title: Platelet-derived growth factor causes endothelium-independent relaxation of rabbit mesenteric artery via the release of a prostanoid.
abstract: Recent evidence has indicated that the mitogen platelet-derived growth factor (PDGF) can act acutely to regulate arterial tone. In this study we demonstrate that the BB isoform of PDGF (PDGF-BB) can cause endothelium-independent relaxation of rabbit isolated mesenteric arteries. In endothelium-denuded arteries, PDGF-BB (40 pM - 8.0 nM) caused concentration-dependent relaxation of noradrenaline-induced tone. The relaxation to PDGF-BB was abolished by a cyclo-oxygenase inhibitor, indomethacin (10 microM) and by the PDGF receptor-associated tyrosine kinase inhibitor, tyrphostin AG1295 (50 microM), but not by N:(G)-monomethyl-L-arginine (L-NMMA, 200 microM), an inhibitor of nitric oxide (NO) synthase. PDGF-BB (4.0 nM) significantly increased the release of prostacyclin (PGI(2)) in endothelium-denuded arteries. Exogenously applied iloprost (1 microM), a stable analogue of PGI(2), relaxed the endothelium-denuded artery. PDGF-BB (4.0 nM) significantly increased the cyclic AMP content. In the absence of Ca(2+), PDGF-BB (4.0 nM) failed to relax the artery, and the release of PGI(2) was almost completely suppressed. In addition, the release of PGI(2) by PDGF-BB (4.0 nM) was significantly reduced in the presence of endothelium. The effect of endothelium was eliminated by L-NMMA (200 microM) and PGI(2) release increased. These data indicate that in rabbit mesenteric arteries, PDGF-BB can evoke endothelium-independent relaxation by stimulating the synthesis of PGI(2). The PDGF-BB-induced prostaglandin synthesis is dependent on both Ca(2+) and tyrosine phosphorylation of the PDGF receptor, and is attenuated by endothelium-derived NO.
authors.affiliation: Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yamawaki
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Hori
authors.forename: H
authors.initials: H
authors.lastname: Ozaki
authors.forename: H
authors.initials: H
authors.lastname: Karaki
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D019332:Endothelin-1; D004791:Enzyme Inhibitors; D010982:Platelet-Derived Growth Factor; D019323:omega-N-Methylarginine; D011464:Epoprostenol; D000242:Cyclic AMP; D002118:Calcium; D009638:Norepinephrine