Velocity of O₂ uptake by human red blood cells

Abstract

We have determined the over-all association rate constant, k' c , for the uptake of oxygen by normal human erythrocytes from 0% to 97% initial hemoglobin saturation at pH 7.4 and 37óC. With a modified Hartridge-Roughton rapid-reaction apparatus, we used a small oxygen electrode to follow the oxygen uptake process rather than using the usual photocolorimetric analytical methods. The value of k'c averages 164 mm -1 sec. -1 at 0% initial saturation, rises slowly to over 300 at 50%, and then climbs rapidly to over 1500 at 95%. The theoretical explanation for the increase in k- c with rising initial oxyhemoglobin saturation is based on the increasing prominence of the fourth chemical association rate constant, k- 4 , in the intermediate compound theory of Adair. It is known that k- 4 is several times larger than any of the other three k– s . Submitted on December 19, 1960