MEASUREMENT OF CYTOCHROME-P450 2E1 ACTIVITY IN RAT TRACHEOBRONCHIAL AIRWAYS USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

Cytochrome P450 2E1 catalyzes the metabolic activation of nitrosamines and haloalkenes to carcino genic and cytotoxic derivatives; however, the regulation of this P450 isozyme is not well understood. Hydroxylat ion of p-nitrophenol to p-nitrocatechol has been used as a marker of C YP2E1 activity, but currently available methodologies are not sufficie ntly sensitive to allow measurements in small tissue samples or in tis sues with low activity such as lung, We describe here a method for mea suring p-nitrocatechol formation using HPLC with electrochemical detec tion which is rapid and specific. It has a level of sensitivity (pmol) sufficient to monitor CYP2E1 activities in incubations containing as little as 10 mu g microsomal protein prepared from airway subcompartme nts of the lung, a tissue with low and varying CYP2E1 activities among different parts of the airways. (C) 1997 Academic Press.