Buoyant density of EMT6 fibrosarcoma cells: I. effect of hypoxic growth conditions in vitro

Abstract

The effect of hypoxic culture conditions in vitro on the growth, survival and buoyant density of cancer cells was examined. EMT6 fibrosarcoma cells in the exponential-phase of growth were incubated at 37°C for different times; they were placed in sealed vacuum chambers that contained oxygen ranging in concentration from < 10 ppm (anoxic) to 2.1 x 10 5 ppm (aerobic). After incubation, the cells were centrifuged under isopyknic conditions in linear gradients of Ficoll to determine their buoyant density. Cells that were grown under hypoxic conditions in vitro became less dense than control cultures that were incubated in air. The actual density differences depended on the time of growth and the level of hypoxia. However, these density changes were reversible if the cells were transferred from hypoxic to aerobic conditions before density analysis.