title: Effect of xenobiotics on monooxygenase activities in cultured human hepatocytes.
abstract: The activity of human cytochrome P450 monooxygenases, aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase can be increased by 3-methylcholanthrene, phenobarbital and ethanol in human hepatocytes maintained in primary culture. Total cytochrome P450 content increased two-fold after 48 hr of incubation with methylcholanthrene or phenobarbital and 1.5-fold after incubation with ethanol. The three chemicals elicited different effects on cytochrome P450 dependent activities. Addition of 3-methylcholanthrene caused a time- and concentration-dependent increase in both monooxygenase activities, aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase, while phenobarbital and ethanol increased 7-ethoxycoumarin O-deethylase activity but had no effect on aryl hydrocarbon hydroxylase. Dexamethasone per se had little or no effect on either monooxygenase activities, but potentiated the effect of the three chemicals on 7-ethoxycoumarin O-deethylase.
authors.affiliation: Unidad de Hepatologia Experimental, Hospital La Fe, Valencia, Spain.
authors.forename: M T
authors.initials: MT
authors.lastname: Donato
authors.forename: M J
authors.initials: MJ
authors.lastname: Gómez-Lechón
authors.forename: J V
authors.initials: JV
authors.lastname: Castell
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase / Q000096:biosynthesis; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis; D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D003907:Dexamethasone / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology; D005260:Female; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008875:Middle Aged; D010105:Oxygenases / Q000096:biosynthesis*; D010634:Phenobarbital / Q000494:pharmacology; D015262:Xenobiotics / Q000494:pharmacology*
chemical_list: D015262:Xenobiotics; D000431:Ethanol; D008748:Methylcholanthrene; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D001189:Aryl Hydrocarbon Hydroxylases; D010634:Phenobarbital