Enhanced lung toxicity of O₂ in selenium deficient rats

To test the hypothesis that glutathione (GSH) peroxidase is an important component of the lung's anti-oxidant defense systems, O₂ toxicity was studied in selenium (Se)-deficient rats. Chronic respiratory disease free rats fed a Se-deficient diet or a diet supplemented with Se for 40 days after weaning were exposed to 80% O₂ at atmospheric pressures for 3 days. Activities of GSH peroxidase in lungs of Se-deficient rats were markedly lower than corresponding activities in rats supplemented with 0.5 or 2.0 ppm Se. With O₂ exposure, 35% of the rats fed the Se-deficient regimen died, whereas all rats fed Se-supplemented diets survived. Lungs from surviving Se-deficient rats exposed to O₂ were edematous. The data suggest that the toxic effects of O₂ are enhanced in Se-deficient rats and that nutritional factors contribute to lung susceptibility to oxidant-induced damage.