title: Endothelium-dependent relaxant action of platelet activating factor in the rat mesenteric artery.
abstract: Vasorelaxant action of platelet activating factor (PAF) was examined in perfused mesenteric vascular beds and mesenteric artery strips isolated from rats. PAF caused a dose-dependent vasodilation of norepinephrine-contracted mesenteric vascular bed, which was sensitive to CV-3988, a PAF antagonist, but insensitive to tetrodotoxin, atropine, propranolol and indomethacin. PAF also caused a relaxation of phenylephrine-contracted mesenteric artery strips at above 3 X 10(-12) M. Much higher concentrations of PAF were required to relax the aorta, carotid and pulmonary arteries. The PAF- and acetylcholine (ACh)-induced relaxations of mesenteric artery were dependent on the presence of endothelium and were inhibited by either hydroquinone and methylene blue, which inhibit the action of endothelium-derived relaxing factor (EDRF), or L-canavanine, which inhibits the formation of nitric oxide from L-arginine. Phospholipase A2 inhibitors such as quinacrine and ONO-RS-082 abolished the relaxation induced by ACh but did not affect that by PAF. Thus, PAF induces a vasorelaxation by releasing EDRF from endothelial cells as ACh does, although the pathway to produce the substances by PAF may be different from that by ACh.
authors.affiliation: Department of Veterinary Pharmacology, Faculty of Agriculture, Miyazaki University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Chiba
authors.forename: N
authors.initials: N
authors.lastname: Mikoda
authors.forename: H
authors.initials: H
authors.lastname: Kawasaki
authors.forename: K
authors.initials: K
authors.lastname: Ito
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology*; D006873:Hydroquinones / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009569:Nitric Oxide / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D006873:Hydroquinones; D010972:Platelet Activating Factor; D010656:Phenylephrine; D009569:Nitric Oxide; D013779:Tetrodotoxin; D001285:Atropine; D011433:Propranolol; D010741:Phospholipases A; D054467:Phospholipases A2; D007545:Isoproterenol; D000109:Acetylcholine; C031927:hydroquinone; D007213:Indomethacin