Some metabolic interrelationships between toxic levels of cadmium and nontoxic levels of selenium fed to rats.

Male rats were fed vitamin E-adequate, Torula yeast-based diets for 30 days to assess the influence of dietary selenium (0, 0.1, or 1.0 ppm) on the toxicity of dietary cadmium (0, 30, or 60 ppm). At all selenium levels, increased cadmium intake depressed feed consumption, reduced feed efficiency and lowered body weight gain. In liver, concentrations of cadmium and zinc increased, and iron concentration decreased with increased intake of cadmium. Dietary selenium did not affect concentrations of cadmium, zinc, iron or copper in liver. Blood hemoglobin level declined and relative heart weight (g/100 g body wt) increased with increased intake of cadmium. Increased selenium intake partially alleviated the cadmium-induced depression in blood hemoglobin levels in rats fed diets that contained 30 ppm cadmium, and partially ameliorated the cadmium-induced increase in heart size in rats fed either 30 or 60 ppm cadmium. Hepatic and renal glutathione peroxidase (GSH-Px) activity increased with increased selenium intake. Increased cadmium intake did not affect renal GSH-Px activity. Hepatic GSH-Px activity in rats fed diets that contained 0.1 ppm selenium decreased with increased cadmium intake; however, hepatic GSH-Px activity was not affected by dietary cadmium in rats fed diets that contained 1.0 ppm selenium. Interactions between nontoxic levels of dietary selenium and relatively high levels of dietary cadmium apparently resulted in an antagonism of selenium metabolism by cadmium in some systems, and partial amelioration of cadmium toxicity by selenium in other systems