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Article: Characterization of postjunctional alpha-1 and alpha-2 adrenoceptors activated by exogenous or nerve-released norepinephrine in the canine saphenous vein

TitleCharacterization of postjunctional alpha-1 and alpha-2 adrenoceptors activated by exogenous or nerve-released norepinephrine in the canine saphenous vein
Authors
Issue Date1984
PublisherAmerican Society for Pharmacology and Experimental Therapeutics. The Journal's web site is located at http://jpet.aspetjournals.org
Citation
Journal Of Pharmacology And Experimental Therapeutics, 1984, v. 230 n. 3, p. 699-705 How to Cite?
AbstractExperiments were designed to characterize alpha-1 and alpha-2 adrenoceptor-mediated effects in the canine saphenous vein. Rings of saphenous vein were mounted for isometric tension recording in physiological saline solution. Contractile responses evoked by alpha-1 adrenoceptor agonists, cirazoline or St 587 were inhibited by alpha-1 antagonists, prazosin (pA2 = 7.9) or phenoxybenzamine, but were relatively resistant to the alpha-2 adrenoceptor antagonist rauwolscine. The responses to alpha-2 adrenoceptor agonists, xylazine or B-HT 920, were relatively resistant to prazosin or phenoxybenzamine but were antagonized by rauwolscine (pA2 = 8.7). After phenoxybenzamine, the alpha-2 agonists, M-7, guanfacine, UK 14304, B-HT 920 and xylazine evoked similar maximal increases in tension which were considerably smaller (approximately 50%) than that attained by alpha-1 adrenoceptor stimulation. The different concentration effect characteristics of these responses were also revealed using norepinephrine. Prazosin produced a biphasic effect on the concentration-response curve of norepinephrine, being more potent against responses above 50% of the maximum (pA2 = 7.9) compared to lower increases in tension (pA2 = 6.2). After alpha-1 adrenoceptor blockade with prazosin, rauwolscine was more effective against responses below 50% of the maximum, compared to higher increases in tension. The results suggest that the alpha-1 and alpha-2 adrenoceptor-mediated concentration-effect curves to norepinephrine are almost coincident and that alpha-2 adrenergic stimulation produces only partial activation of the vascular smooth muscle. Contractile responses produced by sympathetic nerve stimulation or by tyramine were antagonized more effectively by the combination of prazosin plus rauwolscine than by either blocker given alone, suggesting that alpha-1 and alpha-2 adrenoceptors are both innervated by sympathetic nerves in the canine saphenous vein.
Persistent Identifierhttp://hdl.handle.net/10722/170716
ISSN
2015 Impact Factor: 3.76
2015 SCImago Journal Rankings: 1.847
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorFlavahan, NAen_US
dc.contributor.authorRimele, TJen_US
dc.contributor.authorCooke, JPen_US
dc.contributor.authorVanhoutte, PMen_US
dc.date.accessioned2012-10-30T06:10:34Z-
dc.date.available2012-10-30T06:10:34Z-
dc.date.issued1984en_US
dc.identifier.citationJournal Of Pharmacology And Experimental Therapeutics, 1984, v. 230 n. 3, p. 699-705en_US
dc.identifier.issn0022-3565en_US
dc.identifier.urihttp://hdl.handle.net/10722/170716-
dc.description.abstractExperiments were designed to characterize alpha-1 and alpha-2 adrenoceptor-mediated effects in the canine saphenous vein. Rings of saphenous vein were mounted for isometric tension recording in physiological saline solution. Contractile responses evoked by alpha-1 adrenoceptor agonists, cirazoline or St 587 were inhibited by alpha-1 antagonists, prazosin (pA2 = 7.9) or phenoxybenzamine, but were relatively resistant to the alpha-2 adrenoceptor antagonist rauwolscine. The responses to alpha-2 adrenoceptor agonists, xylazine or B-HT 920, were relatively resistant to prazosin or phenoxybenzamine but were antagonized by rauwolscine (pA2 = 8.7). After phenoxybenzamine, the alpha-2 agonists, M-7, guanfacine, UK 14304, B-HT 920 and xylazine evoked similar maximal increases in tension which were considerably smaller (approximately 50%) than that attained by alpha-1 adrenoceptor stimulation. The different concentration effect characteristics of these responses were also revealed using norepinephrine. Prazosin produced a biphasic effect on the concentration-response curve of norepinephrine, being more potent against responses above 50% of the maximum (pA2 = 7.9) compared to lower increases in tension (pA2 = 6.2). After alpha-1 adrenoceptor blockade with prazosin, rauwolscine was more effective against responses below 50% of the maximum, compared to higher increases in tension. The results suggest that the alpha-1 and alpha-2 adrenoceptor-mediated concentration-effect curves to norepinephrine are almost coincident and that alpha-2 adrenergic stimulation produces only partial activation of the vascular smooth muscle. Contractile responses produced by sympathetic nerve stimulation or by tyramine were antagonized more effectively by the combination of prazosin plus rauwolscine than by either blocker given alone, suggesting that alpha-1 and alpha-2 adrenoceptors are both innervated by sympathetic nerves in the canine saphenous vein.en_US
dc.languageengen_US
dc.publisherAmerican Society for Pharmacology and Experimental Therapeutics. The Journal's web site is located at http://jpet.aspetjournals.orgen_US
dc.relation.ispartofJournal of Pharmacology and Experimental Therapeuticsen_US
dc.subject.meshAnimalsen_US
dc.subject.meshClonidine - Analogs & Derivatives - Pharmacologyen_US
dc.subject.meshDogsen_US
dc.subject.meshDose-Response Relationship, Drugen_US
dc.subject.meshElectric Stimulationen_US
dc.subject.meshFemaleen_US
dc.subject.meshImidazoles - Pharmacologyen_US
dc.subject.meshMaleen_US
dc.subject.meshMethoxamine - Pharmacologyen_US
dc.subject.meshNorepinephrine - Blooden_US
dc.subject.meshPhenoxybenzamine - Pharmacologyen_US
dc.subject.meshPhenylephrine - Pharmacologyen_US
dc.subject.meshPrazosin - Pharmacologyen_US
dc.subject.meshReceptors, Adrenergic, Alpha - Metabolismen_US
dc.subject.meshSaphenous Veinen_US
dc.subject.meshSympathetic Nervous System - Metabolismen_US
dc.subject.meshTyramine - Pharmacologyen_US
dc.subject.meshYohimbine - Pharmacologyen_US
dc.titleCharacterization of postjunctional alpha-1 and alpha-2 adrenoceptors activated by exogenous or nerve-released norepinephrine in the canine saphenous veinen_US
dc.typeArticleen_US
dc.identifier.emailVanhoutte, PM:vanhoutt@hku.hken_US
dc.identifier.authorityVanhoutte, PM=rp00238en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.pmid6088763-
dc.identifier.scopuseid_2-s2.0-0021129748en_US
dc.identifier.volume230en_US
dc.identifier.issue3en_US
dc.identifier.spage699en_US
dc.identifier.epage705en_US
dc.identifier.isiWOS:A1984TJ98900025-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridFlavahan, NA=7006398882en_US
dc.identifier.scopusauthoridRimele, TJ=7004614618en_US
dc.identifier.scopusauthoridCooke, JP=7202378672en_US
dc.identifier.scopusauthoridVanhoutte, PM=7202304247en_US

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