radical activity, as measured by lipid peroxidation, in the right lower pole, followed by a moderate increase in the right upper pole. Yet, no free-radical activity was noted in the left kidney. These findings suggest that SWL-induced free-radical activity is localized and confined to the ipsilateral kidney. There does not appear to be systemic circulating nephrotoxic factors following SWL treatment. [Work supported by NIH.]