EFFECTS OF DIETARY ZINC AND CADMIUM ON TISSUE SELENIUM CONCENTRATION AND GLUTATHIONE-PEROXIDASE ACTIVITY IN RATS FED DL-SELENOMETHIONINE OR SODIUM SELENITE

The effects of dietary zinc (Zn) and cadmium (Cd) on tissue selenium (Se) concentration and glutathione peroxidase (GSH-Px) activity were studied in weanling male Wistar rats. One group of rats was fed a purified diet based on casein and sucrose, and the other rats used in a 2 x 2 x 2 factorial arrangement of treatment were fed this diet supplemented with 0.1 mg Se/kg, either as DL-selenomethionine or sodium selenite and plus 100 mg Zn/kg as zinc sulfate or 5 mg Cd/kg as cadmium chloride or both for 4 weeks. Se concentrations in plasma, erythrocytes, muscle, heart, and liver were significantly elevated by Zn. Cd significantly decreased Se concentration in muscle. Addition of Zn to the diets markedly increased (p < 0.001) hepatic GSH-Px activity. However, Cd in the diets produced a significant increase (p < 0.001) in erythrocyte GSH-Px activity. These results indicate that Zn level of marginal deficiency (8.6 mg/kg diet) can decrease Se availability and a small excess of Zn increases Se availability for hepatic GSH-Px activity.