NAC treatments significantly alleviated the reduction in the diameter of C2C12 myotubes induced by TNF-α through inhibiting ROS. (A) TNF-α induces increased ROS levels in C2C12 myotubes; (B-E) NAC treatments significantly alleviated the reduction in the diameter of C2C12 myotubes. C2C12 myotubes were incubated with TNF-α in the presence or absence of NAC (5 mM) for 24 h. Then, immunodetection was performed to determine the presence of MHC in C2C12 myotubes, and the value of diameter of C2C12 myotubes was expressed as the mean ± SEM from three independent experiments; (F) NAC could inhibit ROS caused by TNF-α treatment. DCF fluorescence intensities in C2C12 myotubes suffered from TNF-α treatment. NC: C2C12 myotubes without any treatment; TNF-α: C2C12 myotubes treated with TNF-α only; TNF-α + NAC: C2C12 myotubes treated with TNF-α and NAC simultaneously. *, P<0.05 versus NC; #, P<0.05 versus TNF-α. ROS, reactive oxygen species; NAC, N-acetyl-L-cysteine; MHC, myosin heavy chain; DCF, dichlorofluorescein.