title: Neonatal rat cardiomyocytes show characteristics of nonhomotypic gap junction channels.
abstract: Neonatal rat cardiomyocytes mainly coexpress the connexins Cx40, Cx43, and to a small amount Cx45, leading to potential formation of mixed (heteromeric/heterotypic) gap junction channels. Using the dual-voltage clamp technique with switching clamp circuits, the authors investigated voltage sensitivity of gap junction channels between cell pairs of Cx40, Cx43, and Cx45 stably transfected HeLa cells and compared those data to data obtained from cell pairs of cultured neonatal rat cardiomyocytes. In accordance to previously published data, the relationship between normalized conductance and transjunctional voltage (g/V(j)) was quasisymmetrical for the transfected HeLa cells, indicating homotypic gap junction channels. Boltzmann curves fitted to data obtained from neonatal rat cardiomyocyte pairs expressing both Cx40 and Cx43 showed an asymmetrical inactivation pattern, which cannot be explained by the presence of pure populations of homotypic gap junction channels of either isoform. In conclusion the authors assume the additional presence of heterotypic and possibly even heteromeric gap junction channels in neonatal rat cardiomyocytes.
authors.affiliation: Institut fur Pharmakologie und Toxikologie, Universitatsklinikum Münster, Münster, Germany. J.S.Schulte@uni-muenster.de
authors.forename: Jan Sebastian
authors.initials: JS
authors.lastname: Schulte
authors.forename: Anja
authors.initials: A
authors.lastname: Scheffler
authors.forename: Diana
authors.initials: D
authors.lastname: Rojas-Gomez
authors.forename: F W
authors.initials: FW
authors.lastname: Mohr
authors.forename: Stefan
authors.initials: S
authors.lastname: Dhein
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D018031:Connexin 43 / Q000502:physiology*; D017630:Connexins / Q000502:physiology*; D017629:Gap Junctions / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000097003:Gap Junction alpha-5 Protein
chemical_list: D018031:Connexin 43; D017630:Connexins; D007473:Ion Channels; D000097003:Gap Junction alpha-5 Protein