title: Computational modeling and numerical methods for spatiotemporal calcium cycling in ventricular myocytes.
abstract: Intracellular calcium (Ca) cycling dynamics in cardiac myocytes is regulated by a complex network of spatially distributed organelles, such as sarcoplasmic reticulum (SR), mitochondria, and myofibrils. In this study, we present a mathematical model of intracellular Ca cycling and numerical and computational methods for computer simulations. The model consists of a coupled Ca release unit (CRU) network, which includes a SR domain and a myoplasm domain. Each CRU contains 10 L-type Ca channels and 100 ryanodine receptor channels, with individual channels simulated stochastically using a variant of Gillespie's method, modified here to handle time-dependent transition rates. Both the SR domain and the myoplasm domain in each CRU are modeled by 5 × 5 × 5 voxels to maintain proper Ca diffusion. Advanced numerical algorithms implemented on graphical processing units were used for fast computational simulations. For a myocyte containing 100 × 20 × 10 CRUs, a 1-s heart time simulation takes about 10 min of machine time on a single NVIDIA Tesla C2050. Examples of simulated Ca cycling dynamics, such as Ca sparks, Ca waves, and Ca alternans, are shown.
authors.affiliation: Department of Medicine (Cardiology), David Geffen School of Medicine University of California Los Angeles, CA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Nivala
authors.forename: Enno
authors.initials: E
authors.lastname: de Lange
authors.forename: Robert
authors.initials: R
authors.lastname: Rovetti
authors.forename: Zhilin
authors.initials: Z
authors.lastname: Qu