Fig. 1: Respiratory reserve (Rres) in isolated cardiomyocytes from HCR and LCR as a function of substrate and age.
a Rres, defined as the difference between the oxygen consumption rate (OCR) OCRFCCP minus the OCRsubstr (inset; see also Supplementary Fig. 1), was quantified in ventricular cardiomyocytes isolated from HCR or LCR rats at the indicated ages (6, 17, or 24 months old). Cardiomyocytes were assayed in the presence of 5 mM glucose or 0.2 mM palmitate bound to fatty acid-free bovine serum albumin, 4 : 1, or the combination of both substrates added in the first part of the assay (marked as substrate in the inset) before subsequent additions as described in “Cardiomyocytes isolation and high-throughput respiratory measurements” in “Methods”. See related Supplementary Fig. 1 for OCR measurements, full experimental design, experiments/n-values, and Supplementary Figs 2 and 3 for additional two-way ANOVA with Tukey’s multiple comparison test (GraphPad Prism 8.0) and all data points. b OCR-oligomycin sensitive obtained with mitochondria isolated from the hearts of 6-month-old HS (3 rats/experiments, n = 62), LCR (4 rats/experiments, n = 85), or HCR (4 rats/experiments, n = 90) rats, and assayed in the presence of glutamate/malate (G/M) or palmitoyl CoA (PCoA)/malate as detailed in “Methods”. See related Supplementary Fig. 5 including all data points. The statistical analysis corresponds to one-way ANOVA with Tukey’s multiple comparison test (GraphPad Prism 8.0). c Rres of cardiomyocytes isolated from 6-month-old HS (3 rats/experiments, n = 66–72), LCR (4 rats/experiments, n = 37–47), or HCR (4 rats/experiments, n = 37–48) rats, as indicated in the presence of glucose or palmitate or their combination (see “Methods” for details and related Supplementary Fig. 6). Two-way ANOVA analysis with Tukey’s multiple comparison test was performed with GraphPad Prism 8.0 using substrate and strain as factors. d Autophagy in cardiomyocytes isolated from 6-month-old HS (3 rats/experiments, n = 78), LCR (4 rats/experiments, n = 52), or HCR (4 rats/experiments, n = 53) rats (see “Methods” for details and related Supplementary Fig. 7a, which, in addition, shows measurements of tmPTP (Supplementary Fig. 7b) and lipofuscin (Supplementary Fig. 7c). The statistical analysis corresponds to one-way ANOVA with Tukey’s multiple comparison test (GraphPad Prism 8.0). In all cases, data are represented as mean ± SEM and the statistical significance is indicated by *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; NS not significant. FCCP Trifluoromethoxy carbonylcyanide phenylhydrazone.
