Mechanism-based inactivation of cytochrome P450 1A1 by N-aralkyl-1-aminobenzotriazoles in guinea pig kidney in vivo and in vitro: minimal effects on metabolism of arachidonic acid by renal P450-dependent monooxygenases.
Guinea pig renal microsomes convert arachidonic acid to two classes of P450-dependent metabolites, epoxyeicosatrienoic acids (EET), and 16- through 20-hydroxyeicosatetraenoic acids [(16-20)-OH-AA)]. The rate of formation of these metabolites was not altered by beta-naphthoflavone induction, which increased P450 1A1-dependent 7-ethoxyresorufin O-deethylation activity approximately 100-fold. alpha-Naphthoflavone, which inhibits renal P450 1A1 in vitro, did not inhibit the formation of these metabolites in microsomes from induced animals. In induced animals, N-benzyl-1-aminobenzotriazole and N-alpha-methylbenzyl-1-aminobenzotriazole, administered i.v., inhibited microsomal 7-ethoxyresorufin O-deethylation activity by approximately 50% without inhibiting the formation of either class of arachidonic acid metabolites. In vitro these mechanism-based inhibitors inactivated 1A1 by > 90% without inhibiting EET or (16-20)-OH-AA formation. These data show that P450 1A1 does not bioactivate arachidonic acid to either (16-20)-OH-AA or EET in guinea pig kidney, and that N-benzyl-1-aminobenzotriazole and N-alpha-methylbenzyl-1-aminobenzotriazole selectively inactivate P450 1A1 in comparison to the P450 isozyme(s) that metabolize arachidonic acid in the kidney. In guinea pig liver beta-naphthoflavone treatment, which induces P450 1A1 and 1A2, increased the rate of the formation of (16-20)-OH-AA and EET and in vitro alpha-naphthoflavone inhibited the formation of these metabolites in induced hepatic microsomes by approximately 50 and approximately 35%, respectively. These data demonstrate that a beta-naphthoflavone-inducible isozyme, most likely 1A2, converts arachidonic acid to both (16-20)-OH-AA and EET in guinea pig liver.
Knickle
L C
LC
Department of Pharmacology and Toxicology, University of Western Ontario, London, Canada.
Webb
C D
CD
House
A A
AA
Bend
J R
JR
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001571:Benzoflavones / Q000494:pharmacology; D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D019363:Cytochrome P-450 CYP1A1; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000187:drug effects* / Q000378:metabolism*; D004789:Enzyme Activation; D006168:Guinea Pigs; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D010105:Oxygenases / Q000187:drug effects* / Q000378:metabolism*; D014230:Triazoles / Q000494:pharmacology*; D019324:beta-Naphthoflavone
D001571:Benzoflavones; D002250:Carbon Radioisotopes; D065607:Cytochrome P-450 Enzyme Inhibitors; D014230:Triazoles; C067013:N-benzyl-1-aminobenzotriazole; C059849:alpha-methylbenzylaminobenzotriazole; C033020:1-aminobenzotriazole; D016718:Arachidonic Acid; C011512:alpha-naphthoflavone; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D010105:Oxygenases; D019363:Cytochrome P-450 CYP1A1