Effect of Osmotic Shrinking and Swelling of Red Cells on Whole Blood Oxygen Affinity

Abstract

The effect of osmotically induced alterations in mean corpuscular hemoglobin concentration (MCHC) on oxygen affinity of hemoglobin was studied in blood cells containing various concentrations of 2,3-diphosphoglycerate (DPG). At normal DPG concentration (0.88 mol/mol Hb) there was a positive correlation between MCHC and whole blood oxygen affinity (P₅₀); the magnitude of the effect, expressed as δP₅₀/δMCHC, was 0.17, a value considerably smaller than that reported by previous investigators. At low DPG concentration (< 0.2 mol/mol Hb) the value of δP₅₀/δAMCHC was 0.40; at DPG levels above normal (> 1.3 mol/mol Hb) no relationship between MCHC and P₅₀ was found. The results are discussed in relation to the various changes in the intracellular milieu on osmotic manipulation, and it is concluded that the alterations of P₅₀ are due mainly to changes in intracellular ionic strength.

Key Words:

• DPG
• MCHC
• osmotic effects
• P₅₀