Fig. 5.

Effect of acute introduction of single RyR2 activation changes on alternans. Release duration (A), diastolic Ca²⁺ concentration in the subspace (B), SR Ca²⁺ release integral (C), SR Ca²⁺ uptake integral (D), maximal NSR Ca²⁺ content (E), and fractional JSR emptying (F) are shown as a function of the AP index after stabilization (APs of 2,437–2,480 are shown from a sequence of 2,500 APs, with RyR2 activation from an AP index of 0, corresponding to an AP of 2,440). The model was paced at a BCL of 260 ms under control conditions or with selective changes to RyR2 time constants (τ), RyR2 amplitude of SR Ca²⁺ release (Amp), or JSR Ca²⁺ leak.