Results of a simulation like that in Fig. 7 except that the modeled troponin reaction included competition between Mg²⁺ and Ca²⁺ (see Fig. 3). In each panel (A, faster time base; B, slower time base), the superimposed traces at the top show simulated changes in the spatially averaged concentration of the doubly occupied Ca²⁺–troponin state (rightmost state in Fig. 3), which were averaged over the nine troponin-containing compartments (see Fig. 2). The continuous trace is from this simulation; the broken trace is from the simulation of Fig. 7. For this simulation, the release amounts, τ1, and τ2 are 284 µM, 1.5 ms, and 0.65 ms (first component); and 90 µM, 1.7 ms, and 7 ms, respectively (second component). The peak value, time of peak, and FDHM of the composite release waveform are 133 µM/ms, 2.7 ms, and 2.0 ms.