Using the SensorDish Reader, we monitored pericellular pO2 levels in mammalian cell cultures and showed cell density dependent oxygen consumption and variation in cellular oxygen demand in response to toxic compounds. The density dependent differences observed at 19% pO2 were also observed at 7% pO2, a more physiologically relevant oxygen level. At higher cell densities, in both pO2 levels, diffusion of O2 from the atmosphere into the media was insufficient to compensate for O2 utilization by the cells. This is important for cellular studies as numerous examples show cellular response varies with localized O2 levels.
In addition, cell culture media without any cells took at least seven hours to reach equilibrium when exposed to a 7% pO2 atmosphere. Therefore, pre-incubation of the media at the desired oxygen level is recommended and utilization of the Coy O2 Control Glove Box enables control and maintenance of the desired oxygen level during pre-incubation, set-up, incubation, and treatment.
Also, gaseous pO2 during incubation is a poor measure of the pericellular pO2 to which the cells are actually exposed. The SDR allows for constant and rapid quantification of pericellular pO2 levels that are a more realistic measure of the oxygen concentration that cells are actually experiencing. This, in turn, can be used as a measure of cellular oxygen demand and metabolic function.