Modulation of conduction velocity by nonmyocytes in the low coupling regime.

This paper explores the conditions under which nonmyocytes, when electrically coupled to myocytes, act as a passive load during the depolarization phase. Using theoretical arguments and numerical simulations in a tissue incorporating fibroblasts, the passive load approximation is shown to be accurate at low coupling conductances (< 2 nS). In this case, the effect on conduction velocity can be expressed as a function of the elevation in resting potential and the coupling only.