Fig. 3: Confocal live fluorescence imaging of mitochondrial fitness and lipofuscin in LCR and HCR cardiomyocytes during aging.
a mPTP-ROS threshold (tmPTP) as index of mitochondrial fitness was quantified in isolated TMRM-loaded cardiomyocytes from 6 (LCR: 4 rats/experiments, n = 47; HCR: 4 rats/experiments, n = 46), 17- (LCR: 4 rats/experiments, n = 44; HCR: 5 rats/experiments, n = 44), and 24 (LCR: 5 rats/experiments, n = 79; HCR: 7 rats/experiments, n = 91) months old rats, using high-resolution confocal fluorescent microscopy. tmPTP reflects the average time required for the photoproduced ROS to cause mPTP opening induction. b Representative example of tmPTP determination in LCR vs. HCR cardiomyocytes. c Lipofuscin quantification as % cell area covered by progressive age-dependent accumulation of lipofuscin as revealed by autofluorescence of cardiomyocytes from 6 (LCR: 3 rats/experiments, n = 55; HCR: rats/experiments, n = 56), 17 (LCR: 2 rats/experiments, n = 33; HCR: 2 rats/experiments, n = 34), and 24 (LCR: 5 rats/experiments, n = 80; HCR: 5 rats/experiments, n = 97) months old rats. d Zoomed image showing, in detail, accumulated lipofuscin as visualized by autofluorescence (blue) and TMRM-loaded mitochondria (red), and e representative examples of cardiomyocytes, full-scale, at 6 and 24 months of age. In all cases, data are represented as mean ± SEM. The statistical significance is indicated by *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; NS not significant.
