Increased glutathione in cultured hepatocytes associated with induction of cytochrome P-450

Cellular glutathione concentrations in primary cultures of chick embryo hepatocytes were 15.3 ± 5.3 nmoles/mg protein (mean ± S.D.) and remained stable for up to 3 days in culture. The presence of insulin was not essential for the maintenance of glutathione concentrations. Induction of cytochrome P-450 by phenobarbital-like inducers (2-propyl-2-isopropylacetamide, 2-allyl-2-isopropylacetamide, and 2,4,5,2′,4′,5′-hexabromobiphenyl) was accompanied by 2- to 3-fold increases in glutathione concentrations and by increased glucuronidation of phenol red. The 3-methylcholanthrene-like inducers of cytochrome P-450 (β-naphthoflavone and 3,4,3′,4′-tetrachlorobiphenyl) did not have these effects. Glutathione was rapidly depleted to 15–30% of control levels in hepatocytes treated with buthionine sulfoximine, an inhibitor of γ-glutamylcysteine synthase. No toxicity was observed with glutathione depletion. Glutathione depletion did not affect the ability of 2-propyl-2-isopropylacetamide to induce cytochrome P-450, glucuronidation of phenol red, or δ-aminolevulinate synthase.