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Article: Efficacy of muscarinic stimulation and mode of excitation-contraction coupling in bovine trachealis muscle

TitleEfficacy of muscarinic stimulation and mode of excitation-contraction coupling in bovine trachealis muscle
Authors
Issue Date2000
PublisherElsevier Inc. The Journal's web site is located at http://www.elsevier.com/locate/lifescie
Citation
Life Sciences, 2000, v. 67 n. 15, p. 1833-1846 How to Cite?
AbstractWe have compared the efficacy of cromakalim and nifedipine to inhibit acetylcholine (ACh) and pilocarpine-induced tonic contractions in control preparations and in tissues where a fraction of the muscarinic receptor population had been removed by alkylation with phenoxybenzamine (PBZ). Both agonists induced contractions by stimulating pharmacologically similar receptors, probably of the M3 muscarinic subtype. The receptor reserve was larger, and the coupling between stimulation and contraction (E-C coupling) more efficient when ACh was the stimulating agonist. For stimulations that produced equal levels of muscle response, cromakalim was more efficacious in inhibiting contractions induced by pilocarpine. The efficacy of cromakalim in relaxing contractions induced by ACh increased when the number of functional receptors decreased. Cromakalim and nifedipine decreased the efficiency of E-C coupling for ACh and pilocarpine. Cromakalim efficacy decreased in a sigmoid manner when stimulating concentrations of ACh (and receptor occupancy) increased, and there was an inverse relationship between receptor occupancy by ACh and cromakalim efficacy. In the presence of TEA, a K+ channel blocker, nifedipine almost completely inhibited contractions induced by the M3 muscarinic agonist bethanechol. These data indicate that in bovine tracheal smooth muscle, electro-mechanical coupling is an inherent part of muscarinic E-C coupling, but its functional expression is dependent upon the efficacy of stimulation. The data also suggest that the M3 receptor is coupled to a cellular pathway linked with the activation of K+ channels that exerts a potent functional antagonism against activation of voltage-dependent Ca2+ entry. © 2000 Elsevier Science Inc. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/171679
ISSN
2015 Impact Factor: 2.685
2015 SCImago Journal Rankings: 1.056
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorShen, Sen_US
dc.contributor.authorHuang, Yen_US
dc.contributor.authorBourreau, JPen_US
dc.date.accessioned2012-10-30T06:16:19Z-
dc.date.available2012-10-30T06:16:19Z-
dc.date.issued2000en_US
dc.identifier.citationLife Sciences, 2000, v. 67 n. 15, p. 1833-1846en_US
dc.identifier.issn0024-3205en_US
dc.identifier.urihttp://hdl.handle.net/10722/171679-
dc.description.abstractWe have compared the efficacy of cromakalim and nifedipine to inhibit acetylcholine (ACh) and pilocarpine-induced tonic contractions in control preparations and in tissues where a fraction of the muscarinic receptor population had been removed by alkylation with phenoxybenzamine (PBZ). Both agonists induced contractions by stimulating pharmacologically similar receptors, probably of the M3 muscarinic subtype. The receptor reserve was larger, and the coupling between stimulation and contraction (E-C coupling) more efficient when ACh was the stimulating agonist. For stimulations that produced equal levels of muscle response, cromakalim was more efficacious in inhibiting contractions induced by pilocarpine. The efficacy of cromakalim in relaxing contractions induced by ACh increased when the number of functional receptors decreased. Cromakalim and nifedipine decreased the efficiency of E-C coupling for ACh and pilocarpine. Cromakalim efficacy decreased in a sigmoid manner when stimulating concentrations of ACh (and receptor occupancy) increased, and there was an inverse relationship between receptor occupancy by ACh and cromakalim efficacy. In the presence of TEA, a K+ channel blocker, nifedipine almost completely inhibited contractions induced by the M3 muscarinic agonist bethanechol. These data indicate that in bovine tracheal smooth muscle, electro-mechanical coupling is an inherent part of muscarinic E-C coupling, but its functional expression is dependent upon the efficacy of stimulation. The data also suggest that the M3 receptor is coupled to a cellular pathway linked with the activation of K+ channels that exerts a potent functional antagonism against activation of voltage-dependent Ca2+ entry. © 2000 Elsevier Science Inc. All rights reserved.en_US
dc.languageengen_US
dc.publisherElsevier Inc. The Journal's web site is located at http://www.elsevier.com/locate/lifescieen_US
dc.relation.ispartofLife Sciencesen_US
dc.rightsLife Sciences. Copyright © Elsevier Inc.-
dc.subject.meshAcetylcholine - Pharmacologyen_US
dc.subject.meshAnimalsen_US
dc.subject.meshCalcium - Metabolismen_US
dc.subject.meshCattleen_US
dc.subject.meshCromakalim - Pharmacologyen_US
dc.subject.meshDiamines - Pharmacologyen_US
dc.subject.meshDose-Response Relationship, Drugen_US
dc.subject.meshDrug Interactionsen_US
dc.subject.meshMuscarinic Agonists - Pharmacologyen_US
dc.subject.meshMuscle Contraction - Drug Effects - Physiologyen_US
dc.subject.meshMuscle, Smooth - Drug Effects - Physiologyen_US
dc.subject.meshNifedipine - Pharmacologyen_US
dc.subject.meshPhenoxybenzamine - Pharmacologyen_US
dc.subject.meshPilocarpine - Pharmacologyen_US
dc.subject.meshPiperidines - Pharmacologyen_US
dc.subject.meshPirenzepine - Pharmacologyen_US
dc.subject.meshReceptors, Muscarinic - Drug Effectsen_US
dc.subject.meshStress, Mechanicalen_US
dc.subject.meshTetraethylammonium - Pharmacologyen_US
dc.subject.meshTrachea - Drug Effects - Physiologyen_US
dc.titleEfficacy of muscarinic stimulation and mode of excitation-contraction coupling in bovine trachealis muscleen_US
dc.typeArticleen_US
dc.identifier.emailBourreau, JP:bourreau@hkucc.hku.hken_US
dc.identifier.authorityBourreau, JP=rp00389en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/S0024-3205(00)00768-2-
dc.identifier.pmid11043606-
dc.identifier.scopuseid_2-s2.0-0034267477en_US
dc.identifier.hkuros63591-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0034267477&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume67en_US
dc.identifier.issue15en_US
dc.identifier.spage1833en_US
dc.identifier.epage1846en_US
dc.identifier.isiWOS:000089990600004-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridShen, S=7403431355en_US
dc.identifier.scopusauthoridHuang, Y=7501573013en_US
dc.identifier.scopusauthoridBourreau, JP=7003927886en_US

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