Long-Term NO₂ Exposure of Mice in the Presence and Absence of Vitamin E. II. Effect of Glutathione Peroxidase

Abstract

One hundred and twenty female mice fed diets containing various levels of vitamin E were continuously exposed to 0.5 ppm, 1.0 ppm nitrogen dioxide (NO₂), and filtered air for 17 months. Blood, lung, and liver tissues were assayed for glutathione peroxidase (GSH-peroxidase) activity. Exposure to 0.5 ppm NO₂ did not affect blood and lung GSH peroxidase activity; 1.0 ppm NO₂ exposure, however, caused suppression of the enzyme. A combination of vitamin E deficiency and 1.0 ppm NO₂ exposure resulted in the lowest GSH-peroxidase activities in the blood and lung. High levels of vitamin E in the diet resulted in elevated GSH-peroxidase in the blood and lung. Liver GSH-peroxidase activity was unaffected by either dietary vitamin E or NO₂ exposure. No inverse relationship was found between GSH-peroxidase levels and concentrations of organic solvent soluble lipofuscin pigments present in tissues.