Efficient and detailed model of the local Ca2+ release unit in the ventricular cardiac myocyte.

We present here an efficient but detailed approach to modelling Ca(2+)-induced Ca(2+) release in the diadic cleft of cardiac ventricular myocytes. In this Framework we developed a spatial resolved Ca(2+) release unit (CaRU), consisting of the junctional sarcoplasmic reticulum and the diadic cleft, with a well defined channel placement. By taking advantage of time scale separation, the model could be finally reduced to only one ordinary differential equation for describing Ca(2+) fluxes and diffusion. Additionally the channel gating is described in a stochastic way. The resulting model is able to reproduce experimental findings like the gradedness of SR release, the voltage dependence of ECC gain and typical spark life time. Due to the numerical efficiency of the model, it is suitable to use for whole cell simulations. The approach we want to use extend the developed (CaRU) to such a whole cell model is already outlined in this work.