Increased plasma glutathione peroxidase activity in patients with acute myocardial infarction

Aim of the study was to determine the concentration of selenium (Se) and the activity of glutathione peroxidase (GSH-Px) in patients with acute myocardial infarction (AMI) and to observe the behavior of these parameters during thrombolysis therapy.

The study comprised two groups of AMI patients and a control group. The first group consisted of 49 patients from whom blood samples were taken after admission to the intensive care unit and subsequently after 3, 7, 14 and 30 days of hospitalization. In the second group of patients (n = 18) blood was taken for measuring only the GSH-Px activity in plasma. In this group blood samples were collected after admission to the hospital, 6, 12, 24, 48 hours, 3, 7, 14 and 30 days later. Control group comprised of 58 healthy subjects. Se levels in whole blood and plasma were measured spectrofluorometrically with 2,3-diaminonaphthalene as a complexing reagent. GSH-Px activity in red cells and plasma was measured spectrofluorometrically with t-butyl hydroperoxide as substrate.

In the first group of patients Se concentrations in whole blood and plasma as well as GSH-Px activities in red cells and plasma did not differ significantly from healthy subjects. Both Se levels and GSH-Px activities were stable during the entire period of the study. In the second group of patients, however, plasma GSH-Px activity increased after admission and reached the highest value after 48 hours. This activity was significantly higher compared to healthy subjects (p < 0.004) and to the mean initial activity of this group (p < 0.02). In the later period the activity decreased to the values of healthy subjects.

We suggest that the increased activity of GSH-Px in plasma of AMI patients is the response of the organism to the increased levels of reactive oxygen species produced during reperfusion and thrombolysis.