Abstract
Summary
An instrument to determine the oxygen association-dissociation equilibrium of whole blood has been developed. Only one drop of blood sample is required to trace automatically the oxygen-red blood cell equilibrium curve in the direction of deoxygenation and reoxygenation within a total of less than 10 min. The whole blood is suspended in the form of a thin liquid film reenforced by a micromesh. The partial pressure of oxygen is changed continuously with a gas-mixing pump while simultaneously being recorded by polarographic oxygen electrodes. The spectral change of red blood cells is recorded by a dual-beam spec-trophotometer.
Using this instrument it is shown that the oxygen equilibrium curve of sickle cells obtained during deoxygenation is shifted to a higher oxygen affinity as compared to those obtained during reoxygenation. This hysteresis-like behavior of equilibrium curves is also reflected in the Hill constant, n, which is greater for deoxygenation than for reoxygenation. On the other hand, if deoxygenation is completed rapidly, the sigmoidness of the reoxygenation equilibrium curve and its oxygen affinity are greater than that obtained after slow deoxygenation. Hysteresis-like behavior is the postulated consequence of intracellular polymerization of sickle hemoglobin.
The authors wish to thank Dr. George Brewer from the University of Michigan for helpful comments, and to acknowledge the cooperation kindly extended to them by the Comprehensive Sickle Center of Wayne State University in supplying blood samples and the support of a WSU Faculty Research Award, and a grant from NHLI.
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