LIPID-PEROXIDATION ASSESSMENT OF FREE-RADICAL PRODUCTION FOLLOWING RELEASE OF OBSTRUCTIVE UROPATHY

Purpose: To identify if free radicals were released following relief o f ureteric obstruction. Materials and Methods: Free radical production was assessed by a high performance liquid chromatography assay of mal ondialdehyde (MDA) in a 24-hour complete unilateral ureteric obstructi on model in Wistar rats. Results: In the first experiment, a rise grea ter than 20% above prerelease levels in renal venous malondialdehyde l evels was observed at 8, 15, 22, and 30 minutes following release. At 45 and 60 minutes, levels were similar to the prerelease levels. In th e second experiment, renal venous samples taken before release and at 10 and 20 minutes after release in control and obstructed groups (n = 7) identified a significant difference (T = 10 minutes p = 0.006 and T = 20 minutes p = 0.045). A significant MDA rise following release occ urred only in the obstructed group (obstruction group: MDA level T = 0 min. 1.01 mu mol./l. +/- 0.13, T = 10 min. 2.12 mu mol./l. +/- 0.3 p = 0.016, T = 20 min. 2.09 mu mol./l. +/- 0.28 p = 0.016. Control group : T = 0 min. 1.13 mu mol./l. +/- 0.23, T = 10 min. 1.05 mu mol./l. +/- 0.18 p = 0.95, T = 20 min. 1.23 mu mol./l. +/- 0.19 p = 0.67). In the third experiment, an attempt was made to block free radical release w ith allopurinol. No statistical difference between the control and obs tructed groups with allopurinol was noted at 20 minutes after release. A Kruskal Wallace two-way analysis identified a significant differenc e between experiments two and three at both time periods (p = 0.049). Conclusion: This study suggests, for the first time, that free radical s are released after relief of ureteric obstruction and that this rele ase is partially attenuated by allopurinol pretreatment.