Fig. 9.

Spark score as a function of the rate of myoplasmic domain collapse (v_myo^T) and SR domain recovery (v_sr^T). Robust sparks correspond to a score of >0.2. *Standard parameters. A: in the minimal whole cell model of quiescent ventricular myocytes, bulk SR [Ca²⁺] is an increasing function of v_myo^T and a decreasing function of v_sr^T (Fig. 8A) and sparks were observed for a wide range of values of the rate constants. B: when these calculations were repeated with bulk myoplasmic and SR [Ca²⁺] fixed at baseline values (c_myo = 0.1 μM and c_sr = 342 μM), the range of domain rate constants leading robust sparks was much smaller.