Trapping radioactive carbon dioxide during cellular metabolic assays under standard culture conditions: Description of a unique gas-capturing device

Measurement of carbon dioxide levels has been employed to follow cellular metabolic reactions for quite some time. By radio-labeling substrate molecules and evaluating the radioactivity levels of the carbon dioxide released, insight into metabolic pathways can be gleaned. Currently, no carbon dioxide capturing device is available that can be used with large volume cell monolayers growing under standard conditions within a regular commercially available culture flask. In this note we describe a simple device for collecting radio-labeled carbon dioxide from a standard culture flask. The device is independent of the culture flask, but can be attached for metabolic measurements allowing cells to be grown under standard conditions prior to study. The presented design permits convenient transfer of the device between flasks without contaminating or disturbing cells growing within the flasks. Data are presented demonstrating the reproducibility of measurements made with multiple devices with different substrate concentrations and varying periods of time, ranging up to 3 h.