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(Circulation Research. 2000;86:e42.)
© 2000 American Heart Association, Inc.

UltraRapid Communications

Formation of Heterotypic Gap Junction Channels by Connexins 40 and 43

Virginijus Valiunas, Robert Weingart, Peter R. Brink

From the Department of Physiology and Biophysics (V.V., P.R.B.), State University of New York at Stony Brook, NY; Department of Physiology (R.W.), University of Bern, Switzerland.

Correspondence to Peter R. Brink, Department of Physiology and Biophysics, State University of New York at Stony Brook, Stony Brook, NY 11794. E-mail peter{at}patch.pnb.sunysb.edu

Abstract—Gap junctions formed between transfected cells expressing connexin (Cx) 40 and Cx43 (Cx43-RIN, Cx40-HeLa, and Cx43-HeLa) revealed a relationship, g_j=f(V_j), at steady state, that is typified by a nonsymmetrical behavior similar to that previously reported for other heterotypic channels (gap junction conductance [g_j]; transjunctional voltage [V_j]). The unitary conductance of the channels was sensitive to the polarity of V_j. A main state conductance of 61 pS was found when the Cx43 cell was stepped positively or the Cx40 cell negatively (V_j=70 mV); the reverse polarities yielded a conductance of 100 pS. These heterotypic channels were permeable to carboxyfluorescein. In addition, two other heterotypic forms are illustrated to demonstrate that endogenous Cx45 expression cannot explain the results. The demonstration of heterotypic Cx40–Cx43 channels may have implications for the propagation of the electrical impulse in heart. For example, they may contribute to the slowing of the impulse propagation through the junctions between Purkinje fibers and ventricular muscle. The full text of this article is available at http://www.circresaha.org.

Key Words: gap junction • ion channel • electrophysiology

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