3-METHYLCHOLANTHRENE-INDUCED MONOOXYGENASE (O-DEETHYLATION) ACTIVITY OF HUMAN LYMPHOCYTES

  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (2) , 460-463
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 dependent on assay time and number of lymphocytes; dependent on the presence of NADPH; stable to freezing at -80.degree. C for at least 2 wk; reproducibly detected in duplicate samples of blood from 1 individual when cultured and assayed at the same time; but quite variable in samples of blood from 1 individual at different times. Since in hepatic and pulmonary tissue of model mouse 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. [A correlation exists between bronchogenic cancer susceptibility and enzyme inducibility.].

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