Figure 7.

The levels of gluconeogenic amino acids are significantly upregulated by hypoxia and iron deficiency but not because of increased synthesis. A: Relative mRNA abundances of serine dehydratase, normalized to levels of RPL13a, were determined by quantitative RT-PCR B: Levels of gluconeogenic amino acids were analyzed by GC-MS with freeze-clamped liver tissues. C: HepG2 cells were supplemented with fresh 25 mmol/L [U-¹³C₆]glucose. After labeling for 24 h, metabolites were extracted and analyzed by GC-MS. Bars represent the mean ± SE of three independent experiments performed in triplicate. A.U., arbitrary units; H, hypoxia (1% O₂). *P < 0.05 and **P < 0.01 indicate the difference among the groups.