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 systemes, 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.