Continuous-flow NMR culture system for mammalian cells.

A continuous-flow NMR culture system for mammalian cells has been developed on which 31P-NMR experiments under complete and strictly physiologic conditions have been performed. Observations on the response of the cellular metabolism to stresses such as starvation, low temperature and changes in environmental pH monitored by 31P-NMR are reported. The response of the intracellular pH relative to the external pH of the growth medium is studied. We find that under the experimental conditions used there exists a delta pH varying between less than 0.2 and more than 0.6 pH units. These results are compatible with those obtained using other techniques.