[Studies on reperfusion injury of rat hindlimb]

Using the isolated perfused rat hindlimb, we have examined the effect of superoxide dismutase (SOD) for protection against reperfusion injury. In vivo experiments, after the isolation of the rats hindlimb, we clamped their aorta and vena cava, and divided the rats into two groups. After occluding the aorta and vena cava of each rat for two hours, one group was administered physiological saline 0.4 ml/100 g, and the other SOD of 15,000 U/100 g. Their blood was sampled 5 and 30 minutes after the clamps were released. In the presence of SOD, the release of the creatine phosphokinase (CPK) was suppressed, but this was not significant. In vitro experiments, on the other hand, the isolated perfused rat hindlimb was prepared with Krebs-Henseleit bicarbonate buffer as a perfusate. Similar experiments in vivo were performed; one group was the control, the other was administered SOD 30,000 U/L in the perfusate. The peak of LACTATE and CPK in the effluent was clearly dissociated for 30 min after reperfusion of oxygen. This result showed that our experimental model was suited to the study of ischemia reperfusion injury, as differentiated from simple anoxia. The CPK release into the effluent was successfully suppressed when SOD was present (p less than 0.05). Using a spin trapping ESR technique, we detected DMPO-carbon centered adduct in the effluent. The adduct of the radical had 6 lines and was assigned as the lipid radical. In summary, this model is very useful to study metabolism of skeletal muscle. And we are convinced of that lipid peroxidation is involved in reperfusion-induced cell damage, and then SOD is effective to the protection against reperfusion injury.