Abstract
EMT6 fibrosarcoma cells were grown to the exponential phase in tissue culture and incubated at 37°C under hypoxic conditions. Buoyant density was determined as a function of the time in hypoxia. Hypoxia was produced in two ways. The first involved incubation of the cells in sealed aluminum chambers containing 95% N2, 5% CO2 gas, and <10 ppm oxygen, resulting in the cells rapidly becoming exposed to the hypoxic environment. After incubation at 37°C, they were centrifuged in linear Ficoll gradients to their isopycnic density. A significant decrease in density was found after 4 h, and prolonged incubation up to 24 h did not result in further change. This density change was reversible on transfer back to aerobic conditions, with the hypoxic cells reverting to their aerobic density after about 10 h reincubation in air. The second method of producing hypoxia involved growing about 8×106 cells in a medium-filled air-tight container. Hypoxia was produced gradually as the oxygen in the medium was consumed by cellular respiration. Similar results were obtained; that is, hypoxic cells became significnatly less dense. However, when the level of hypoxia was varied between 4000 and <10 ppm at 2-h intervals after the cells had depleted all of the original oxygen, no significant difference in density was found between hypoxic and aerobic cells.
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Ng, C.E., Koch, C.J. & Inch, W.R. Buoyant density of EMT6 fibrosarcoma cells. Cell Biophysics 2, 153–163 (1980). https://doi.org/10.1007/BF02795841
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DOI: https://doi.org/10.1007/BF02795841