NONINVOLVEMENT OF CYP2E1 IN THE (OMEGA-1)-HYDROXYLATION OF FATTY-ACIDS IN RAT-KIDNEY MICROSOMES

Pyrazole, acetone, and ethanol are known to induce cytochrome P450 2E1 (CYP2E1) and fatty acid (omega-1)-hydroxylation in rat liver microsom es. However, the nature of the P450 enzyme involved in this (omega-1) hydroxylation has not been clearly established in extrahepatic tissues such as kidney. Four enzymatic activities (hydroxylations of chlorzox azone, dr-nitrophenol, and two fatty acids) were assayed in kidney mic rosomal preparations of rats treated with CYP2E1 inducers. Per os trea tment resulted in large increases (threefold to fivefold) in the chlor zoxazone and 4-nitrophenol hydroxylations, and up to a ninefold increa se when ethanol was administered by inhalation. However, neither the o mega-hydroxylation nor the (omega-1)-hydroxylation of fatty acids was modified. Immunoinhibition specific to CYP2E1 did not significantly de crease the omega- and (omega-1) lauric acid hydroxylations, while the polyclonal anti-CYP4A1 antibody inhibited in part both the omega- and (omega-1)-hydroxylations. Chemical inhibitions using either CYP2E1 com petitive inhibitors (such as chlorzoxazone, DMSO, and ethanol) or P450 mechanism-based inhibitors (such as diethyldithiocarbamate and 17-oct adecynoic acid) led to a partial inhibition of the hydroxylations. All these results suggest that fatty acid (omega-1) hydroxylation, a high ly specific probe for CYP2E1 in rat and human liver microsomes, is not mediated by CYP2E1 in rat kidney microsomes. In contrast to liver, wh ere two different P450 enzymes are involved in fatty acid omega- and ( omega-1)-hydroxylations, the same P450 enzyme, mainly a member of the CYP4A family, was involved in both hydroxylations in rat renal microso mes. (C) 1997 Elsevier Science Inc.