Multiscale Modeling of Calcium Dynamics in Ventricular Myocytes With Realistic Transverse Tubules

Spatial-temporal Ca²⁺ dynamics due to Ca²⁺ release, buffering, and reuptaking plays a central role in studying excitation-contraction (E-C) coupling in both normal and diseased cardiac myocytes. In this paper, we employ two numerical methods, namely, the meshless method and the finite element method, to model such Ca²⁺ behaviors by solving a nonlinear system of reaction-diffusion partial differential equations at two scales. In particular, a subcellular model containing several realistic transverse tubules (or t-tubules) is investigated and assumed to reside at different locations relative to the cell membrane. To this end, the Ca²⁺ concentration calculated from the whole-cell modeling is adopted as part of the boundary constraint in the subcellular model. The preliminary simulations show that Ca²⁺ concentration changes in ventricular myocytes are mainly influenced by calcium release from t-tubules.