Effects of hyperoxia and diet on murine tissue levels of vitamin E and polyunsaturated fatty acids

One hundred eighty-six adult female mice were studied to examine the effect of manipulating dietary vitamin E and fractional inspired oxygen concentrations (FiO₂) on tissue levels of vitamin E, total polyunsaturated fatty acids (TPUFA) and conjugated dienes (CD) as an index of lipid peroxidation. Animals were fed custom diets containing either 0, 50 or 150 ppm DL-α-tocopheryl acetate. Once plasma vitamin E levels of mice fell below 0.2 mg/dl (at week 19), all mice were placed in chambers containing either room air (FiO₂≈0.21) or FiO₂>0.95 for the next 72 hr. Dietary manipulation had a major impact on the levels of vitamin E in plasma, lung and perirenal adipose tissues (p<0.0001, p<0.0001 and p<0.005, respectively). Dietary vitamin E deprivation was associated with significant reductions in lung glutathione peroxidase (GPX) activities (p<0.05) and in plasma TPUFA levels (p<0.05). No significant effect attributable to either diet or FiO₂ was observed for liver vitamin E, liver TPUFA or lung TPUFA levels, or for those of CD in any tissue examined. Adipose TPUFA levels were depressed in all dietary groups exposed to FiO₂>0.95, when compared with those of groups exposed to room air. The high FiO₂ exposures also were associated with marked reductions in lung to body weight ratios (p<0.01). These data suggest that dietary vitamin E treatment after long-term feeding can modify vitamin levels in plasma, lung and adipose tissue, and lung GPX activities. Vitamin E levels in liver seemed less responsive to our dietary manipulations in adult female mice, though expressing liver vitamin E levels in terms of TPUFA revealed significant differences between the ratios from 0 and 150 ppm vitamin E groups (p<0.05).