Antioxidant vitamin levels and glutathione peroxidase activity during ischemia/reperfusion in myocardial infarction

The consequences of increased oxidative stress, measured as the level of ma londialdehyde (MDA) during ischemia/reperfusion, were studied in 48 patient s in the acute phase of myocardial infarction (AMI) and a control group (21 blood donors). The serum levels of alpha -tocopherol and beta -carotene we re followed. Immediately after the treatment onset the level of alpha -toco pherol started to decrease, reaching a plateau after 24 h. The consumption of beta -carotene was delayed by 90 min. Steady decline was detected during the whole time interval studied (48 h). Glutathione peroxidase (GPx) activ ity, as a representative of antioxidant enzymes, was estimated in whole blo od. The influx of oxygenated blood was accompanied by a stimulation of GPx activity, which reached its maximum at the time of completed reperfusion. W hen comparing the AMI patients with the control group, the levels of MDA we re found significantly increased, which indicates that oxidative stress is already increased during ischemia. Lower antioxidant levels found in the pa tients might either already be the result of vitamin consumption during isc hemia or be a manifestation of their susceptibility to AMI. Monitored consu mption of alpha -tocopherol and beta -carotene during reperfusion indicated that in the case of patients, whose level of antioxidant vitamins is below the threshold limit, a further substantial decrease of antioxidant vitamin s during reperfusion could enhance the oxidative damage of the myocardium.