Figure 10. Mitochondrial ROS scavenger mito-TEMPO reverses the effects of ageing with regard to refractoriness of RyR-mediated Ca²⁺ release under β-adrenergic stimulation.

A, confocal line scan images and Fluo-3 F F₀⁻¹ profiles at the end of 1 min 1 Hz pacing train with cardiomyocytes from young and old rabbits and from cardiomyocytes pretreated with mito-TEMPO (25 μm) for 10 min from old rabbits with 30 nm ISO. Spontaneous Ca²⁺ waves (SCWs) are indicated by an asterisk. B, mean data for percentage of cells exhibiting SCWs: young, 33.33 ± 8.75; old, 73.68 ± 10.38; old + MT, 26.93 ± 8.87, and young + caffeine 66.67%. *P < 0.05 for young vs. old, **P < 0.01 for old vs. old + MT. n= 9–30 cells from 2–4 heart preparations. C, mean data for SCW latency: young, 6.94 ± 1.58; old, 1.88 ± 0.34; old + MT, 9.11 ± 3.15, and young + caffeine, 1.20 ± 0.28 s. *P < 0.05 for young vs. old and old + MT vs. young + caffeine. **P < 0.01 for old vs. old + MT. n= 6–14 cells from 2–4 heart preparations. All values are mean ± SEM.