Figure 4.

Dynamics of diastolic Ca²⁺ spark triggering and termination. (A) Spontaneous RyR Ca²⁺ current in pA during a 1-s simulation. (B) Zoom of RyR current showing spark initiation and termination profiles. (Colored lines) Different CRUs, respectively, where a Ca²⁺ spark is observed. (Shading) Nonspark RyR activity for the remaining CRUs. Note: For visual clarity, only 10% of the whole cell activity is displayed here. (C) Number of Ca²⁺ sparks as function of the strength of allosteric coupling (coupling strength is assumed to be symmetrical, i.e., ε_∗ = ε_cc = ε_oo). (D) Average Ca²⁺ spark duration versus ε_∗.