Figure 5.

Confocal imaging of spontaneous Ca²⁺ release events at GFP-RyR2 clusters in the interior and periphery within the same ventricular myocytes. High-speed confocal imaging of spontaneous Ca²⁺ release (red fluorescence) at GFP-RyR2 clusters (green puncta) at the interior and peripheral confocal focus planes of the same ventricular myocyte is presented in (A). Distribution of GFP-RyR2 clusters in the interior was found to be highly ordered, contrasting irregular patterns at the periphery (GFP-RyR2). Ca²⁺ sparks were detected at GFP-RyR2 locations as spatiotemporally restricted small increases in Rhod-2 fluorescence intensity. 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; (n = 16 cells; 927 Ca²⁺ spark events in interior and 774 Ca²⁺ spark events in the periphery; f, frame) is shown in (B). To see this figure in color, go online.