It has been well known that ischemia reperfusion injury to skeletal muscle following an acute arterial occlusion causes significant morbidity and mortality. The skeletal muscle, which contains high energy phosphate compounds, has ischemic tolerance. During the ischemia, the ATP is catalyzed to hypoxanthine anaerobically and hypoxanthine dehydrogenase is converted to xanthine oxidase.
During reperfusion, the hypoxanthine is catalyzed to xanthine by xanthine oxidase under 02 presence and that results in production of cytotoxic oxygen free radicals. So, the damage of skeletal muscle occurs during reperfusion. The permeability of the capillary, one of the major phenomenon in injured muscle, is increased by reactive oxygen released from the neutrophils and the arachidonate metabolites, which are catalyzed from the lipid component of the membrane structures by lipooxygenase during reperfusion. The reversible changes in the muscle occur after 2 hours of ischemia and reperfusion and recover within 24 hours. The irreversible damage, which is necrosis of muscle, occurs after 6 hours of ischemia and reperfusion.
The reactivity of superoxide dismutase(SOD), one of the antioxidant enzymes is increased against the formation of superoxide radical during the reperfusion. The SOD metabolizes the superoxide radical to Hz02 and 02. There are two types of SOD in the cell. The one of them is Cu,Zn-SOD in the cytoplasm and the other is Mn-SOD in the mitochondria. The author performs the present study to investigate the changes of SOD immunoreactivities in the soleus muscle of the rat after 2 hours or 6 hours of ischemia and timely reperfusion.
A total of 88 healthy Sprague-Dawley rats weighing from 200 gm to 250 grn were used as experimental animals. Under urethane(3.0g/kg., i.p.) anesthesia, lower abdominal incision was made and left common iliac artery were ligated by using vascular clamp for 2 hours. Soleus muscles were obtained at 0 hour, 1 hour, 2 hours, 24 hours 48 hours after the removal of vascular clamp. The specimens were sectioned in 14?m thickness with cryostat. The immunoreactivities of SOD by use of anti human Cu,Zn- and Mn-SOD antibodies were observed.
The results were as follows.
1. The immunoreactivities of SOD around sarcolemma were stronger than those in the sarcoplasm.
2. The immunoreactivities of SOD in the soleus muscles decreased a little after 2 hours of
ischemia and increased markedly after 6 hours of ischemia.
3. The immunoreactivities of Cu,Zn-SOD in the soleus muscle increased after 2 hours or 6 hours of ischemia and timely reperfusion. The immunoreactivities of Cu,Zn-SOD in the 6 hours of reperfused group were highest after 2 hours of ischemia. Those in the 2 hours of reperfused group were highest after 6 hours of ischemia. At 48 hours of reperfusion, immunoreactivities of Cu,Zn-SOD recovered after 2 hours of ischemia and those kept higher reactivities after 6 hours of ischemia.
4. The immunoreactivities of Mn-SOD in the soleus muscles increased after 2 hours or 6 hours of ischemia and timely reperfusion. At 48 hours of reperfusion, immunoreactivities of Mn-SOD recovered after 2 hours of ischemia and those were increased markedly after 6 hours of ischemia.
These results suggest that the immunoreactivities of SOD increased after 2 hours or 6 hours of ischemia and timely reperfusion. At 48 hours of reperfusion the immunoreactivities of SOD recover after 2 hours of ischemia and keep higher reactivities after 6 hours of ischemia.
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