dinoprost and 1-benzylimidazole

Production of eicosanoids by deendothelialized aorta in response to continuous infusions of arachidonic acid and platelet suspensions was determined in a rabbit aorta perfusion model. 6-keto-PGF1 alpha production was stimulated by AA infusion in a dose-related manner. Infusion of AA at 4 micrograms/ml/min led to an initial production rate of 0.64 +/- 0.29 ng/min which gradually increased to 0.93 +/- 0.11 ng/min at the 20th min of infusion. When the concentration of AA infusion was increased to 10 micrograms/ml/min, 6-keto-PGF1 alpha production increased to 1.14 +/- 0.86 ng/min initially but declined with time. PGE2 production in response to AA 10 micrograms/min/ml was steady at around 5 ng/min while PGF2 alpha and TXB2 production were only slightly above the control. Perfusion of rabbit washed platelet suspensions at a rate of 3 X 10(8) plt/ml/min raised 6KPGF1 alpha production. The production was further increased when platelets were pretreated with 1-benzylimidazole (5 mM), along with a concurrent reduction in TXB2 release. Pretreatment of platelets with aspirin, on the other hand, abolished the increase in 6KPGF1 alpha production. Our data indicated that the vascular smooth muscle cells can efficiently utilize PGH2 produced by platelets to synthesize PGI2.

Topics: Animals; Aorta; Blood Platelets; Blood Vessels; Dinoprost; Dinoprostone; Dose-Response Relationship, Drug; Eicosanoic Acids; Endothelium; Epoprostenol; Imidazoles; In Vitro Techniques; Perfusion; Platelet Transfusion; Prostaglandin Endoperoxides, Synthetic; Prostaglandin H2; Prostaglandins E; Prostaglandins F; Prostaglandins H; Rabbits; Thromboxane B2

Murine macrophage-like cell lines, J774.2, P388D1, RAW264.7 and PU-5-1R, were incubated with exogenous arachidonic acid (AA). The major metabolites were identified by comigration with known standards in TLC and HPLC and by characteristic behavior following reduction. During a 30 min incubation J774.2 cells metabolized exogenous 14C-AA (10 microM) to PGE2 (14.8%), 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) (13.0%), thromboxane B2 (TXB2) (7.4%), PGD2 (4.4%) and PGF2 alpha (3.0%). The remainder was incorporated into phospholipids (39.0%), triglycerides (6.1%), and as yet unidentified metabolites (8.2%). No PGF1 alpha was found. Metabolism of exogenous AA was rapid, being less than 90% completed at 3.5 min. Metabolism of exogenous AA is not increased by the simultaneous addition of macrophage stimuli including the cation ionophore A-23187, particulate phagocytic stimuli and endotoxin. The synthesis of cyclooxygenase products was inhibited by low doses of indomethacin (ID50=0.6 microM) while the synthesis of TXB2 and HHT was selectively inhibited by benzylimidazole (ID50=9.5 microM). Identification of a probable lipoxygenase product is being pursued. The synthesis of this product is not inhibited by indomethacin and migrates with an Rf value close to 5,12-diHETE in TLC. P388D1 and RAW264.7 cells metabolize exogenous AA to the same products as J774.2, but in different proportions, while PU-5-1R does not produce cyclooxygenase metabolites to any appreciable extent.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Cell Line; Cyclooxygenase Inhibitors; Dinoprost; Dinoprostone; Fatty Acids, Unsaturated; Hydroxy Acids; Imidazoles; Indomethacin; Kinetics; Macrophages; Mice; Neoplasms, Experimental; Prostaglandin D2; Prostaglandins D; Prostaglandins E; Prostaglandins F; Thromboxane B2; Thromboxane-A Synthase