CHANGE IN THE ENERGY-METABOLISM OF ASCITES TUMOR-CELLS WHEN THE PH DECREASES

Ascites tumor cells of thymoma EL-4 in Hanks' salt solution exhibited endogenous respiration sufficient to maintain the A TP level in the cells; a decrease in the pH to 6.0 did not cause any change in the endogenous respiration and ATP level. Glycolysis did not affect the respiration of EL-4 cells but suppressed the respiration of Ehrlich ascites carcinoma (EAC)* cells by 40% (the Crabtree effect); respiration of cells of both lines was significantly inhibited (by a factor of four) in the presence of simultaneous addition of glucose and lactate and a decrease in pH. Endogenous glycolysis was absent in EL-4 cells, and in EAC cells a low level of it was observed only when the pH decreased. Addition of glucose activated glycolysis (both anaerobic and aerobic) in both cell lines; this exogenous glycolysis was inhibited by 50% when the pH decreased to 6.0. Inhibition of respiration in EL-4 cells at pH 7.3 and 6.0 did not cause any decrease in their A TP content if glucose was present in the medium, probably on account of a suppression of ATP consumption. Incubation of these cells in the absence of respiration and glycolysis led to a sharp drop in their ATP level, whereas a decrease in pH slowed down this depletion.