All vertebrate gap junction channels display voltage-dependent gating. Historically, voltage-dependent behaviors have been characterized as being transjunctional voltage (Vj) and membrane voltage (Vm) dependent. The transjunctional voltage dependence of gap junction channels composed of two identical hemichannels, each composed of identical connexins subunits (a homotypic channel) is usually symmetric and is often referred as Vj-dependent gating. Vj steps of equal amplitude but opposite polarity will result in junctional currents that are mirror images of each other in terms of magnitude and kinetics (Harris et al. 1981; Spray et al. 1981). Figure 1 in Oh et al. 2000 illustrates such symmetric (slow) Vj dependence, as well as the characteristic steady state “residual” junctional conductance.
It is interesting to note that the first demonstration of voltage dependence in cell-to-cell communication is best considered to be a subset of...
