Figure 7. Ageing increases SR Ca²⁺ leak, which is reversed with mitochondrial ROS scavenging with mito-TEMPO.

A, representative F F₀⁻¹ time-dependent profiles of cell-averaged luminal Fluo-5N signals from intact cardiomyocytes from young and old rabbits as well as from cardiomyocytes from old rabbits pretreated with mito-TEMPO (MT, 25 μm) for 10 min, and from cardiomyocytes from young rabbits in the presence of 250 μm caffeine. Fluorescence signal was normalized to the minimum fluorescence with 10 mm caffeine. B, mean time constants (τ) from exponential fit of SR Ca²⁺ leak from intact cardiomyocytes: young, 481.98 ± 61.23; old, 246.31 ± 26.75; old + MT, 575.05 ± 35.52; and young + caffeine, 293.49 ± 34.98 s. *P < 0.05 for young vs. young + caffeine. **P < 0.01 for young vs. old and old + MT vs. young + caffeine. ***P < 0.001 for old vs. old + MT. n = 9–16 cells from 2 heart preparations; all values are mean ± SEM.