Effects of 1,1-dichloroethene and of some of its metabolites on the functional viability of mouse hepatocytes.
1,1-Dichloroethene (DCE) is hepatotoxic in rodents, and the expression of its toxicity involves probably its metabolism. In this study the role of DCE metabolites in the generation of the hepatotoxic lesion was investigated. Hepatocytes from male BALB/c mice in suspension were used as the experimental model. Cells were incubated with DCE for up to 5 hr and cellular viability was assessed by measurement of the release of lactate dehydrogenase into the medium and by alterations in the reduction of the dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. After incubation for 3 hr DCE at 0.5 mM caused maximal toxicity, whereas at 0.1 mM DCE was only marginally toxic. Cytotoxicity was exacerbated by pretreatment of mice with buthionine sulfoximine (1.6 g/kg), an inhibitor of glutathione biosynthesis, given 4 hr prior to hepatocyte isolation. Inclusion of N-acetylcysteine (10 mM) into the incubate protected cells against DCE-induced cytotoxicity. Coincubation with octylamine (0.5 mM), an inhibitor of cytochrome P450, abolished the cytotoxic potential of 0.5 mM DCE during incubation for 3 hr. DCE toxicity was increased in hepatocytes from mice which had received ethanol or acetone in their drinking water, both of which induce levels of the hepatic cytochrome P450 isozyme P450 2E1. Incubation of cells with the P450 2E1 inhibitors N,N-dimethylformamide (10 mM) or diethyldithiocarbamate (100 microM) protected liver cells against the detrimental effect of DCE. Pretreatment of animals with phenobarbital, which induces the P450 2B subfamily, or 3-methylcholanthrene, which induces P450 1A1, did not affect the degree of hepatocytotoxicity elicited DCE.(ABSTRACT TRUNCATED AT 250 WORDS)
Kainz
A
A
Pharmaceutical Sciences Institute, Aston University, Aston Triangle, Birmingham, United Kingdom.
Cross
H
H
Freeman
S
S
Gescher
A
A
Chipman
J K
JK
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004000:Dichloroethylenes / Q000378:metabolism / Q000633:toxicity*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D013438:Sulfhydryl Compounds / Q000378:metabolism
D004000:Dichloroethylenes; D007527:Isoenzymes; D013438:Sulfhydryl Compounds; C029297:vinylidene chloride; D003577:Cytochrome P-450 Enzyme System