2,3-Diphosphoglycerate Content of Human Arterial and Venous Blood

THE glycolytic intermediate, 2,3-diphosphoglycerate, is an intracellular regulator of the oxygen affinity of haemoglobin1,2. At high altitudes there is a direct relationship between the decreased oxygen affinity of haemoglobin and the increased concentration of diphosphoglycerate in the blood3. This was explained by Benesch et al.4 and Chanutin et al.5, who found that the binding of diphosphoglycerate to haemoglobin reduces the oxygen affinity, and by our finding that the concentration of diphosphoglycerate increases when the red cells are incubated under low oxygen tension6,7, thereby releasing oxygen from haemoglobin. For the same reason, the oxygen tension is reduced during the circulation of blood from the pulmonary alveoli to the tissues; the decreased level of the diphosphoglycerate facilitates the binding of oxygen to haemoglobin in the pulmonary alveoli and the increased level of the diphosphoglycerate in the blood of the capillaries decreases the affinity of haemoglobin for oxygen. We have measured the amount of 2,3-diphosphoglycerate and other glycolytic intermediates in arterial and venous blood to test this supposition.