Endothelium-dependent vasodilatation in bovine coronary arteries: calcium dependence and inhibition by proadifen.
Vasodilator responses were examined in bovine coronary artery rings preconstricted with the thromboxane-mimetic, U46619. A23187 produced endothelium-dependent vasodilatation that was abolished in calcium-free solution. In contrast, endothelium-dependent vasodilatation produced by arachidonic acid was not altered in calcium-free solution. In calcium-free solution, indomethacin (10 mumol/l) did not affect arachidonate-induced relaxations whereas BW755C (100 mumol/l) reduced relaxations to low concentrations of arachidonate, and proadifen (SKF-525A, 1 mmol/l) abolished them at all concentrations. Endothelium-independent relaxations produced by glyceryl trinitrate were not affected by proadifen (1 mmol/l). It is clear that arachidonic acid bypasses a calcium-dependent step in the release of endothelium-derived relaxing factor, perhaps acting as an intermediate precursor. The data support the hypothesis that a cytochrome P-450 mono-oxygenase may also be involved.
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D003331:Coronary Vessels / Q000187:drug effects*; D004727:Endothelium / Q000502:physiology; D066298:In Vitro Techniques; D011335:Proadifen / Q000494:pharmacology*; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
D001095:Arachidonic Acids; D011450:Prostaglandin Endoperoxides, Synthetic; D016718:Arachidonic Acid; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D011335:Proadifen; D002118:Calcium