THE EFFECT OF IN VIVO AGING OF NORMAL HUMAN ERYTHROCYTES AND ERYTHROCYTE MACROMOLECULES UPON OXYHEMOGLOBIN DISSOCIATION*

Abstract

Comparisons of HbO2 per cent saturation of old and young normal human RBC were made in vitro at a single O2 tension. Ultracentrifugation at 4[degree]C separated heavier oid RBC from lighter young RBC. Ten studies compared old and young intact RBC; 4 studies compared their hemolysates, clarified and dialyzed against deionized water. The samples were separately equilibrated at 37[degree]C in a tonometer system with a gas mixture of PO2=30 mm Hg and PCO2=42 mm Hg. Another equilibration was done at PO2=147 mm Hg and PCO2=42 mm Hg for O2 capacity. Oxygen and CO2 contents were determined by the Van Slyke manometric method. Corrections were made for acids produced by giycolysis. Old RBC had a significantly (p>0.05) greater HbO2 % sat. than young RBC both in intact cells (mean difference=4.35 % sat.) and in clarified dialyzed hemolysates (mean difference=4.71 % sat.). It is concluded that the HbO2 dissociation curve changes with aging of the normal human RBC. The observed alteration of function suggests that the protein, Hb, undergoes a molecular alteration with aging of normal human RBC.