Abstract
Oxygen (O2) is an essential element for aerobic respiration. Atmospheric concentration of O2 is approximately 21%. Mammalian cells, however, are generally adapted to O2 levels much lower than atmospheric conditions. The pericellular levels of O2 must also be maintained within a fairly narrow range to meet the demands of cells. This applies equally to cells in vivo and cells in primary cultures. There has been growing interest in the performance of cell culture experiments under various O2 levels to study molecular and cellular responses. To this end, a range of technologies (e.g. gas-permeable technology) and instruments (e.g. gas-tight boxes and gas-controlled incubators) have been developed. It should be noted, however, that some of these have limitations and they are still undergoing refinement. Nevertheless, better results should be possible when technical concerns are taken into account. This paper aims to review various aspects of O2 level adjustment in primary cell cultures, regulation of pericellular O2 gradients and possible effects of the cell culture medium.