Figure 3.

Mildly hypoxic conditions fail to increase extracellular concentration of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adeosine monophosphate (AMP), and adenosine. (A) Schematic of experimental procedure. Cells were incubated in normoxic (95% air, 5% CO₂) or hypoxic (95% N₂, 5% CO₂) chamber for 20 or 120 minutes. Samples were measured by high-performance liquid chromatography (HPLC). (B) Representative HPLC chromatograms of normoxia and hypoxia samples. Standards of adenosine, AMP, ADP and ATP (0.1 and 0.3 μmol/L each) are shown on top. (C, D) Histogram summarizing the mean concentrations of adenosine, AMP, ADP and ATP after 20 minutes (C) or 120 minutes (D) normoxia (n=4) and hypoxia (n=4). Concentrations of ADP were below detection level in all experimental condition.