Correlation between growth rate, cell density, and intracellular concentrations of cyclic nucleotides in chemostat cultures of mouse L1210 cells.

Constant intracellular concentrations of both adenosine 3',5' cyclic monophosphate (cyclic AMP) and guanosine 3',5' cyclic monophosphate (cyclic GMP) were obtained when mouse leukemia L1210 cells were cultivated under steady-state conditions in the chemostat. When L1210 cells were maintained at a constant growth rate in the chemostat, the mean steady-state intracellular concentration of cyclic AMP decreased with increasing cell density, while the concentration of cyclic GMP remained unchanged. When cell growth rate was increased by three-fold, independently of cell density, in the chemostat, then the mean steady-state intracellular concentration of cyclic GMP increased by 3.6-fold, whereas that of cyclic AMP increased by only 22%. The ratio of cyclic AMP to cyclic GMP was found to decrease with increasing cell growth rate in the chemostat. Our results show that a close correlation exists between the steady-state intracellular concentrations of cyclic nucleotides and changes in both cell growth rate and cell density in chemostat cultures of L1210 tumour cells.