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Cardiac connexins Cx43 and Cx45: formation of diverse gap junction channels with diverse electrical properties

Desplantez, Thomas ; Halliday, Deborah ; Dupont, Emmanuel ; Weingart, Robert

In: Pflügers Archiv, 2004, vol. 448, no. 4, p. 363-375

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    Titre
    • Cardiac connexins Cx43 and Cx45: formation of diverse gap junction channels with diverse electrical properties
    Auteur
    • Desplantez, Thomas. Physiologisches Institut, Universität Bern, Bühlplatz 5, 3012, Bern, Switzerland
    • Halliday, Deborah. National Heart and Lung Institute (Imperial College London), Royal Brompton Hospital, Sydney Street, SW3 6NP, London, UK
    • Dupont, Emmanuel. National Heart and Lung Institute (Imperial College London), Royal Brompton Hospital, Sydney Street, SW3 6NP, London, UK
    • Weingart, Robert. Physiologisches Institut, Universität Bern, Bühlplatz 5, 3012, Bern, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Pflügers Archiv, 2004, vol. 448, no. 4, p. 363-375. Springer-Verlag; http://www.springer.de
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:319101
    Summary
    HeLa cells expressing rat connexin43 (Cx43) and/or mouse Cx45 were studied with the dual voltage-clamp technique. Different types of cell pairs were established and their gap junction properties determined, i.e. the dependence of the instantaneous and steady-state conductances (g j,inst, g j,ss) on the transjunctional voltage (V j) and the kinetics of inactivation of the gap junction current (I j). Pairs of singly transfected cells showed homogeneous behaviour at both V j polarities. Homotypic Cx43-Cx43 and Cx45-Cx45 cell pairs yielded distinct symmetrical functions g j,inst=f(V j) and g j,ss=f(V j). Heterotypic Cx43-Cx45 preparations exhibited asymmetric functions g j,inst=f(V j) and g j,ss=f(V j) suggesting that connexons Cx43 and Cx45 gate with positive and negative V j, respectively. Preparations containing a singly (Cx43 or Cx45) or doubly (Cx43/45) transfected cell showed quasi-homogeneous behaviour at one V j polarity and heterogeneous behaviour at the other polarity. The former yielded Boltzmann parameters intermediate between those of Cx43-Cx43, Cx45-Cx45 and Cx43-Cx45 preparations; the latter could not be explained by homotypic and heterotypic combinations of homomeric connexons. Each pair of doubly transfected cells (Cx43/Cx45) yielded unique functions g j,inst=f(V j) and g j,ss=f(V j). This can not be explained by combinations of homomeric connexons. We conclude that Cx43 and Cx45 form homomeric-homotypic, homomeric-heterotypic channels as well as heteromeric-homotypic and heteromeric-heterotypic channels. This has implications for the impulse propagation in specific areas of the heart