[Ca ²⁺ ] profiles in the cytoplasm (left panels) and LSR (right panels) compared with locations of sparks and embers (middle panels). The cell long axis of symmetry (i.e., the cell center) is at x = y = 0. The z-t fluorescent line scan for this Ca²⁺ wave is shown in Fig. 6 A using the same time reference. Blue dots indicate locations of sparks, and red dots indicate embers (Ca²⁺ release events with duration >50 ms). The upper panels show the x-y plane indicated by the dotted line in the lower panels, and the lower-left panels show the x–z plane indicated by that in the upper-left panels. Release events along the z axis are shown throughout the entire cell volume and are viewed 1° rotated from the y-direction to avoid obscuring release sites.