Induction of xenobiotic metabolism in rat liver by chlorinated biphenyl ether isomers.

Chlorinated diphenyl ether isomers were administered to rats at doses of 10 mumols/kg/day po for 3 days. Decachlorodiphenyl ether caused increases in EPN detoxification, NADPH cytochrome c reductase and cytochrome P-450 but did not alter aryl hydrocarbon hydroxylase (AHH). It caused a shift in P450 absorption to 448 nm. 2,4,5,2',4'-Pentachlorodiphenyl ether increased EPN detoxification and cytochrome P-450. 2,4,5,3',4'-Pentachlorodiphenyl ether increased AHH and cytochrome P-450 and caused a shift in the absorption maximum to 448 nm. 3,4,2',4'-Tetrachlorodiphenyl ether induced AHH. 2,4'-Dichlorodiphenyl ether, 4,4'-dichlorodiphenyl ether, 2,4,2'-trichlorodiphenyl ether, 2,4,4'-trichlorodiphenyl ether, 3,4,2'-trichlorodiphenyl ether and 3,4,2',4'-tetrachlorodiphenyl ether did not alter any of these parameters. The position and degree of chlorination are important in determining the extent of induction and pathways induced.