omega-Conotoxins block neurotransmission in the rat vas deferens by binding to different presynaptic sites on the N-type Ca2+ channel

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dc.contributor.authorHirata, H.
dc.contributor.authorAlbillos, A.
dc.contributor.authorFernandez, F.
dc.contributor.authorMedrano, J.
dc.contributor.authorJurkiewicz, A.
dc.contributor.authorGarcia, A. G.
dc.contributor.institutionUNIV AUTONOMA MADRID
dc.contributor.institutionUniversidade Federal de São Paulo (UNIFESP)
dc.date.accessioned2016-01-24T12:30:18Z
dc.date.available2016-01-24T12:30:18Z
dc.date.issued1997-02-26
dc.description.abstractElectrically-induced twitch responses of the prostatic segment of vas deferens (0.1 Hz, 65 V, 1 ms) are mainly due to the transient presynaptic release of ATP, which acts postsynaptically on non-adrenergic receptors to contract smooth muscle cells. These responses were fully blocked by nanomolar concentrations of the omega-conotoxins GVIA, MVIIA, and MVIIC, most likely by inhibiting Ca2+ entry through presynaptic N-type Ca2+ channels controlling the release of ATP. Repeated washout of the toxins allowed the recovery of contractions, except for omega-conotoxin GVIA, whose inhibitory effects remained unchanged for at least 60 min. in addition, micromolar concentrations of omega-conotoxin MVIIC were unable to protect against the irreversible inhibition of twitch contractions induced by nanomolar concentrations of omega-conotoxin GVIA, At low extracellular Ca2+ concentrations (1.5 mM), 20 nM of omega-conotoxin GVIA or MVIIA inhibited completely the twitch contractions in about 10 min. in 5 mM Ca2+ the blockade of twitch contractions after 10 min was 70% for both toxins. in 1.5 mM Ca2+ omega-conotoxin MVIIC (1 mu M) inhibited completely the twitch contraction after 10 min. in 5 mM Ca2+ blockade developed very slowly and was very poor after 30 min, omega-conotoxin MVIIC depressed the response by only 20%. These results are compatible with the idea that the three omega-conotoxins block the purinergic neurotransmission of the vas deferens by acting on presynaptic N-type voltage-dependent Ca2+ channels. However, omega-conotoxin MVIIC seems to bind to sites different from those recognised by omega-conotoxin GVIA and MVIIA, which are markedly differentiated by their Ca2+ requirements for binding to their receptors.en
dc.description.affiliationUNIV AUTONOMA MADRID,FAC MED,DEPT FARMACOL,E-28029 MADRID,SPAIN
dc.description.affiliationUNIV AUTONOMA MADRID,HOSP PRINCESA,SERV FARMACOL CLIN,MADRID 28006,SPAIN
dc.description.affiliationUNIV AUTONOMA MADRID,HOSP PRINCESA,INST GERONTOL,MADRID 28006,SPAIN
dc.description.affiliationUNIFESP,ESCOLA PAULISTA MED,DEPT FARMACOL,BR-04034970 São Paulo,BRAZIL
dc.description.affiliationUnifespUNIFESP,ESCOLA PAULISTA MED,DEPT FARMACOL,BR-04034970 São Paulo,BRAZIL
dc.description.sourceWeb of Science
dc.format.extent217-223
dc.identifierhttp://dx.doi.org/10.1016/S0014-2999(96)00951-X
dc.identifier.citationEuropean Journal of Pharmacology. Amsterdam: Elsevier B.V., v. 321, n. 2, p. 217-223, 1997.
dc.identifier.doi10.1016/S0014-2999(96)00951-X
dc.identifier.issn0014-2999
dc.identifier.urihttp://repositorio.unifesp.br/handle/11600/25694
dc.identifier.wosWOS:A1997WL45700011
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofEuropean Journal of Pharmacology
dc.rightsinfo:eu-repo/semantics/restrictedAccess
dc.rights.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dc.subjectCa2+ channelen
dc.subjectomega-conotoxin GVIAen
dc.subjectomega-conotoxin MVIIAen
dc.subjectomega-conotoxin MVIICen
dc.subjectomega-agatoxin IVAen
dc.subjectvas deferensen
dc.subjectpurinergic neurotransmissionen
dc.titleomega-Conotoxins block neurotransmission in the rat vas deferens by binding to different presynaptic sites on the N-type Ca2+ channelen
dc.typeinfo:eu-repo/semantics/article
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