Pro co2 carbon dioxide controller

For the different experimental conditions, initial solutions were prepared with DMEM/Ham’s F-12 medium/tris base/Mops base (3:1:0.25:0.25) containing 10% FBS, penicillin (100 U/ml), and streptomycin (100 μg/ml), as described elsewhere (6 (link)). The buffering capacity of the medium was modified by changing its initial pH with tris and Mops base to obtain a pH of 7.4 at the various CO₂ concentrations (pCO₂ of 5, 7.5, 10, and 20% for 30 to 40, 50 to 55, 60 to 80, and ~120 mmHg, respectively). In some experiments modeling extracellular acidosis, an initial pH of 6.8 was used, resulting in a final pH of 7.2 and a pCO₂ of 40 mmHg. The desired CO₂ and pH values were achieved by equilibrating the medium overnight in a humidified chamber (C-Chamber, BioSpherix). The atmosphere of the C-Chamber was controlled with a PRO CO₂ carbon dioxide controller (BioSpherix). In this chamber, cells were exposed to the desired pCO₂ while maintaining 21% O₂ balanced with N₂. Before and after CO₂ exposure, pH, pCO₂, and pO₂ values in the medium were measured using a Stat Profile pHOx blood gas analyzer (Nova Biomedical). Experiments were started by replacing the culture medium with the CO₂-equilibrated medium and incubating in the C-Chamber for the desired time.