Drug and fatty acid hydroxylation by solubilized human liver microsomal cytochrome P-450-phospholipid requirement.

sideration in the literature [13]. As a result, the findings obtained in this investigation may be applicable to the study of PMA in other cell systems. According to Augustinsson [S], each esterase type exists in multiple forms and each animal species has its own typical spectrum of esterases in plasma and tissues [14]. In the presence of marked variations in location, form and activity, one might expect significant differences in the effects of drugs which stimulate or inhibit these enzymes in different species. If the pharmacological action of a drug is dependent on ester groups, then the presence of esterases in all affected cells and tissues would have to be considered in evaluating the influence of the agent. PMA has been used extensively as a co-carcinogen in animal studies [13]. It would be of interest to determine if endogenous esterases or the concomitant use of esterase inhibitors would influence the tumor-promoting action of PMA.