Outward prejunctional I _Na drives the Na ⁺ transfer mechanism for narrow clefts and large total I _Na conductance. (A–C) The prejunctional (solid) and postjunctional (dashed) I_Na are shown as functions of time for the baseline/polarized (green) and mix/homogeneous-polarized (red) distributions for different cleft width w of (A) 5, (B) 10, and (C) 20 nm and increasing values of the relative total I_Na conductance $fNatotal$⁠. CV values (in cm/s) are shown for each simulation. Parameters: f_Na = 0.7, g_gap = 100 nS. Note the baseline $fNatotal=1$ corresponds with g_Na of 16 mS/cm².