title: Cytochrome P450-derived arachidonic acid metabolism in the rat kidney: characterization of selective inhibitors.
abstract: We characterized the inhibitory activity of several acetylenic and olefinic compounds on cytochrome P450 (CYP)-derived arachidonic acid omega-hydroxylation and epoxidation using rat renal cortical microsomes and recombinant CYP proteins. Among the acetylenic compounds, 6-(2-propargyloxyphenyl)hexanoic acid (PPOH) and N-methylsulfonyl-6-(2-propargyloxyphenyl)hexanamide were found to be potent and selective inhibitors of microsomal epoxidation with IC50 values of 9 and 13 microM, respectively. On the other hand, 17-octadecynoic acid inhibited both omega-hydroxylation and epoxidation of arachidonic acid with IC50 values of 7 and 5 microM, respectively. The olefinic compounds N-methylsulfonyl-12, 12-dibromododec-11-enamide (DDMS) and 12, 12-dibromododec-11-enoic acid (DBDD) exhibited a high degree of selectivity inhibiting microsomal omega-hydroxylation with an IC50 value of 2 microM, whereas the IC50 values for epoxidation were 60 and 51 microM for DDMS and DBDD, respectively. Studies using recombinant rat CYP4A isoforms showed that PPOH caused a concentration-dependent inhibition of omega-hydroxylation and 11, 12-epoxidation by CYP4A3 or CYP4A2 but had no effect on CYP4A1-catalyzed omega-hydroxylase activity. On the other hand, DDMS inhibited both CYP4A1- and CYP4A3- or CYP4A2-catalyzed arachidonic acid oxidations. Inhibition of microsomal activity by PPOH, but not DDMS, was time- and NADPH-dependent, a result characteristic of a mechanism-based irreversible inhibitor. These studies provide information useful for evaluating the role of the CYP-derived arachidonic acid metabolites in the regulation of renal function and blood pressure.
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Wang
authors.forename: E
authors.initials: E
authors.lastname: Brand-Schieber
authors.forename: B A
authors.initials: BA
authors.lastname: Zand
authors.forename: X
authors.initials: X
authors.lastname: Nguyen
authors.forename: J R
authors.initials: JR
authors.lastname: Falck
authors.forename: N
authors.initials: N
authors.lastname: Balu
authors.forename: M L
authors.initials: ML
authors.lastname: Schwartzman
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004852:Epoxy Compounds / Q000378:metabolism; D006900:Hydroxylation; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008861:Microsomes / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D004852:Epoxy Compounds; D011994:Recombinant Proteins; D016718:Arachidonic Acid; D003577:Cytochrome P-450 Enzyme System