Fig. 5: Mitochondrial bioenergetic activity is decreased in sarcopenic muscle.

a Schematic representation of a mitochondrion and the five respiratory complexes of the electron transport chain. b Gene expression change in sarcopenic vs. control muscle of mRNAs encoding the subunits of the 5 mitochondrial respiratory chain complexes, color coded according to moderated t-statistics (SSS cohort; n = 19–20 per group). c, d Muscle protein expression of representative subunits of mitochondrial respiratory chain complexes and mitochondrial proteins measured by western blot. c Representative blots from one gel, with GAPDH and HSC70 included as house-keeping normalization controls. d Quantification of protein levels relative to GAPDH and HSC70 in all remaining samples analyzed (SSS cohort; n = 15–16 per group; p values calculated using Mann–Whitney tests). e Enzymatic activity per mg muscle tissue of mitochondrial complexes I–IV, citrate synthase (CS) and succinate dehydrogenase (SDH) measured on mitochondrial extracts from remaining muscle biopsies of control and sarcopenic participants (SSS cohort; n = 18 per group; p values calculated with Mann–Whitney tests). f, g Muscle protein expression of porin 1 and CS measured by western blot on remaining muscle samples of the SSS cohort (n = 20 per group; p values calculated with Mann–Whitney tests).