Effect of ammonium ions on the aerobic glycolysis in Ehrlich ascites tumor cells.

The effect of ammonium ions on aerobic glycolysis has been studied in Ehrlich ascites tumor cells. The inhibition of respiration caused by 5-25 mM glucose, fructose or mannose is increased by the presence of 0.5-20 mM NH4+. Under these conditions, more glucose is used and a crossover analysis of intermediate metabolites of glycolysis indicates an increase in the glycolytic flux. In spite of the stimulation of glycolysis, the production of lactate decreases in the presence of ammonium ions, although the concentration of free alanine (glutamate and aspartate) is increased. Ammonium ions enhance the oxidation of cytochromes c and a caused by glucose, and decrease the adenine nucleotide pool and the ATP/ADP ratio. These effects of ammonium ions are observed when glucose is present in the incubation medium, and do not occur when only ammonium salts were supplied to the cells metabolizing endogenous substrates.