Early reperfusion after myocardial infarction improves survival rate and is thought to preserve myocardial function, but the reperfusion of ischemic tissue may release oxygen free radicals, which could adversely affect left ventricular function and diminish the beneficial effects of reperfusion. Measurements related to free radical scavenging (plasma and erythrocyte enzyme systems, which are involved in free radical control, alpha-tocopherol, selenium, and manganese superoxide dismutase) may be indirect markers of free radical production. We evaluated 10 patients undergoing coronary angioplasty within 4 hours of myocardial infarction to measure the impact of abrupt reperfusion on free radical scavenger-related indexes. Pulmonary artery samples were taken before, immediately after, and 3 hours after angioplasty. During reperfusion, significant reductions occurred in alpha-tocopherol (1.1 +/- 0.3 mg/dl before, 0.9 +/- 0.2 mg/dl immediately after [p = 0.03], and 0.8 +/- 0.2 mg/dl 3 hours after percutaneous transluminal coronary angioplasty [p = 0.02]), and selenium levels (13.7 +/- 2.4 micrograms/dl before, 12.9 +/- 2.4 micrograms/dl immediately after, and 10.2 +/- 3.0 micrograms/dl 3 hours after angioplasty [p = 0.0006]). Erythrocyte markers (glutathione peroxidase and superoxide dismutase) were not altered by reperfusion, possibly reflecting the relatively long half-life of the erythrocyte. The erythrocyte glutathione peroxidase value before reperfusion in patients (30.8 +/- 5.1 IU/gm of hemoglobin) was lower than in a control group (36.1 +/- 6.5 IU/gm of hemoglobin; p = 0.01). Thus the decrease in plasma alpha-tocopherol and selenium after reperfusion in this group of patients may reflect a general alteration in plasma free radical scavenger levels, suggesting consumption of plasma free radical scavengers with reperfusion after acute myocardial infarction.