Figure 1.

Electric circuit representations of the junction between adjacent cells. A, Noncleft model. The extracellular potential was assumed to be 0 (extensive medium). Adjacent cells interact only through current flowing across the gap-junctional resistance (R_gap). B, Cleft model. The extracellular potential (V_e) was assumed to be 0 except at the junction, where V_e was computed at 3 nodes (pre- and postjunctional V_e,disk, V_e,cleft). In addition to the gap-junctional current, adjacent cells interact through extracellular currents flowing in the extracellular cleft across the T-shaped network of its axial (R_cl) and radial (R_radial) resistances, respectively. See text for details.