Resistance and potential profiles in the cleft between two myocardial cells: Electrical analog and computer simulations

Abstract

The electrical properties of the intercalated disk cleft between cardiac muscle cells have been modeled by a discrete three-dimensional analog model. The model was analyzed both theoretically and experimentally to determine the voltage at the various nodes and the resistance from the nodes to ground (mouth of the cleft). The results are similar to those based on theoretical solutions of a continuous model. The underlying assumptions and the results from several theoretical models in the literature were compared. It was found that the potential profile was bullet-shaped, the potential being maximum in the center of the cleft and zero at the edges. The resistance profile was similar in shape, but the profile was flatter, the resistance changing most sharply at the edges. These results indicate that current entering the cleft from the prejunctional cell, nearly uniformly distributed across the area of the prejunctional membranes, will produce a large voltage in the middle regions of the cleft. Therefore, this cleft potential will change the potential across the postjunctional membrane, and thereby alter its state of excitability.