Modulation of procainamide toxicity by selenium-enriched yeast in rats.

Free radical processes are proposed to play a crucial role in the development of procainamide adverse effects. Therefore, selenium, as a potent antioxidant, may modified procainamide toxicity. To test this hypothesis plasma and liver thiobarbituric acid-reacting substances (TBARS), plasma antioxidant activity (AOA), erythrocyte and liver superoxide dismutase (SOD), catalase, as well as selenium-dependent glutathione peroxidase (Se-GPX) were determined in the following four groups of rats: selenium-treated (Se), procainamide-treated (P), procainamide and selenium-treated (P + Se), and control (C). Morphological studies of leukocytes [tested for lupus erythematosus (LE) cells] and liver were also made. Atypical, i.e. enlarged and swollen, leukocytes resulting from procainamide and selenium treatment were observed. These changes were found in four out of five rats in the Se group, eight out of ten in the P group, and in seven out of ten in the P + Se group. LE-like cells were observed in two rats in the P + Se group. A statistically significant decrease in plasma and liver TBARS by 20% and 36%, respectively, increased activity of SOD by 20%, catalase by 48% and Se-GPX by 15% in erythrocytes, and decreased activity of liver SOD by 17% and catalase by 22% were found in the P + Se group as compared to the P group. These results indicated that selenium exerted antioxidant effects on the procainamide-treated rats. However, selenium did not prevent the development of disturbances in leukocyte morphology, on the contrary, it possibly promoted the conversion of leukocytes to LE cells.