The oxygen affinity of normal human whole blood measured by double tonometry. II. pH-depending Bohr effect and DPG.

Following another preliminary work on the whole blood oxygen affinity, the Authors have found in this occasion normal values of the pH-depending Bohr effect in healthy subjects of both sexes and different age. Furthermore, the Hb decreasing causes in these cases also a P50 increasing which is mediated by raised DPG levels. However, while in the anemias this effect is constant, many exceptions have been found in physiological conditions. Since these ones have been mainly detected at the maximal DPG levels, the phosphate could modify the affinity not only as allosteric effector, but also by acting on pH and related equilibria as non diffusible free anion. These interferences are difficult to be calculated and often could disturb notably a correct use of the common mathematical model which describes the oxygenation.