On the Cardiac Gap Junctions Channel Modeling

Cardiac signaling is mediated by gap junction channels between cardiac cells called cardiomyocytes. Each gap junction channel is made of hundreds of single channels, with each channel consisting of two hemichannels. The hemichannels in cardiomyocytes are made of connexins -- Cx40, Cx43 and Cx45 proteins. The permeability of hemichannels depends on the changes in the transjunctional voltages and membrane potentials, and their morphological properties expressed through connexin combinations. Although these dependencies are known to a considerable extent, their simultaneous effect on the total gap junction behavior is not completely addressed in the available models. Here we propose a channel model that integrates the aforementioned dependencies. We weight the total gap junction conductance according to the topographical distribution of connexins in different heart tissues based on real data. Moreover, we add a mathematical formulation of the membrane potential gating phenomenon to the basic gap junction conductance model. The proposed model covers most of the known conductance properties of gap junction channels in a computationally efficient way and potentially plays an important role in addressing communication-theoretic problems related to gap junctions in the future.