Ca²⁺ fluxes and concentrations during a Ca²⁺ wave. (A–C) Ca²⁺ release in the x-y planes at z= 46 μm (A and C) near where the Ca²⁺ wave initiates and z= 21 μm (B) near the z midpoint. Ca²⁺ release was simulated under the same conditions as used in Fig. 6 A. Upper panels show the time course of cytoplasmic [Ca²⁺] averaged over the x-y plane. Lower panels show the corresponding mean LSR [Ca²⁺] (green) and the total Ca²⁺ fluxes through all 371 dyads in the x-y plane originating from the initial flux transients from sparks and embers (red) or the subsequent flux plateaus from embers (blue). (C) Identical to A except that after the 3-s time point, the plateau phase of embers is suppressed (i.e., they become sparks) by a threefold decrease in diffusion across the LSR/TSR nexus. The horizontal bars in A and B indicate the period where the cytoplasm is being primed for CICR.