title: 3-methylcholanthrene-induced monooxygenase (O-deethylation) activity of human lymphocytes.
abstract: With a direct fluorescence assay, the levels of mixed-function oxidase activity were determined in mitogen-activated human lymphocytes. The O-deethylation of ethoxyresorufin to resorufin was used to quantitate mixed-function oxidase activity. Ethoxyresorufin O-deethylase activity was low to nondetectable in noninduced, mitogen-activated cells, but it was readily detected in 3-methylcholanthrene, mitogen-activated lymphocytes. The activity was: (a) dependent on assay time and number of lymphocytes; (b) dependent on the presence of reduced nicotinamide adenine dinucleotide phosphate; (c) stable to freezing at -80 degrees for at least 2 weeks; (d) reproducibly detected in duplicate samples of blood from one individual when cultured and assayed at the same time; but (e) quite variable in samples of blood from one individual at different times. Since in hepatic and pulmonary tissue of model animal systems ethoxyresorufin is a specific substrate for cytochrome P-448-associated monooxygenases, the use of this chemical could proffer an assay that specifically measures human cytochrome P-448-associated activity.
mesh_terms: D000328:Adult; D001189:Aryl Hydrocarbon Hydroxylases / Q000032:analysis / Q000096:biosynthesis; D001580:Benzopyrenes / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D006899:Mixed Function Oxygenases / Q000032:analysis / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010078:Oxazines / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*
chemical_list: D001580:Benzopyrenes; D003580:Cytochromes; D010078:Oxazines; D009243:NAD; D008748:Methylcholanthrene; C007649:ethoxyresorufin; C014180:resorufin; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D001189:Aryl Hydrocarbon Hydroxylases