CV depends on Na ⁺ channel distribution, gap junctional coupling, and cleft width. CV is shown as a function of gap junction conductance g_gap for (A–G) different Na⁺ channel distributions and cleft width w. CV slows for decreasing g_gap, with sensitivity to cleft width greater for polarized distributions with the shifted and mix I_Na subpopulations. Parameters: f_Na = 0.7.