Simulation Study of Electrotonic Coupling between Human Atrial Myocytes and Mechanosensitive Fibroblasts

This study aimed to investigate the effect on adjacent myocyte of fibroblasts (Fbs) with the incorporation of mechano-gated currents induced by mechanical compression (I-ci) of cardiac Fbs. The human atrial myocyte (hAM) was modeled by the Courtemanche-Ramirez-Nattel model. With two different experimentally observed Fbs compression (2 mu m and 3 mu m), I-ci was numerically simulated as I-cil and I-cih. They were then incorporated into two types of electrophysiological models of human atrial Fbs: passive and active models, respectively. In both passive and active models, I-ci depolarized the membrane potential of cardiac Fbs. When coupled with passive Fbs, the action potential of myocyte duration at 90% (APD(90)) was increased in comparison with uncoupled hAM With the incorporation of I-ci into passive Fbs, APD(90) of myocyte was further increased. When coupled with active Fbs, similar increases were obtained with the incorporation of both I-ci Furthermore, the resting potential and the maximum value of the action potential of hAM were also increased for both models and with both I-ci. The preliminary simulation study confirmed that mechanosentitive currents in fibroblasts play an important role in mechano-electrical coupling.