title: The regulation of formation of prostaglandins and arachidonoyl-CoA from arachidonic acid in rabbit kidney medulla microsomes by linoleic acid hydroperoxide.
abstract: Under physiological conditions, small amounts of free arachidonic acid (AA) are released from membrane phospholipids, and cyclooxygenase (COX) and acyl-CoA synthetase (ACS) competitively act on this fatty acid to form prostaglandins (PGs) and arachidonoyl-CoA (AA-CoA). In the present study, we investigated the effects of linoleic acid (LA) and 13-hydroperoxyoctadecadienoic acid (13-HPODE) on the PG and AA-CoA formation from high and low concentrations of AA (60 and 5 microM) in rabbit kidney medulla microsomes. The kidney medulla microsomes were incubated with 60 or 5 microM [(14)C]-AA in 0.1M Tris-HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl(2) and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. LA (10-50 microM) reduced only PG formation from both 60 and 5 microM AA. 13-HPODE (10-50 microM) also reduced PG formation from 60 and 5 microM AA, but the inhibitory potency was much stronger than that by LA. Furthermore, 13-HPODE had the potential to increase the AA-CoA formation with a decrease in the PG formation from 5 microM AA. These results suggest that 13-HPODE, but not LA, may shift AA away from COX pathway into ACS pathway under low substrate concentration (near physiological concentration of AA).
authors.affiliation: Laboratory of Physiological Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. sakuma@gly.oups.ac.jp
authors.forename: Satoru
authors.initials: S
authors.lastname: Sakuma
authors.forename: Kumiko
authors.initials: K
authors.lastname: Usa
authors.forename: Yohko
authors.initials: Y
authors.lastname: Fujimoto
mesh_terms: D000214:Acyl Coenzyme A / Q000096:biosynthesis*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D007679:Kidney Medulla / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008041:Linoleic Acids / Q000378:metabolism / Q000494:pharmacology*; D008054:Lipid Peroxides / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D008861:Microsomes / Q000378:metabolism; D011453:Prostaglandins / Q000096:biosynthesis*; D011817:Rabbits
chemical_list: D000214:Acyl Coenzyme A; D008041:Linoleic Acids; D008054:Lipid Peroxides; D011453:Prostaglandins; C026563:arachidonyl-coenzyme A; C038649:13-hydroperoxy-9,11-octadecadienoic acid; D016718:Arachidonic Acid