Protective role of ubiquinone in vitamin E and selenium-deficient plasma membranes.

We have studied the effects of dietary depletion of vitamin E and selenium on endogenous ubiquinone-dependent antioxidant system. Deficiency induced an increase in both coenzyme Q9 and Q10 in liver tissue, reaching a maximum between 4 and 7 weeks of deficient diet consumption. Cytochrome b5 reductase polypeptide was also enriched in membranes after 5 weeks of deficient diet consumption. Substantial DT-diaphorase activity was found in deficient, but not in control plasma membranes. Deficient membranes were very sensitive to lipid peroxidation, although a great protection was observed after incubation with NAD(P)H. Our results show that liver cells can boost endogenous ubiquinone-dependent protective mechanisms in response to deficiency in vitamin E and selenium.