Altered expression of antioxidant enzymes and level of lipid peroxide in rat kidney exposed to ischemia-reperfusion injury

To evaluate the possible role of free radical injury in acute renal ischemiareperfusion model - activities, protein and m-RNA levels of catalase (CAT), glutathione peroxidase (GPX), CuZn- and Mn-superoxide dismutase (SOD) and lipid peroxide (LPO) were measured in kidney exposed to 30, 60 and 90 min of ischemia followed by 2 or 24 hr reperfusion in rat kidneys Small changes were observed in these antioxidant enzymes in a group exposed to 30 min of ischemia, and these were normalized to the control level after 24 hr reperfusion in both activities as well as protein levels. However, in a group exposed to 60 min of ischemia CAT, GPX and CuZnSOD activities were significantly decreased and LPO were increased particularly following 24 hr reperfijsion. On the other hand, the decrease of MnSOD activity was relatively smaller than any other antioxidant enzymes. Similar tendencies were observed in a group exposed to 90 min of ischemia but the changes were more profound. Protein levels of CAT in 60 and 90 min groups were decreased to 46% and 38% of the control, respectively, following 24 hr reperfusion. The level of MnSOD protein were relatively unaffected. The m-RNA levels for CAT and CuZnSOD were significantly decreased, while MnSOD were increased in tissues exposed to 60 or 90 min of ischemia followed by 24 hr reperftision. These results suggest that this down regulation of transcription/ translation of antioxidant enzymes (CAT, CuZnSOD) may contribute towards the free radical injury observed in pathophysiology of ischemia-reperfiision injury.