Functional heterogeneity arising due to electrical and mechanical interactions between cardial myocytes in mathematical model of homogeneous myocardial fiber

We developed a mathematical model describing heart muscle strand as a one-dimensional continuous medium of cardiomyocytes, through which electrical excitation propagates and excites the cells for contraction. Intracellular excitationcontraction coupling is presented by means of our earlier published model describing mechanical function of the cardiomyocyte evoked by action potential development and calcium activation of cross-bridge formation. The whole strand model simulates also mechanical interaction between the cardiomyocytes in the tissue and accounts for both intracellular and intercellular electro-mechanical coupling and mechano-electric feedback mechanisms. Numerical experiments with the strand formed of initially identical cardiomyocytes revealed that electrical and mechanical interaction between the cells, as well as intracellular mechano-electric feedbacks caused pronounced nonuniformity of their behavior. Model analysis suggests that cooperative mechanisms of myofilament calcium activation play the key role in dynamic adjustment of electrical and mechanical activity of the interacting cardiomyocytes in the tissue.