ANTIOXIDANT ENZYME STATUS OF ISCHEMIC AND POSTISCHEMIC LIVER AND ISCHEMIC KIDNEY IN RATS

The specific activity of seven enzymes involved in protecting tissue f rom oxidative stress was determined in rat kidneys subjected to 0, 2, 4, or 8 h of normothermic ischemia and in isolated rat livers during c ontrol perfusion, after 2 h ischemia, and after 2 h ischemia plus 1 h of reperfusion. In general, none of the antioxidant enzymes measured s howed any consistent variation throughout the ischemic period even tho ugh mitochondrial function was significantly decreased, indicating sub stantial cell injury. Glutathione peroxidase (Se-GSH-Px) activity rema ined constant during 8 h of ischemia, although a small (29%) increase above control activity was noted at 4 h of ischemia. Se-independent GS H-Px activity (non-Se-GSH-Px) and glutathione reductase (GSSG-Red) rem ained constant up to 8 h of ischemia, when we measured an increase of 158% above controls in non-Se-GSH-Px and a decrease of 35% relative to controls in GSSG-Red. In perfused livers, the only change in enzyme a ctivity after 2 h of ischemia was an increased GSSG-Red activity of 21 % above control. This increase persisted into the reperfusion phase (3 5% above control activity) and was accompanied by decreases in both fo rms of GSH-Px (28% Se-GSH-Px and 44% non-Se-GSH-Px).