Simulation of cell–cell coupling through soma-somatic GJs. (A) The scheme illustrates two cells, each exhibiting an excitability described by H-H formalism and communicating through GJs operating according with an S16SM or an MC16SM. The left electrode was used to inject current (Iext) under current clamp mode and measure transmembrane voltage in cell 1 (Vm,1). The right electrode was used to record transmembrane voltage in cell 2 (Vm,2). (B) Electrotonic responses evoked in cell 1 (V1) and cell 2 (V2) by an Iext step of −4 pA. Simulations were performed using an MC16SM. (C) Simulation of changes in Vm,1, Vm,2, and gj caused by gating of GJs formed of the Cx exhibiting properties similar to Cx45, in response to an Iext step of −18 pA. Simulation was performed using an MC16SM. The left inset in the Vm time plot shows that before reaching a steady state, Vm,1 increases and Vm,2 decays, resulting in an increase of Vj and Vj gating. Phase differences between APs arising at the end of the Iext step caused a bipolar Vj spike (inset in Vj time plot) and, consequently, a small decay of gj (inset in gj time plot) caused by Vj gating. (D) Simulation as in A, but performed using an S16SM instead of an MC16SM and assuming that the junction contains 10 GJ channels.
