Fig. 1

L-carnitine blocks TNF-α-induced myotube atrophy in C2C12 cells. A C2C12 cells were grown in DMEM (growth medium, GM) for 24 h and then changed to differentiation medium (DM) for 3 days. After that, differentiated C2C12 cells were treated for 2 h with 100 ng/ml TNF-α, and then were simultaneously treated with L-carnitine and TNF-α for an additional 24 or 48 h. B Photomicrographs of cultured myotubes after treatment with water (as vehicle), 100 ng/ml TNF-α, a combination of TNF-α (100 ng/ml) with 100 μg/ml or TNF-α (100 ng/ml) with 1000 μg/ml of L-carnitine. C Quantification of the average myotube diameter after 24 h of treatment with water, TNF-α, or TNF-α in combination with the two different concentrations of L-carnitine. Data were plotted as the means (n ≥ 90 myotubes per condition) ± SEM. D A representative Western blot of MuRF1, MAFbx and GADPH following treatment with the combination of 100 ng/ml TNF-α and 1000 μg/ml of L-carnitine after different time points. A representative Western blot of MuRF1, MAFbx and GADPH protein expression. E A representative Western blot of MuRF1, MAFbx and GADPH protein expression. The data shown represent the means ± SEM of three independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001