Intracellular pH of the Ehrlich Ascites Tumor Cell as It Is Affected by Sugars and Sugar Derivatives

The intracellular pH of the Ehrlich ascites tumor cell has been calculated from the distribution between intracellular and extracellular water of the weak acid, 5,5-dimethyl-2,4-oxazolidinedione-2- 14 C. Extracellular water in the centrifuged cellular layer was measured with inulin labeled with 14 C. The cells were suspended in a Krebs-Ringer-0.025 m bicarbonate buffer or a Krebs-Ringer-0.025 m phosphate buffer. On addition of the fermentable sugars d -glucose, d -fructose, and d -mannose, the fall of pH in the medium corresponded to the lactate concentration. Lactate production was about the same in the two buffers, but the fall of pH was greater in the phosphate buffer because of the greater buffering efficiency of the bicarbonate. In the bicarbonate buffer, intracellular pH fell only slightly until the extracellular pH fell below 6.8. In the phosphate buffer, intracellular pH fell by a considerably greater amount. On addition of nonmetabolized sugars d -galactose, l -arabinose, 3- O -methyl- d -glucose, and methyl-α- d -glucoside, no significant change in either extracellular or intracellular pH was seen. On addition of 2-deoxy- d - arabino -hexose (2-deoxyglucose), there was no significant change in extracellular pH, but intracellular pH fell and remained low. d - arabino -Hexosulose (glucosone) itself caused no significant change in extracellular or intracellular pH. When glucose was added to cells previously incubated with glucosone, lactate production was largely blocked, and the fall in intracellular pH was correspondingly much less than in the absence of glucosone. Prior incubation with glucosone entirely prevented the fall of intracellular pH when 2-deoxyglucose was added.