Oxygen sensing refers to the ability of cells to detect and respond to changes of intracellular oxygen concentrations. Because cells often experience decreased oxygenation under both physiological and pathological conditions, oxygen sensing is also referred to as hypoxia sensing. This entry focuses on the common mechanisms of oxygen sensing in mammalian cells.
Molecular oxygen (dioxygen O2) is a vital element for the majority of life forms on earth. The atmospheric O2concentration is approximately 20.9 % at the sea level. Under physiological conditions, oxygen concentrations are maintained approximately in the range of 2–10 % depending on the tissue types in mammals. However, mammalian cells can be exposed to high levels (up to 20.9 %) of oxygen concentrations due to physical wounding. On the other hand, oxygen concentrations in mammalian cells can decrease to 0–1 % due to certain diseases including ischemia, cardiovascular...