EFFECTS OF HEMOGLOBIN CONCENTRATION ON DEFORMABILITY OF INDIVIDUAL SICKLE CELLS AFTER DEOXYGENATION

To assess the role of intracellular hemoglobin concentration in the de formability of sickle (HbSS) cells after deoxygenation, theologic coef ficients (static rigidity E and dynamic rigidity eta) of density-fract ionated individual sickle erythrocytes (SS cells) were determined as a function of oxygen tension (pO(2)) using the micropipette technique i n a newly developed experimental chamber, With stepwise deoxygenation, E and eta values showed no significant increase before morphologic si ckling but rose sharply after sickling, In denser cells, continued deo xygenation led to steep rises of E and eta toward infinity, as the cel l behaved as a solid, The pO(2) levels at which theologic and morpholo gic changes occurred for individual SS cells during deoxygenation vari ed directly with the cell density, The extent of recovery in E and eta during reoxygenation varied inversely with the cell density, These re sults provide direct evidence that the intracellular sickle hemoglobin (HbS) concentration of SS cells plays an important role in their theo logic heterogeneity in deoxygenation and reoxygenation. The elevations of eta during pO(2) alteration were greater than those of E, especial ly for the denser cells, suggesting the importance of the elevated dyn amic rigidity in initiating microcirculatory disturbances in sickle ce ll disease. (C) 1995 by The American Society of Hematology.