Fig. 1.

Illustration of the spatial distribution of ion channels and compartments involved in intracellular Ca cycling. The Ca concentrations in the dyadic junction, the submembrane space, the local cytosol, the junctional sarcoplasmic reticulum (JSR) space, and the network SR (NSR) space are denoted as c_p^k, c_s^k, c_i^k, c_jsr^k, and c_sr^k, respectively, where the superscript k denotes the k^th Ca-release unit (CRU). Each cell is modeled in an array of diffusively coupled CRUs. RyR, Ryanodine receptor.