The chemical decomposition of glutamine to ammonia and pyrrolidonecarboxylic acid
was studied at 37 "C in a pH range of 6.8-7.8 in different media preparations containing
various amounts of fetal bovine serum. The media type influenced the decomposition
rate, and the first-order rate constants increased with increasing pH values.
The serum concentration had little or no effect on the decomposition rate. The importance
of chemical decomposition of glutamine on the analysis of glutamine and ammonia
metabolism was illustrated by an example of batch cultivation of a hybridoma cell
line. The difference between the apparent uptake rate of glutamine and the actual
uptake rate (which is corrected for the chemical decomposition) is shown to be as high
as 200%. Similar discrepancy between the apparent and actual ammonia production
rate is observed. Mathematical analysis was carried out to develop the relationship
between the apparent and actual glutamine uptake and ammonia production rates.
The analysis reveals that there are three important dimensionless parameter ratios
that govern the difference between the apparent and actual glutamine uptake and
ammonia production rates.