This performance allowed for the discovery that the OCR of cells is not constant, rather the OCR naturally adapts to the environmental concentration of oxygen in the culture.

OCR data obtained in cultures grown in flasks or dishes, at 21% oxygen, will be erroneous due to the massively excessive O2 levels, between 2-10 times the values under real oxygen tension occurring in native tissues.

Atmospheric hypoxia between 14% and 6% oxygen show the most stable OCR in the majority of the investigated cell types; within a 40 mmHg and 90 mmHg bracket, which incorporates the most common oxygen tensions in natural tissues.

Specifically, HeLa cells reduce their OCR enormously when DO drops below 30 mmHg (below 4% atmospheric concentration of Oxygen), depicting the progressive switch from OXPHOX to anaerobic glycolysis.

In Petaka G3, that deep hypoxia level is easily achieved when cell growth reaches the final plateau, around 94% confluent. With the Petaka G3 DO-S, researchers can, for the first time ever, conveniently and easily measure physiologically-relevant, real-time oxygen consumption rate for cells in culture, either in the incubator or on the bench for long periods of time and without any special environmental equipment.