Gating characteristics of a steeply voltage-dependent gap junction channel in rat schwann cells

M. Chanson, K. J. Chandross, M. B. Rook, J. A. Kessler, D. C. Spray*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


The gating properties of macroscopic and microscopic gap junctional currents were compared by applying the dual whole cell patch damp technique to pairs of neonatal rat Schwann cells. In response to transjunctional voltage pulses (Vj), macroscopic gap junctional currents decayed exponentially with time constants ranging from < 1 to < 10 s before reaching steady-state levels. The relationship between normalized steady-state junctional conductance (Gss) and (Vj) was well described by a Boltzmann relationship with e-fold decay per 10.4 mV, representing an equivalent gating charge of 2.4. At Vj > 60 mV, Gss was virtually zero, a property that is unique among the gap junctions characterized to date. Determination of opening and closing rate constants for this process indicated that the voltage dependence of macroscopic conductance was governed predominantly by the closing rate constant. In 78% of the experiments, a single population of unitary junctional currents was detected corresponding to an unitary channel conductance of ~ 40 pS. The presence of only a limited number of junctional channels with identical unitary conductances made it possible to analyze their kinetics at the single channel level. Gating at the single channel level was further studied using a stochastic model to determine the open probability (P0) of individual channels in a multiple channel preparation. P0 decreased with increasing Vj following a Boltzmann relationship similar to that describing the macroscopic Gss voltage dependence. These results indicate that, for Vj of a single polarity, the gating of the 40 pS gap junction channels expressed by Schwann cells can be described by a first order kinetic model of channel transitions between open and closed states.

Original languageEnglish (US)
Pages (from-to)925-946
Number of pages22
JournalJournal of General Physiology
Issue number5
StatePublished - Nov 1 1993

ASJC Scopus subject areas

  • Physiology

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