Skeletal muscle autophagy and mitophagy in endurance-trained runners before and after a high-fat meal

• Published in: Molecular metabolism (Germany) Vol. 6; no. 12; pp. 1597 - 1609
• Main Authors: Tarpey, Michael D, Davy, Kevin P, McMillan, Ryan P, Bowser, Suzanne M, Halliday, Tanya M, Boutagy, Nabil E, Davy, Brenda M, Frisard, Madlyn I, Hulver, Matthew W
• Format: Journal Article
• Language: English
• Published: Germany Elsevier 01.12.2017
• Subjects: Adolescent; Adult; Autophagy; Case-Control Studies; Diet, High-Fat; Dietary Fats - metabolism; Endurance Training; Fasting - metabolism; Humans; Male; Mitochondrial Degradation; Muscle, Skeletal - metabolism; Original; Oxygen Consumption; Running - physiology; Endurance training; Mitophagy; Autophagy; Metabolic flexibility; Skeletal muscle
• ISSN: 2212-8778; 2212-8778
• DOI: 10.1016/j.molmet.2017.10.006

We tested the hypothesis that skeletal muscle of endurance-trained male runners would exhibit elevated autophagy and mitophagy markers, which would be associated with greater metabolic flexibility following a high-fat meal (HFM). Muscle biopsies were collected to determine differences in autophagy and mitophagy protein markers and metabolic flexibility under fasting conditions and 4 h following a HFM between endurance-trained male runners (n = 10) and sedentary, non-obese controls (n = 9). Maximal oxygen consumption (ml·kg·min ) was approximately 50% higher (p < 0.05) in endurance-trained runners compared with sedentary controls (65.8 ± 2.3 and 43.1 ± 3.4, respectively). Autophagy markers were similar between groups. Mitophagy and mitochondrial dynamics protein markers were significantly higher in skeletal muscle of endurance-trained runners compared with sedentary controls in the fasted state, although unaffected by the HFM. Skeletal muscle metabolic flexibility was similar between groups when fasted (p > 0.05), but increased in response to the HFM in endurance-trained athletes only (p < 0.005). Key mitophagy markers, phospho-Pink1 and phospho-Parkin (r = 0.64, p < 0.005), and phospo-Parkin and phospho-Drp1 (r = 0.70, p < 0.05) were correlated only within the endurance-trained group. Autophagy and mitophagy markers were not correlated with metabolic flexibility. In summary, mitophagy may be enhanced in endurance-trained runners based on elevated markers of mitophagy and mitochondrial dynamics. The HFM did not alter autophagy or mitophagy in either group. The absence of a relationship between mitophagy markers and metabolic flexibility suggests that mitophagy is not a key determinant of metabolic flexibility in a healthy population, but further investigation is warranted.