31P NMR studies on recovery from hypoxia of human tumor cells

We describe the use of 31P NMR spectroscopy in the study of metabolic changes related to hypoxia in cultured human tumor cells in vitro. The 31P NMR spectrum can easily distinguish between metabolically active cells, metabolically inactive "dormant" cells, and necrotic cells. A crucial observation was that of the ability of the "dormant" cells to resume active metabolism on incubation with oxygen after long periods of hypoxia.