title: Selective agonists reveal alpha(1A)- and alpha(1B)-adrenoceptor subtypes in caudal artery of the young rat.
abstract: Multiple alpha(1)-adrenoceptors were evaluated in caudal artery of the young Wistar rat using selective agonists and antagonists. Arteries were exposed to the selective alpha(1A)-adrenoceptor agonist, A-61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) or to phenylephrine and to prazosin (alpha(1)-adrenoceptor antagonist), or the selective alpha(1A)-adrenoceptor antagonists 5-methylurapidil, RS 100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy)phenyl]-1-piperazinyl]propyl]-2,4-(1H)-pyrimidinedione), RS 17053 (N-[2(2-cyclopropylmethoxy) ethyl]-5-chloro-alpha, alpha-dimethyl-1H-indole-3-ethanamide), and the selective alpha(1D)-adrenoceptor antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione). Results showed a 100-fold higher potency of A-61603 for the alpha(1)-adrenoceptor present in the artery, compared with phenylephrine. Prazosin displaced both agonists with high affinity, whereas 5-methylurapidil, RS 100329 and RS 17053 displaced A-61603 with high affinity, indicating the presence of alpha(1A)-adrenoceptors. The selective alpha(1A)-adrenoceptor antagonists blocked phenylephrine responses with low affinity, suggesting that phenylephrine activated a second receptor population in caudal artery. BMY 7378 antagonized with low affinity both A-61603 and phenylephrine-induced contractions, indicating absence of alpha(1D)-adrenoceptors in the vessel. The results suggest that functional alpha(1B)-adrenoceptors are present in caudal arteries of the young Wistar rat.
authors.affiliation: Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Sede Sur, Mexico, D.F.
authors.forename: J
authors.initials: J
authors.lastname: Parés-Hipólito
authors.forename: J H
authors.initials: JH
authors.lastname: Gómez-Zamudio
authors.forename: I A
authors.initials: IA
authors.lastname: Gallardo-Ortiz
authors.forename: J J
authors.initials: JJ
authors.lastname: López-Guerrero
authors.forename: J
authors.initials: J
authors.lastname: Santamaría-Ortiz
authors.forename: M
authors.initials: M
authors.lastname: Ibarra
authors.forename: R
authors.initials: R
authors.lastname: Villalobos-Molina
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000187:drug effects* / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology; D013623:Tail / Q000098:blood supply*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D013941:Thymine / Q000494:pharmacology
chemical_list: C094643:A 61603; C547715:Adra1a protein, rat; C547718:Adra1b protein, rat; D058646:Adrenergic alpha-1 Receptor Agonists; D058668:Adrenergic alpha-1 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D007093:Imidazoles; D007211:Indoles; D010879:Piperazines; C120711:RS 100329; C099495:RS 17053; D018340:Receptors, Adrenergic, alpha-1; D013764:Tetrahydronaphthalenes; D010656:Phenylephrine; D002217:Carbachol; C053428:BMY 7378; D013941:Thymine; D011224:Prazosin