Figure 9. Panel A: Line-scan recordings... | Rockefeller University Press

Figure 9.

Beat-to-beat mitochondrial ATP synthesis exhibits bimodal coupling to intracellular Ca2+release in SA node myocytes. (A and B) Representative confocal line-scan recordings showing simultaneous intracellular Ca2+ transients (red, top) and mitochondrial ATP signals (mito-iATP; green, bottom). The dashed line indicates baseline fluorescence (F/F0 = 1). (A) Example of a myocyte classified as high-gain, displaying temporally aligned Ca2+ transients and mito-iATP signals. (B) Example of a myocyte classified as low-gain, in which Ca2+ transients are accompanied by minimal mito-iATP responses. (C) Event-level relationship between Ca2+ signal mass (input) and mito-iATP signal mass (output). Data are segregated into two populations: high-gain events (blue circles) and low-gain events (orange circles), with solid lines indicating linear fits. (D) Cell-averaged relationship between Ca2+ and mito-iATP signal mass, fitted with a Hill function for each group (high-gain, blue; low-gain, orange). (E and F) Summary quantification of Ca2+ signal mass rate (E) and mito-iATP signal mass rate (F) for high- and low-gain populations. P values are shown above comparisons. Data are presented as means ± SEM (N = 4 mice per group). Large circles denote per-animal means; small circles indicate individual biological replicates. N represents the number of independent mice. Refer to the image caption for details.

Panel A: Line-scan recordings of a high-gain myocyte showing temporally aligned calcium transients and mitochondrial ATP signals. Panel B: Line-scan recordings of a low-gain myocyte showing calcium transients with minimal mitochondrial ATP responses. Panel C: Scatter plot showing the relationship between calcium signal mass and mitochondrial ATP signal mass, with high-gain events in blue and low-gain events in orange. Panel D: Scatter plot showing the cell-averaged relationship between calcium and mitochondrial ATP signal mass, fitted with a Hill function for each group. Panel E: Quantification of calcium signal mass rate for high-gain and low-gain populations. Panel F: Quantification of mitochondrial ATP signal mass rate for high-gain and low-gain populations.

Beat-to-beat mitochondrial ATP synthesis exhibits bimodal coupling to intracellular Ca ²⁺ release in SA node myocytes. (A and B) Representative confocal line-scan recordings showing simultaneous intracellular Ca²⁺ transients (red, top) and mitochondrial ATP signals (mito-iATP; green, bottom). The dashed line indicates baseline fluorescence (F/F₀ = 1). (A) Example of a myocyte classified as high-gain, displaying temporally aligned Ca²⁺ transients and mito-iATP signals. (B) Example of a myocyte classified as low-gain, in which Ca²⁺ transients are accompanied by minimal mito-iATP responses. (C) Event-level relationship between Ca²⁺ signal mass (input) and mito-iATP signal mass (output). Data are segregated into two populations: high-gain events (blue circles) and low-gain events (orange circles), with solid lines indicating linear fits. (D) Cell-averaged relationship between Ca²⁺ and mito-iATP signal mass, fitted with a Hill function for each group (high-gain, blue; low-gain, orange). (E and F) Summary quantification of Ca²⁺ signal mass rate (E) and mito-iATP signal mass rate (F) for high- and low-gain populations. P values are shown above comparisons. Data are presented as means ± SEM (N = 4 mice per group). Large circles denote per-animal means; small circles indicate individual biological replicates. N represents the number of independent mice.