Figure 6.

TIRF and HILO imaging of spontaneous Ca²⁺ release events at GFP-RyR2 clusters in the interior and periphery within the same ventricular myocytes. Spontaneous Ca²⁺ release at GFP-RyR2 clusters was recorded in the interior and periphery of the same ventricular myocyte with a TIRF microscope. Images from the time series (50–60 FPS) of GFP-RyR2 clusters were observed as stationary fluorescence peaks throughout the recording, as displayed. Their distribution appeared highly ordered in the interior and disordered in the periphery of the same cell (A). Ca²⁺ sparks appeared clearly at GFP-RyR2 clusters as transient and spatially restricted elevations in fluorescence signals (A). Quantitative comparison of characteristics of elementary Ca²⁺ release at RyR2 clusters (a) amplitude; (b) rate-of-rise; (c) duration at half maximum; and (d) decay time are shown (n = 10 cells; 1872 Ca²⁺ sparks in interior and 4153 Ca²⁺ sparks in periphery; f, frame) is shown in (B). To see this figure in color, go online.