Stimulation by calcium of glucose uptake and lactate production in pigeon erythrocytes.

The rate of glucose conversion into phosphorylated or charged intermediates was determined and related to lactate output and ATP levels. The calcium ionophore A23187 stimulated strongly the production of lactate in pigeon erythrocytes. It required the presence of calcium and simultaneously ATP levels fell down in red cells. The rate of glucose uptake by pigeon erythrocytes was measured as the conversion of [U-14C]glucose into phosphorylated or charged intermediates. A23187 increased the rate of glucose uptake and required the presence of micromolar calcium concentrations. Neither glucose uptake nor lactate production could be related to the decrease of cellular ATP. The results suggest that changes in intracellular calcium alone can stimulate glucose uptake and lactate production.