FACTORS GOVERNING OXYGEN AFFINITY OF HUMAN ADULT AND FOETAL BLOOD

In newborns and pregnant and nonpregnant adults, oxygen half saturation pressure (P50) of blood and of dialysed haemoglobin solutions with and without added 2,3 diphosphoglycerate (2,3 DPG) or adenosine triphosphate (ATP) has been examined. Maternal blood has been found to have a higher P50 (30.5 mm Hg) than the blood of the control subjects (26.1 mm Hg) and of the newborns (22.9 mm Hg). In the dialysed haemoglobin solutions of maternal and foetal blood. P50 fell to 19.7 mm Hg and rose after addition of 2,3 DPG by 9.7 mm Hg in the maternal dialysate and by 2.7 mm Hg in the foetal dialysate. The effect of ATP on P50 was less pronounced. 2,3 DPG, ATP, carbonic anhydrase activity and red cell potassium and sodium concentrations have been examined in the blood of the three groups. In maternal blood these substances were slightly but insignificantly elevated compared to the blood of the controls. The results are discussed in respect of the different oxygen affinities of the three kinds of blood. © 1969.