Pflügers Archiv

, Volume 431, Issue 5, pp 775–785

Connexin43 gap junctions exhibit asymmetrical gating properties

  • Kathrin Banach
  • Robert Weingart
Original Article

DOI: 10.1007/BF02253843

Cite this article as:
Banach, K. & Weingart, R. Pflugers Arch. (1996) 431: 775. doi:10.1007/BF02253843

Abstract

A communication-deficient cell line (RIN cells, derived from a rat islet tumour), stably transfected with cDNA coding for rat connexin43 (Cx43), was chosen to further assess the mechanism of voltage gating of Cx43 gap junction channels. The experiments were carried out on preformed cell pairs using a dual whole-cell, voltage-clamp method. The junctional current,Ij, revealed a time- and voltage-dependent inactivation at transjunctional voltagesVj > ± 40mV When an asymmetrical pulse protocol was used (in cell 1 the holding potential was maintained, in cell 2 it was altered to establish a variableVj), the channels exhibited an asymmetrical gating behaviour:Vj,O = −73.7 mV and 65.1 mV for negative and positiveVj, respectively (Vj at whichIj is half-maximally inactivated); gj(min) = 0.34 and 0.29 (normalized minimal conductance); τ = 350 ms and 80 ms atVj = 100 mV (time constant ofIj inactivation). Hence, these parameters were more sensitive to positiveVj values. When a symmetrical pulse protocol was used (the holding potentials in cell 1 and cell 2 were altered simultaneously in steps of equal amplitude but of opposite polarity), theVj —dependent asymmetries were absent:Vj,O = −60.5 and 59.5; gj (min) = 0.27 and 0.29; τ = 64 ms and 47 ms at 100 mV Putative explanations for these obervations are discussed. A possibility is that the number of channels alters with the polarity ofVj.

Key words

RatPancreasRIN cellsGap junctionsConnexin43Biophysical propertiesVoltage gating

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • Kathrin Banach
    • 1
  • Robert Weingart
    • 1
  1. 1.Department of PhysiologyUniversity of BernBernSwitzerland
  2. 2.Department of PharmacologySUNY Health Science CenterSyracuseUSA