title: Characterization of 5-hydroxytryptamine-induced contraction and acetylcholine-induced relaxation in isolated chicken basilar artery.
abstract: The aim of the present study was to clarify the responsiveness of the chicken basilar artery to 5-hydroxytryptamine (5-HT) and acetylcholine (ACh) and to characterize the related receptor subtypes in vitro. Basilar arteries were obtained from freshly slaughtered broiler chickens. The 5-HT induced concentration-dependent contraction of the arteries. The concentration-response curves for 5-HT were shifted 30-fold to the right by methiothepin (a 5-HT(1) and 5-HT(2) receptor antagonist) and 3-fold to the right by ketanserin (a 5-HT(2) receptor antagonist). In the presence of ketanserin, the concentration-response curve for 5-HT was shifted 10-fold to the right by methiothepin. The pA(2) value for methiothepin was 8.26. The ACh induced concentration-dependent relaxation under conditions of precontraction by 5-HT. The concentration-response curve for ACh was shifted to the right by atropine [a nonselective muscarinic (M) receptor antagonist] and hexahydro-sila-difenidol hydrochloride, a p-fluoroanalog (pFHHSiD, an M(3) receptor antagonist), but not by pirenzepine (an M(1) receptor antagonist) or methoctramine (an M(2) receptor antagonist). The pA(2) value for pFHHSiD was 7.55. Nω-Nitro-l-arginine (a nitric oxide synthase inhibitor) inhibited ACh-induced relaxation by approximately 50%. These results suggest that 5-HT induces contraction via activation of 5-HT(1) and 5-HT(2) receptors and that ACh induces relaxation via activation of the M(3) receptor. The 5-HT(1) receptor might play a dominant role in 5-HT-induced contraction. One of the factors involved in ACh-induced relaxation is probably nitric oxide released from endothelial cells.
authors.affiliation: Department of Veterinary Pharmacology, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Matsumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Obi
authors.forename: M Z
authors.initials: MZ
authors.lastname: Islam
authors.forename: E
authors.initials: E
authors.lastname: Yamazaki-Himeno
authors.forename: M
authors.initials: M
authors.lastname: Shiraishi
authors.forename: A
authors.initials: A
authors.lastname: Miyamoto
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001488:Basilar Artery / Q000187:drug effects*; D002645:Chickens; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D008719:Methiothepin / Q000494:pharmacology; D019335:Nitroarginine / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D010276:Parasympatholytics; D012702:Serotonin Antagonists; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D019335:Nitroarginine; D012701:Serotonin; D008719:Methiothepin; D007650:Ketanserin; D000109:Acetylcholine