The Effects of Cytochrome P450 Inhibition On Glutathione Conjugation of Perchloroethylene and Trichloroethylene in Rat Renal Cortical Cells and Hepatocytes

Abstract

Trichloroethylene (TRI) and Perchloroethylene (PER) are environmental contaminants whose ingestion, inhalation or absorption can lead to species-, strain-, and gender-specific toxicity and carcinogenicity through bioactivation, occurring by either glutathione (GSH) conjugation or cytochrome P450 oxidation. Cytochrome P450 oxidation is thought to affect the lung, liver, and other extra-renal tissue, whereas GSH conjugation is thought to lead to nephrotoxicity and nephrocarcinogenicity, through still undetermined mechanisms. To better characterize their metabolism, the effects of cytochrome P450 inhibitors on GSH conjugation ofTRI and PER in freshly isolated rat renal cortical cells and hepatocytes were studied. , Suspensions of cells were incubated with either TRI or PER and one of three , cytochrome P450 inhibitors: SKF 525A, metyrapone, or diethyldithiocarbamic acid (DITC). These incubations were arrested at 15 min intervals with 70% perchloric acid and reactive GSH conjugation metabolites of TRI and PER, S- (1,2- dichlorovinyl)glutathione (DCVG) and S- (1,2,2-trichlorovinyl)glutathione (TCVG) respectively, were measured by high-performance liquid chromatography. Amounts of DCVG/TCVG were thought to be indicative of the amounts of TRIlPER metabolized by the GSH conjugation pathway; however, these experiments were inconclusive. Another set of experiments measured cell death in cell suspensions incubated with PER and either diethyl maleate or buthionine sulfoximine (BSO) (inhibitors of the GSH conjugation pathway) by % release of lactate dehydrogenase (LDH). Spectrophotometry was used to determine cell death at 1 hour intervals, with inconclusive results.