Intercellular coupling mediated by potassium accumulation in peg-and-socket junctions

Coupling of smooth muscle cells is important for coordination of gastrointestinal motility. Small structures called peg-and-socket junctions (PSJs) have been found between muscle cells and may play a role in electrical coupling due to extracellular potassium accumulation in the narrow cleft between the muscle cells. A model was developed in which an electrical boundary element model of the cell morphology is used in conjunction with a finite difference model which described ionic fluxes and diffusion of extracellular potassium in the PSJ. The boundary element model used a combination of triangular and cylindrical elements to reduce computational demand while ensuring accuracy. Barrier kinetics were used to model the underlying ionic transport mechanisms. Seven ionic transport mechanisms were used to create the transmembrane voltage waveform. Results indicate that PSJs may produce significant coupling between smooth muscle cells under appropriate conditions. Coupling increased exponentially with increasing length and with decreasing intercellular gap.