Figure 10. Panel A: Representative... | Rockefeller University Press

Figure 10.

Beat-to-beat mitochondrial ATP consumption 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 Mode 2 mitochondrial ATP signals (mito-iATP; green, bottom). The dashed line indicates baseline fluorescence (F/F0 = 1). (A) Example of a myocyte classified as high-load, in which Ca2+ release is associated with large-amplitude negative mito-iATP deflections. (B) Example of a myocyte classified as low-load, showing Ca2+ transients with smaller accompanying mito-iATP deflections. (C) Event-level relationship between Ca2+ signal mass (input) and mitochondrial ATP consumption signal mass (output). Data are segregated into two populations: high-load events (blue circles) and low-load events (orange circles). Solid lines indicate linear fits for each population. (D) Cell-averaged relationship between Ca2+ signal mass and mitochondrial ATP consumption for high-load (blue) and low-load (orange) groups. Scale bars, 5 µm. Data are presented as mean fits (N = 4 mice per group). In C, circles represent individual biological events; in D, circles denote per-animal means. N represents the number of independent mice. Refer to the image caption for details.

Panel A: Representative confocal line-scan recordings showing high mitochondrial ATP consumption with large negative deflections in response to calcium transients. Panel B: Representative confocal line-scan recordings showing low mitochondrial ATP consumption with smaller deflections in response to calcium transients. Panel C: Scatter plot with calcium signal mass on the horizontal axis and mitochondrial ATP consumption signal mass on the vertical axis. Data points are segregated into high-load events (blue circles) and low-load events (orange circles). Solid lines indicate linear fits for each population. Panel D: Scatter plot showing cell-averaged relationship between calcium signal mass and mitochondrial ATP consumption for high-load (blue circles) and low-load (orange circles) groups.

Beat-to-beat mitochondrial ATP consumption 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 Mode 2 mitochondrial ATP signals (mito-iATP; green, bottom). The dashed line indicates baseline fluorescence (F/F₀ = 1). (A) Example of a myocyte classified as high-load, in which Ca²⁺ release is associated with large-amplitude negative mito-iATP deflections. (B) Example of a myocyte classified as low-load, showing Ca²⁺ transients with smaller accompanying mito-iATP deflections. (C) Event-level relationship between Ca²⁺ signal mass (input) and mitochondrial ATP consumption signal mass (output). Data are segregated into two populations: high-load events (blue circles) and low-load events (orange circles). Solid lines indicate linear fits for each population. (D) Cell-averaged relationship between Ca²⁺ signal mass and mitochondrial ATP consumption for high-load (blue) and low-load (orange) groups. Scale bars, 5 µm. Data are presented as mean fits (N = 4 mice per group). In C, circles represent individual biological events; in D, circles denote per-animal means. N represents the number of independent mice.