Potassium transport and control of glycolysis in human erythrocytes

Abstract

Defibrinated blood, stored for 3 days at 5 C, was found to accumulate fructose diphosphate and dihydroxyacetone phosphate. After these cells were washed free of extracellular substrate, the conversion of these sugar phosphates to lactate and inorganic phosphate was found to be inhibited by the absence of K in the medium or by the presence of ouabain. No intermediate compounds accumulated. Attempts were made to duplicate the metabolic effects of extracellular K by adding compounds designed to increase the reactants of the oxidative phosphorylation reaction of glycolysis. Inorganic phosphate was almost without effect; pyruvate increased both the oxidative and reductive reactions but not the net conversion of sugar phosphate to lactate. Only glucose accelerated net conversion of sugar phosphate to lactate and inorganic phosphate. The data are best explained by the idea that the glycolysis of sugar phosphate is limited by the amount of adenosine diphosphate (ADP) available and that the effect of external K is to supply this ADP by its stimulating effect on the membrane-bound adenosine triphosphatase (ATPase).