Influence of temperature 0 oglobin-ligand interaction in vv

ent change in hemoglobin-oxygen affinity was measured as a function of hemoglobin-oxygen saturation. In addition, the CO, Bohr factor and fixed acid Bohr factor were measured as a function of saturation at temperatures of 23, 30, 37, and 44°C. Measurements were made on normal blood and blood with reduced 2,3-diphosphoglycerate (DPG). The influence of tem-perature is greatest at low saturation and is enhanced slightly by DPG depletion. The CO, Bohr factor is increased at high temperatures; this is primarily due to increased carbamino formation with rising temperature, especially at lower oxygen saturation. The effect of DPG on oxygen affinity is reduced at a high temperature and elevated at low temperature. These diverse effects of temperature on hemoglobin-ligand interac-Con require consideration in assessing oxygen delivery when temperature is increased or decreased. hemoglobin-oxygen affinity; oxygen dissociation curve; oxygen saturation; 2,3-diphosphoglycerate; Bohr effect; carbamino; carbon dioxide; P,,, BOHR, HASSELBALCH, AND KRQGH (7) first demonstrated reduced hemoglobin oxygen affinity with increased car-bon dioxide. The classical Bohr effect, was later shown to be due to both the change in pH and the carbamino reaction (16, 18). Within the last ten years, 2,3-diphos-phoglycerate (DPG) has been shown to affect hemoglo-bin-oxygen affinity both by direct bindin by influencing binding of brotons and carbon dioxide t