Erythrocytes in sickle cell anemia are heterogeneous in their rheological and hemodynamic characteristics.

Abstract

A B S T R A C T To understand the contribution to the pathophysiology of sickle cell anemia of the different erythrocyte density types present in the blood of these patients, we have studied the viscosimetric and hemodynamic characteristics of four major classes of hemoglobin SS erythrocytes. We have isolated reticulocytes, discocytes, dense discocytes, and irreversibly sickled cells (fractions I-IV) on Percoll-Renografin density gradients. Bulk viscosity was studied in a coneplate viscosimeter and the hemodynamic studies were performed on the isolated, artificially perfused mesoappendix vasculature of the rat (Baez preparation).Bulk viscosity measurements at shear rates of 230 s-' demonstrate that when the cells are oxygenated, fraction I (reticulocyte rich) has a higher viscosity than expected from its low intracellular hemoglobin concentration. The rest of the fractions exhibit moderate increases in bulk viscosity pari-passu with the corresponding increases in density (mean corpuscular hemoglobin concentration). When deoxygenated, all cell fractions nearly doubled their bulk viscosity and the deoxy-oxy differences remained constant. The Baez preparation renders a different picture: oxygenated fractions behave as predicted by the viscosimetric data, but, when deoxygenated, cell fractions exhibit dramatically increased peripheral resistance and the This work was presented, in part, at the 66th Annual

Measurement Techniques for Red Blood Cell Deformability: Recent Advances

“…Sickle RBCs have different morphologies depending on its density (Kaul, Fabry et al,1983;Evans, Mohandas et al,1984). After repeated sicklings, a fraction of RBCs becomes irreversibly sickled cells and they exhibit the most significant loss in deformability.…”

Redox-dependent impairment of vascular function in sickle cell disease

“…Four different fractions of sickle RBCs, reticulocytes, discocytes, dense discocytes, or irreversibly sickled cells (ISCs), have been identified in SCD blood separated on a percoll-renografin density gradient (37). The relative contribution of red cell density to adhesive and obstructive events was investigated in ex vivo mesoceum microvasculature of the rat.…”

Haemorheological changes during human erythrocyte life-span

“…Some rheological properties of red blood cells had been described to undergo age-related changes in human and rabbit samples (6)(7)(8)(9). Present data suggest that the modifications linked to cell-ageing do not involve deformability as tested by filtration technique on Reid and Dormandy apparatus (10).…”

“…Erythrocyte deformability might undergo important changes during its life-span, mainly due to ATP depletion, which could significantly affect the circulatory behaviour of these cells. Significant increase in viscosity has been described during erythrocyte agening (6). Human and rabbit red cells were reported not to alter their membrane rigidity while aging when subjected to micropipette analysis (9).…”