Figure 1.

Circuit diagram for a single Hodgkin-Huxley (HH) cell modified to include sodium and potassium currents into a diffusion-limited cleft region. Model includes standard HH transmembrane ionic currents for the lateral membrane and potassium and sodium transmembrane currents for the junctional membrane into the diffusion-limited cleft region. Currents out of the cleft region are governed by a Goldman-Hodgkin-Katz current relationship. The two-cell model has a single and shared cleft potassium concentration [K]_cl, cleft sodium concentration [Na]_cl, cleft width w_f, and cleft resistance r_j parameters. Cellular capacitance and fraction (F_IK) of total potassium current I_K,cl in the cleft can be varied independently for both cells. Supporting materials and methods single_cell_potassium_cleft.m and double_cell_potassium_cleft.m are MATLAB (The MathWorks, Natick, MA) source codes for the single and dual cell models, respectively.