Flow Characteristics of Erythrocytes Subjected to Prolonged Incubation in PBS

Abstract

In some erythrocyte experimental studies, such as the study of protracted or severe hypoxia, it is necessary to incubate erythrocytes for prolonged periods of time. Therefore, it is relevant to determine the effects of incubation on the flow characteristics and the material properties of erythrocytes. It is known (Richterich, et al., 1981) that incubation of RBC beyond several hours in a medium without special additives to preserve the cellular metabolic processes leads to the depletion of glucose and, eventually, of ATP. Without ATP the sodium-potassium pumps no longer function, and an osmotic perturbation takes place producing an alteration of the cell geometry (viz., discocytes into spheroechinocytes) (Schmid-Schoenbein et al., 1983). These changes may be accompanied by a change in the membrane mechanical properties. Both, the sphericity increase and the perturbation of the mechanical properties of the membrane and the cytoplasm, can potentially lead to a change in the cell deformability. The degree to which these two aspects may contribute, if any, to the altered cell deformability is a matter of speculation. Also, it is unclear if rheological indices present a practical means of detecting biochemical damage to these incubated cells. We will address these questions in this paper. While the present experimental conditions are clearly aphysiological, the results of this study will nevertheless be valuable in that they will provide a baseline data on the effect of incubation by itself.