THE ROLE OF OXYGEN-DERIVED FREE-RADICALS AND THE EFFECT OF FREE-RADICAL SCAVENGERS ON SKELETAL-MUSCLE ISCHEMIA-REPERFUSION INJURY

The aim of this study was to clarify the role of oxygen-derived free r adicals and the effect of free radical scavengers on skeletal muscle i schemia/reperfusion injury. Male Wistar rats were divided into a compl ete ischemia group (C-group) and an incomplete ischemia group (IC-grou p) and each animal was subjected to 2h of ischemia and 1h of reperfusi on. In an attempt to decrease reperfusion injury, the rats were given free radical scavengers either as allopurinol 50 mg/kg for 2 days or a s superoxide dismutase 60,000 units/kg plus catalase 500,000 units/kg. Tissue malondialdehyde, a product of lipid peroxidation, was measured as an indicator of free radicals, with higher levels indicating highe r concentrations of free radicals. The malondialdehyde level in the ga strocnemius muscle after 1h of reperfusion increased significantly in both groups when compared to the levels before and 2h after ischemia, although there was no significant difference between the two groups. T he water content of the gastrocnemius muscle and serum creatinine phos phokinase MM isoenzyme (CPK-MM) in both groups, and GOT in the C-group , increased significantly after 1h of reperfusion when compared the va lues before and 2h after ischemia. In the C-group, these values were s ignificantly higher than in the IC-group. The administration of free r adical scavengers suppressed the increase in malondialdehyde in the ga strocnemius muscle after reperfusion in both groups. The increase in w ater content and CPK-MM after reperfusion was also suppressed by free radical scavengers in the IC-group, but not in the C-group. These find ings suggest that ischemic damage predominates in complete severe isch emia/reperfusion injury, whereas reperfusion injury predominates in in complete mild ischemia/reperfusion injury.