A MICROASSAY FOR THE DETECTION OF LOW-LEVELS OF CYTOCHROME-P450 O-DEETHYLATION ACTIVITIES WITH ALKOXYRESORUFIN SUBSTRATES

A microfluorometric method for the detection of low levels of cytochro me P450 was developed to increase the sensitivity of the assay, since a low level of CYP450 associated enzymatic activities was expected in human placenta tissues and small samples of placenta (similar to 10 g) could be easily collected, stored and processed, The dual fluorescenc e assay of Kennedy et al, [1], which was developed to simultaneously q uantitate microsomal proteins and ethoxyresorufin-O-deethylase (EROD) activity was adapted for 96 wells microtiter plates. Placental microso mes samples were analyzed, For samples obtained from non-smoking mothe rs from the general southern Quebec population, results ranged from le ss than 1-3.3 pmol/mg protein min. Samples collected from smoking moth ers showed activity levels ranging from 30-69 pmol/mg protein min. The se results showed the suitability of the microassay for measuring low level of CYP450 activity in tissues such as placenta.