Figure 1

Diagrams of the arrangement of the myocardial cells and smooth muscle cells, basic units, and key resistances for the 5 × 5 model: 5 parallel chains (A – E) of 5 cells each (1 – 5). There were no low-resistance connections between cells within a chain or between chains. The surface membrane of each cell was represented by 2 basic units (one upwards and one inverted), and each junctional membrane by one unit each. The radial junctional cleft resistance (R_jc) is depicted, as is the longitudinal resistance of the interstitial space between the chains. Propagation of simulated action potentials was examined when only one cell of one chain was electrically stimulated (usually cell ^#1 of the A-chain (cell A1)).