Effects of glutathione on the alpha-tocopherol-dependent inhibition of nuclear lipid peroxidation.

Endogenous alpha-tocopherol levels in isolated rat liver nuclei were determined to be 0.045 mol% (mol alpha-tocopherol per mol phospholipid x 100). This value corresponds to 970 polyunsaturated fatty acid (PUFA) moieties to one molecule of alpha-tocopherol in the nuclear membrane. Isolated nuclei, when incubated with various concentrations of exogenous alpha-tocopherol, took up only a small percent of initial levels of alpha-tocopherol present in the incubation media. Exogenous alpha-tocopherol, when incorporated in isolated nuclei above a threshold value of 0.085 mol%, effectively inhibited NADPH-induced lipid peroxidation. The addition of 1 mM glutathione lowered the threshold levels of alpha-tocopherol needed to inhibit lipid peroxidation to about 0.040 mol%. We suggest the data indicate a glutathione-dependent enhancement of the ability of alpha-tocopherol to inhibit nuclear lipid peroxidation.