Graphs of the cross-sectional profile through a small-diameter cardiac bundle of the propagation velocities for different numbers of gj-channels: 0 (A), 1 (B), 10 (C), and 100 (D). All other parameters were standard, including Rol2 (200 KΩ) and RBT (200 KΩ). Panel A is the same as panel B of Fig. 3, but it is included again here to facilitate comparison. The profile is bell-shaped (inverted) in A and B, bullet-shaped in C, and flat in D. In C, the velocity at the bundle surface is only slightly faster than that at the core.