Effect of coenzyme Q10 on C2C12 muscle myotubes in resting and exercise conditions.

Coenzyme Q10 (CoQ) is a multi-functional, fat-soluble, vitamin-like substance that plays an essential role in mitochondrial function. CoQ also acts as a direct and indirect antioxidant, and has also been reported to modulate gene expression. Research into CoQ as a supplement for general health has increased in recent years, with substantial interest in the potential for CoQ to improve muscle health and function, and delay the onset of age-related decline. The focus of this project is to assess the effect of CoQ supplementation on markers of oxidative stress in skeletal muscle cells under resting and exercise-stressed conditions. Mechanistic investigations using a cell culture model of skeletal myotubes, applying a biochemical exercise mimic treatment will be undertaken.
AIM
To identify the effect of physiological concentrations of CoQ on measures of oxidative stress in non-stressed cells and to measure oxidative stress induced by an exercise mimic treatment in vitro.
METHODS
C2C12 myotube cultures were either treated with a range of physiologically-relevant CoQ concentrations (1-1000 nM) for 24 h or with a range of different exercise mimic treatment protocols which aimed to simulate muscle stress during a range of exercise modalities (3 day x 1 h, intermittent 3 x 1 h, 3 hr continuous, 1 h continuous and intermittent 3 x 5 min). Reactive oxygen species (ROS) production was assessed using the ROS-sensitive dye, DHE, by fluorescence detection.
RESULTS
CoQ treatment reduced ROS production in non-stressed cells at concentrations between 1 nM and 500 nM (16.3% - 24.5% differences in means compared to control). The 24.5% decrease in mean ROS production, induced by 500 nM CoQ was statistically significant (p=0.02, standardised size effect =1.48). Concentrations above 500 nM did not alter ROS production in non-stressed cells.
Biochemical exercise-mimicking increased ROS production compared with control in both the intermittent 3 x 5 min (difference in means of 99% compared to control, standardised size effect = 1.16) and continuous 3 hr (difference in means of 26% compared to control, standardised size effect = 0.66) conditions. There was a decrease in ROS production observed with the 3 day x 1 h treatment (difference in means of 44% compared to control, standardised size effect = 2.51). Only the 3 day x 1 h treatment was statistically significant (p = 0.012).
CONCLUSION
CoQ treatment reduces ROS production at physiologically-relevant concentrations when applied to non-stressed myotubes. Intermittent exercise-mimicking increased cell ROS production, suggesting increased oxidative stress, whereas repeated exercise mimic treatment over 3 days appears to decrease ROS production. Further experiments are needed to confirm these findings.