Role of orthophosphate concentration in the regulation of ribose phosphate synthesis and purine metabolism in Ehrlich ascites tumor cells.

Concentrations of intracellular orthophosphate were determined in Ehrlich ascites tumor cells incubated with glucose, inosine, or uridine in media of different orthophosphate concentration. The effects of orthophosphate concentration on the accumulation of lactate and of phosphoribosyl pyrophosphate and on concentrations of ribose 1-phosphate and ribose 5-phosphate in tumor cells incubated with glucose were also determined. Both the phosphorolysis of inosine and the rate of catabolism of ATP in cells incubated with 2-deoxyglucose were also influenced by the orthophosphate concentration of the medium.