Figure 2.

Delayed response of myogenic or atrophic factors to LA overload. The levels of AMPK-mediated inhibition of mTOR (decreased p-raptor and p-P70-S6K) and of Sirt1 and PGC-1α in myotubes treated with lactate (LA, 8 mM) for 24 h were significantly different when compared to control myotubes (A, B). Myogenic factors (myogenin, MyoD and MHC) in LA-treated myotubes were significantly lower, while atrophic factor (MAFbx) was significantly higher than control myotubes (C, D). Akt-mediated inhibition (phosphorylation) of FOXO3a was significantly blocked by LA treatment for 24 h (E, F). The mean band intensities quantified from two independent experiments (n=3) were compared, and representative bands were presented. *p<0.05, **p<0.01 by unpaired t-test.