Figure 7. Well-oxygenated cells release pyruvate and hypoxic cells consume pyruvate in the media.

(A) 143B, (B) Hep3B, and (C) H9c2 cells were seeded in pyruvate-free DMEM supplemented with 10% dialyzed FBS and 50 μM pyruvate and cultured in 21% or 2% oxygen. After 24 h, pyruvate concentrations in culture media were determined. Control groups represented the initial concentration of pyruvate. Error bars indicate SD of triplicates. (D and E) 143B and HeLa cells were cultured under 2% O₂ with addition of 0, 0.05, 0.2 or 1 mM pyruvate for 3 days. Cell proliferation rate was measured. (F) 143B cells were cultured in pyruvate-free medium under 21% O₂ for 48 h. The conditioned medium was then collected, supplemented with uridine, and used to culture 143B206 cells. The proliferation rate of 143B206 cells in the conditioned media was measured. Error bars indicate SD of ≥ 5 replicates. *p < 0.05. **p < 0.01.