FIG. 10.
Simulated effects of gap junction distribution and cell size on cell-to-cell propagation delay and maximal upstroke velocity (dV/dtmax) of the transmembrane action potential. Panels (a) and (b) show four different cell types, two real cell types, and two fictive cell types. Cell type a corresponds to real dog ventricular myocyte of relatively large size with gap junctions predominantly at cell ends. Cell type b corresponds to a fictive myocyte of the size of a dog cell, but with gap junctions distributed regularly around the cell perimeter, typical for a rat neonatal ventricular myocyte. Cell type c corresponds to a fictive myocyte that has the small size of a rat ventricular myocyte, with gap junctions located predominantly at cell end (dog pattern). Cell type d represents a real rat neonatal ventricular myocyte with a relatively small size and gap junctions spaced regularly around the cell perimeter. Comparison of all four cell types illustrates that cell-to-cell propagation delays [panel (a)] and the maximal upstroke velocity of the transmembrane action potential [panel (b)] predominantly depend on cell size, whereas the gap junction distribution patterns play a minor role. Reproduced with permission from M. S. Spach et al., Circ. Res. 86, 3 (2000). Copyright 2000 Wolters Kluwer Health, Inc.69