The regulation of prostaglandin and arachidonoyl-CoA formation from arachidonic acid in rabbit kidney medulla microsomes by palmitoyl-CoA.
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 palmitic acid (PA) and palmitoyl-CoA (PA-CoA) 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 [14C]-AA in 0.1 M-Tris/HCl buffer (pH 8.0) containing cofactors of COX (reduced glutathione and hydroquinone) and cofactors of ACS (ATP, MgCl2 and CoA). After incubation, PG (as total PGs), AA-CoA and residual AA were separated by selective extraction using petroleum ether and ethyl acetate. PA (10-100 microM) had no effect on the PG and AA-CoA formation from either 60 or 5 microM AA. PA-CoA (10-100 microM) was without effect on the PG and AA-CoA formation from 60 microM AA, whereas it markedly decreased the PG formation (6-40%) and increased the AA-CoA formation (1.1-2.3-fold) from 5 microM AA, showing that the effects of PA-CoA on the PG and AA-CoA formation change depending on the AA concentration. These results suggest that PA-CoA, but not PA, may regulate the PG and AA-CoA formation at low substrate concentrations (close to the physiological concentration of AA), and that this in-vitro method using 5 microM AA may be useful for clarifying the homeostatic control of the metabolic fate of AA into these two enzymatic pathways.
Sakuma
S
S
Department of Hygienic Chemistry, Osaka University of Pharmaceutical Sciences, Takatsuki, Japan. sakuma@oysun01.oups.ac.jp
Fujimoto
Y
Y
Katoh
Y
Y
Kitao
A
A
Fujita
T
T
D000214:Acyl Coenzyme A / Q000096:biosynthesis*; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D007679:Kidney Medulla / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008861:Microsomes / Q000187:drug effects* / Q000378:metabolism; D019308:Palmitic Acid / Q000494:pharmacology; D010171:Palmitoyl Coenzyme A / Q000494:pharmacology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011453:Prostaglandins / Q000096:biosynthesis*; D011817:Rabbits
D000214:Acyl Coenzyme A; D001095:Arachidonic Acids; D016861:Cyclooxygenase Inhibitors; D011453:Prostaglandins; C026563:arachidonyl-coenzyme A; D010171:Palmitoyl Coenzyme A; D019308:Palmitic Acid; D011451:Prostaglandin-Endoperoxide Synthases; D007213:Indomethacin