Panel A: Representative time-course traces showing mito-iATP fluorescence transients in the superior SA node. Panel B: Representative time-course traces showing mito-iATP fluorescence transients in the inferior SA node. Panel C: Scatter plot quantifying time to mito-iATP peak for superior and inferior SA nodes. Panel D: Scatter plot quantifying mito-iATP decay t 1/2 for superior and inferior SA nodes. Panel E: Scatter plot quantifying mito-iATP transient duration for superior and inferior SA nodes. Panel F: Representative time-course traces showing mito-iATP fluorescence transients in the superior SA node. Panel G: Representative time-course traces showing mito-iATP fluorescence transients in the inferior SA node. Panel H: Scatter plot quantifying time to mito-iATP peak for superior and inferior SA nodes. Panel I: Scatter plot quantifying mito-iATP decay t 1/2 for superior and inferior SA nodes. Panel J: Scatter plot quantifying mito-iATP transient duration for superior and inferior SA nodes. Each panel includes data points for individual biological replicates and per-animal means.
Mitochondrial ATP synthesis kinetics is regionally conserved, whereas consumption duration scales with metabolic load. (A–E) Kinetic analysis of Mode 1 (ATP production) mito-iATP transients. (A and B) Representative time course traces from superior (A) and inferior (B) SA node regions. Traces are normalized to peak amplitude to facilitate comparison of temporal kinetics. The dashed line indicates baseline fluorescence (F/F0 = 1). (C–E) Summary quantification of time to peak (C), decay t1/2 (D), and transient duration (E) (N = 6 mice per group). (F–J) Kinetic analysis of Mode 2 (ATP consumption) mito-iATP transients. (F and G) Representative time course traces from superior (F) and inferior (G) SA node regions showing negative mito-iATP deflections associated with ATP consumption. (H–J) Summary quantification of time to peak (H), decay t1/2 (I), and transient duration (J). P values are shown above comparisons. Large circles denote per-animal means; small circles indicate individual biological replicates. N represents the number of independent mice.