Effects of Acute Exercise on Mitochondrial Function, Dynamics, and Mitophagy in Rat Cardiac and Skeletal Muscles

This study aimed to investigate the effects of single-bout exercise on mitochondrial function, dynamics (fusion, fission), and mitophagy in cardiac and skeletal muscles.

Fischer 344 rats (4 months old) were randomly divided into the control (CON) or acute exercise (EX) group (n=10 each). The rats performed a single bout of treadmill exercise for 60 minutes. Mitochondrial function (e.g., O2 respiration, H2O2 emission, Ca2+ retention capacity), mitochondrial fusion (e.g., Mfn1, Mfn2, Opa1), mitochondrial fission (e.g., Drp1, Fis1), and mitophagy (e.g., Parkin, Pink1, LC3II, Bnip3) were measured in permeabilized cardiac (e.g., left ventricle) and skeletal (e.g., soleus, white gastrocnemius) muscles.

Mitochondrial O2 respiration and Ca2+ retention capacity were significantly increased in all tissues of the EX group compared with the CON group. Mitochondrial H2O2 emissions showed tissue-specific results; the emissions showed no significant differences in the left ventricle or soleus (type I fibers) but was significantly increased in the white gastrocnemius (type II fibers) after acute exercise. Mitochondrial fusion and fission were not altered in any tissues of the EX group. Mitophagy showed tissue-specific differences: It was not changed in the left ventricle or white gastrocnemius, whereas Parkin and LC3II were significantly elevated in the soleus muscle.

A single bout of aerobic exercise may improve mitochondrial function (e.g., O2 respiration and Ca2+ retention capacity) in the heart and skeletal muscles without changes in mitochondrial dynamics or mitophagy.