Alteration of Deformability of the Erythrocyte Membrane in Stored Blood

The deformability of stored erythrocytes decreases progressively with duration of storage. This change can be measured in terms of mean pressure required to deform the cells sufficiently to cause them to enter and traverse a micropipette analogue of the microcirculation. The disc shape, with relatively higher surface area to volume ratio, is more deformable than the spherical form; and mean deformability at specific time intervals correlates with reported posttransfusion survival values. Only 76 per cent of red blood cells stored for three weeks were able to pass through a pipette with a minimal dimension of 2.85 μ, a dimension through which all fresh cells pass. This dimension is of magnitude similar to that previously reported for the microcirculation of the spleen. Regeneration of cellular ATP by incubation in adenosine is associated with restoration of mean deformability toward the normal range; and the majority of cells, having regained the biconcave disc shape, has values for individual cell deformability similar to fresh cells. The remaining spherical cells retain their relatively decreased deformability.