Research Paper Volume 10, Issue 11 pp 3327—3352

Oxidative muscles have better mitochondrial homeostasis than glycolytic muscles throughout life and maintain mitochondrial function during aging

Figure 1. In young mice, the soleus is more oxidative than the tibialis anterior, and expresses higher levels of mitochondrial biogenesis, fission/fusion and autophagy markers. Markers of oxidative metabolism, mitochondrial biogenesis, fission/fusion and autophagy were evaluated in tibialis anterior and soleus muscles from young (3 mo) mice. (A-B) Myoglobin and representative electron transport chain enzymes (OXPHOS) in whole muscle lysates were assessed by Western blotting and normalized to Ponceau-stained total protein (see Figure S1). The mean plus standard deviation of 3 technical replicates of lysates from 5 mice/group is shown. (C-D) Succinate dehydrogenase (SDH i.e. OXPHOS Complex II) activity was assessed by histochemical staining. Representative images are shown (C; tibialis anterior scale bar = 400 µm, soleus scale bar = 200 µm) and the SDH activity of the entire muscle sections (indicated by the red dotted lines i.e. the EDL and gastrocnemius were excluded) was evaluated by assessing pixel intensities (D; mean plus standard deviation of 3 mice/group, 2 sections per mouse). (E) PGC-1α, PGC-1β, Mfn2, short (S)- and long (L)-OPA1, LC3-II/I and APG5 in whole muscle lysates were evaluated by Western blotting and normalized to Ponceau-stained total protein (see Figure S1). The mean plus standard deviation of 3 technical replicates of lysates from 5 mice/group is shown. (F) Mfn2 and OPA1 in mitochondrial fractions were evaluated by Western blotting and normalized to Ponceau-stained total protein (see Figure S1). The mean plus standard deviation of lysates from 4 mice/group is shown. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001.