Combining stochastic and deterministic methods to simulate local control by diadic Ca2+ during a ventricular action potential

To study the impact of local Ca2+ control in the context of the whole cell AP, we have now developed a new 'hybrid' class of ventricular cell model which combines the stochastic simulation of a large number of independent FRUs with the deterministic integration of a system of coupled ordinary differential equations describing the full complement of cardiac membrane currents and intracellular fluxes. Implementation of the model, and its application to study the effects of determinants of FRU recruitment and gain, such as diadic volume and ICaL channel to RyR ratio, on AP and whole cell Ca2+ cycling, will be presented.