Selective antioxidant enzymes during ischemia/reperfusion in myocardial infarction

The study of ischemia/reperfusion injury included 25 patients in the acute phase of myocardial infarction (19 perfused, 6 remained non-reperfused as e valuated according to the time course of creatine kinase and CK-MB isoenzym e activity) and a control group (21 blood donors). Plasma level of malondia ldehyde was followed as a marker of oxidative stress. Shortly after reperfu sion (within 90 min), a transient increase of malondialdehyde concentration was detected. The return to the baseline level was achieved 6 h after the onset of therapy. The activity of a free radical scavenger enzyme, plasma g lutathione peroxidase (GPx), reached its maximum 90 min after the onset of treatment and returned to the initial value after 18 h. The specificity of the GPx response was confirmed by comparing with both non-reperfused patien ts and the control group, where no significant increase was detected. The e rythrocyte Cu,Zn-superoxide dismutase (SOD) did not exhibit significant cha nges during the interval studied in perfused patients, probably due to the stability of erythrocyte metabolism. In non-reperfused patients, a decrease of SOD was found during prolonged hypoxia. These results help to elucidate the mechanisms of fast activation of plasma antioxidant system during the reperfusion after myocardial infarction.