The effect of magnesium on glycolysis of permeabilized Ehrlich Ascites tumor cells

We have previously observed that extracellular Mg 2+ influences the phosphofructokinase (PFK) activity of intact Ehrlich Ascites tumour cells (EATC). In this study we have investigated the mechanism by which Mg 2+ modulates this key glycolytic enzyme in EATC made permeable to the cation by either digitonin or dextran sulphate. Results showed that when Mg 2+ is freely permeable to the cytosol, the in vivo PFK activity, calculated as FDP G6P ratio, is not increased as it is in intact cells. We also observed that in permeabilized cells Mg 2+ determines the increase of glucose 6 phosphate (G6P), fructose 1,6 bisphosphate (FDP) and lactate production. We hypothesize that extracellular Mg 2+ regulates PFK and glycolysis in these neoplastic cells not by entering the cytosol but by a specific interaction with the plasma membrane.