Influence of Dynamic Gap Junction Resistance on Impulse Propagation in Ventricular Myocardium: A Computer Simulation Study

Abstract

The gap junction connecting cardiac myocytes is voltage and time dependent. This simulation study investigated the effects of dynamic gap junctions on both the shape and conduction velocity of a propagating action potential. The dynamic gap junction model is based on that described by Vogel and Weingart (J. Physiol. (Lond.). 1998, 510:177-189) for the voltage- and time-dependent conductance changes measured in cell pairs. The model assumes that the conductive gap junction channels have four conformational states. The gap junction model was used to couple 300 cells in a linear strand with membrane dynamics of the cells defined by the Luo-Rudy I model. The results show that, when the cells are tightly coupled (6700 channels), little change occurs in the gap junction resistance during propagation. Thus, for tight coupling, there are negligible differences in the waveshape and propagation velocity when comparing the dynamic and static gap junction representations. For poor coupling (85 channels), the gap junction resistance increases 33 MOmega during propagation. This transient change in resistance resulted in increased transjunctional conduction delays, changes in action potential upstroke, and block of conduction at a lower junction resting resistance relative to a static gap junction model. The results suggest that the dynamics of the gap junction enhance cellular decoupling as a possible protective mechanism of isolating injured cells from their neighbors.

Fast calcium wave propagation mediated by electrically conducted excitation and boosted by CICR

“…12,19,20,43). In our study, we ignore coupling of oscillations by calcium and IP 3 diffusion for good reasons, which are explained in the DISCUS-SION.On the other hand, there is propagation of electrical activity in networks of cells electrically coupled by gap junctions, such as in the ventricular myocardium (17,18,(23)(24)(25)(26). In such types of cell networks, propagation of electrical activity is the result of depolarization of a cell by action potential (AP) firing of its neighbor.…”

Dynamics of sustained reentry in a loop model with discrete gap junction resistances

“…Whether alternative approaches that have been proposed for the continuous loop would be more appropriate remains to be determined. [11,16,17] In any case, we are still far from a general low-dimensional model that could be applied in situations including a dynamic change of the intercellular coupling, as in [28,29,30].…”

Early afterdepolarisations and ventricular arrhythmias in cardiac tissue: a computational study

“…Previous computational studies have indicated that the number of cells producing abnormal electrical activity is critical in determining whether a propagating extrasystole will be generated [20]. This idea is similar to the concept of liminal length in neuronal propagation.…”