Simulation of continuous blood O2 equilibrium curve over the physiologic pH, DPG and pCO2 range

We analyzed 56 O 2 equilibrium curves of fresh human blood, each from 0 to 150 Torr PO 2. The data were collected over ranges of values for the 2,3-diphosphoglyceric acid-to-hemoglobin concentrations ratio [DPG]/[Hb] of 0.2-2.7, for pH of 7.0-7.8, and for PCO 2 of 7-70 Torr. Each curve was characterized according to the Adair scheme for the stepwise oxygenation of Hb, and the resulting constants (\u3b1 1, \u3b1 2, \u3b1 3, \u3b1 4) were analyzed to allow the simulation of the entire O 2 equilibrium curve under any conditions of [DPG]/[Hb], pH, and PCO 2 in the specific range. This analysis provides a powerful tool to study the affinity of Hb for O 2 within the red blood cell and to predict the shape of the O 2 equilibrium curve in various physiological and pathological states. Other attempts to predict blood O 2 affinity have considered only P 50 (the PO 2 at one-half saturation with O 2) or have provided too little data for continuous simulations