Evaluation of the Coordinated Control of Activated Glycolysis and Respiration by Orthophosphate and ADP in Ascites Tumor Cells

Abstract

During the first minute after addition of glucose to respiring ascites tumor cells, there are two internally regulated glycolytic units: hexokinase through phospho-fructokinase; and triose-P dehydrogenase through lactate dehydrogenase. The velocity of the former, V _PFK, and of the latter V _LDH, as well as the velocities of respiration and ATP hydrolysis are linear functions of both ADP and intracellular Pi. Expressions for d/dt(ADP) and d/dt(P_i) are solved for ADP, assuming various combinations of ADP and P_i dependence for the velocities. Comparisons of theoretical and experimental ADP curves indicate that neither ADP nor P_i control both V _PFK and V _LDH, but that P_i probably controls V _PFK while ADP controls V _LDH.