Mn-SOD Immunoreactivities of Rectus Femoris Muscle of the Rat in Reperfusion Injury and the Effects of Alopurinol Pretreatment

ABSTRACT

It has been well known that ischemia reperfusion injury to skeletal muscle following an acute arterial occlusion causes significant morbidity and mortality. There are many causes of reperfusion injury, but the oxygen free radicals have a significant role. During ischemia the ATP is catalyzed to hypoxanthine anaerobically and hypoxanthine dehydrogenase is converted to xanthine oxidase under the presence of O2 resulting in the production of cytotoxic oxygen free radical, which are harmful to muscle. The reactivity of superoxide dismutase(SOD), one of the major antioxidant enzymes, is increased against the formation of the superoxide radical during reperfusion. SOD metabolyzes the superoxide radical to H2 O2 and O2.The severity of ischemic damage deports on the duration of muscle ischemia. The reversible changes in the muscle occur afar 2 hours of ischemia and recover within 24 hours after reperfusion. After 6 hours ischemia, irreversible damage occurs and causes necrosis of muscle. The authors performed the resent study to investigate the changes of Mn-SOD and the effects of allopurinol, the inhibitor of xanthine oxidase, by measuring the immunoreactivitiy of the ischemic reperfused rectus femoris muscle of rats after 2 hours and 6 hours ischemia and timely reperfusion. A total of 176 healthy spraque-Dawley rats weighing from 200 gm to 250 gm were used. Under urthane(3.0 gm/kg.,IP) anesthesia, a lower-abdominal incision was made and the left common iliac artery was ligated by using a vascular clamp for 2 hours and 6 hours. Rectus femoris muscle was obtained at 0 hour, 1 hour, 2 hours, 24 hours, and 48 hours after removal of the vascular clamp. The specimens were sectioned in 14micro miter thickness with a cryostat. The immunoreactivities of Mn-SOD were observed by using Mn-SOD antibodies. The result were as follows. 1. The immunoreactivies of Mn-SOD around sarcolemma were stronger than those on the sarcoplasm. 2. The immunoreactivities of Mn-S0D after 2 hours of ischemia increased to moderate or weak reactivities at 1 hour and 2 hours of reperfusion and returned to week or trace reactivities at 24 hours and 48 hours of reperfusion 3. The pretreatment of allopurinol decreased the immunoreactivies of Mn-SOD during reperfusion. The pattern of changes of SOD immunoreactivies were similar, but the range of changes significantly decreased. 4. The immunoreactivies of Mn-SOD after 6 hours of ischemia increased after 6 hours of ischemia increased after reperfusion and showed peak at 2 hours and 24 hours specimen. After 48 hours in the reperfused group, the reactivities slightly decreased. 5. After 6 hours in the ischemia-reperfused group, the pretreatment of allopurinol decreased the immunoreactivies of Mn-SOD during reperfusion, but the effects were weak. These results suggest that the immunoreactivities of the 6 hours ischemia reperfused group were higher than those of 2-hours ischemia reperfused group in the rectus femoris muscle of rats and that allopurinol pretreatment can be credited with decreasing ischemia reperfusion injury within a reversible period.