Figure 4.

The time‐course effect of preincubation at high glucose concentration on AMPK phosphorylation in vitro. After preincubation with 30 mM glucose for 4, 12, or 24 hours, the HepG2 hepatocytes and C2C12 myotubes were treated with berberine or metformin at 15 mM glucose for 4 hours. Then, the cells were collected for Western blot analysis. Data are expressed as mean ± SEM; **P < 0.01 and ***P < 0.001 versus corresponding control (without metformin or berberine treatment). ^## P < 0.01 versus control of 4 hours. AMPK, adenosine monophosphate–activated protein kinase; SEM, standard error of mean