Adaptive responses to fatty acids are mediated by the regulated expression of cytochromes P450.

treatment with PLA,. At this stage it is impossible to say whether the presence of such large amounts of lysophospholipids has a role in isoenzyme inactivation. Nevertheless it can be hypothesized that each P450 isoenzyme responds differently to changes in membrane NEFA content and composition. This situation might facilitate the selective modulation of P450 isoenzyme activity depending on the overall requirements of the cell, tissue or body. For example, in the present study, the presence of NEFAs in the environment of the 3A family of isoenzymes seems to have a suppressing effect on the 6/%hydroxylation of testosterone. Consequently, the clearance of NEFAs from the membrane (perhaps in response to hormonal signals), would lead to enhanced testosterone hydroxylation, whereas the sequestration of excess dietary NEFAs in the membrane could lead to a further suppression of isoenzyme activity.