Propagation of simulated action potentials (APs) in a single linear chain of 100 myocardial cells. Cell #1 was stimulated intracellularly, and the resultant APs were recorded from only cells #1, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 (to limit the number of traces). The number of gap-junction (g-j) channels at the cell junctions was varied over a wide range, but only five are illustrated, namely 0 gj-channels (A), 300 (B), 1,000 (C), 3,000 (D), and 10,000. The traces numbered in panel A are for APs recorded from cells #1, 10, 20, and 100; the remaining traces are bunched up between cells 20 and 100, some of them being nearly superimposed. Note that adding gj-channels markedly speeds up the velocity of propagation. In panel E, all 11 traces are superimposed.