Temperature and oxygenation of human blood at constant total CO2 content.

The influence of temperature on the oxygeneration of normal and 2,3-diphosphoglycerate-depleted human blood suspensions (final hemoglobin concentration: 0.75%) was studied under closed-system conditions (constant total CO2 content) beginning with standard values:pH 7.40, Pco2 40 torr, at 37 degrees C. The present results quantify the temperature-induced changes in Po2 occuring in association with the concomitant acid-base variations prevailing in a closed system. When the temperature was raised from 25 to 42 degrees C, P50 varied from 13.9 +/- 1.1 to 40.7 +/- 1.9 torr in the presence of 2,3-DPG and from 7.6 +/- 0.4 to 24.8 +/- 1.2 torr in the absence of the cofactor. The derived equations correlate Po2 variations with those of temperature (T: 25--42 degrees C) and oxygen saturation (So2:10--90%). The temperature coefficient of oxygenation and the DPG-induced decrease in the heat of hemoglobin oxygenation were shown to be saturation dependent. DPG lowered dlog Po2/dT from 0.0299 to 0.0275 and delta H from --12.9 to --11.8 kcal/mole O2 bound at 50% So2 but had no significant influence on these parameters for So2 less than or equal to 20%. The results suggest that the release of carbamate at the beginning of oxygenation is virtually unaffected by presence of 2,3-DPG in the 25--42 degree C temperature range.