Modeling of heterogeneity in electrical and mechanical properties of guinea pig ventricular myocytes

Heterogeneity of myocardium proved to be important for understanding heart physiology and pathophysiology. In contrast to a number of papers addressing the electrophysiological heterogeneity of cardiomyocytes, much less is known about heterogeneity of their mechanical function. The aim of this study was to develop mathematical models of the electrical and mechanical function of cardiomyocytes from sub-epi- and sub-endocardial ventricular layers that take into account specific features of intracellular mechanisms underlying pronounced regional differences in the functional properties of the cells in guinea pig. Using the developed models we quantitatively tested several hypotheses on possible contribution of the transmural gradient in Na⁺/Ca²⁺ exchange currents to the cellular function. The simulations consist with a hypothesis that transmural gradient in Na⁺/Ca²⁺ exchange currents may partially result from the heterogeneity in Na⁺/K⁺ pump in cells from different transmural regions.