Normal human erythrocytes were separated according to in vivo age by ultracentrifugation. The “young” and “old” erythrocytes had mean cell ages of approximately 40 and 79 days, respectively. “Young” erythrocytes had a lower oxygen affinity and a higher heme-heme interaction than did “old” erythrocytes. This indicates an impairment of the oxygen-carrying function of erythrocyte hemoglobin with age.
