Summary

Abstract

It is clear from these studies that the methods used for sample preparation prior to the measurement of erythrocyte deformability are of crucial importance. Since bulk erythrocyte filtration methods are sensitive to the effects of contaminating platelets, leucocytes and plasma proteins, it is essential to remove these extrinsic factors so that a pure erythrocyte suspension can be tested. This can be achieved either by passage of whole blood through cotton wool or by centrifugation at 600 g and aspiration of the middle of the packed erythrocyte layer. Provided one or other of these procedures is used, and the resulting cell suspension is checked visually in a counting chamber, whole blood can be stored for several hours in heparin or K₂EDTA at room temperature prior to testing. Storage for 24 hours or more in citrate-phosphate-dextrose-adenine (blood bank anticoagulant preservative solution) was suggested by Holger Schmid-Schöbein, in discussion, as a possibility for the future. Once resuspended in buffer, the test erythrocytes should be filtered immediately or, if there is any delay, they should not be suspended in Tris buffer since cell swelling will occur. HEPES and phosphate buffers are preferable. An alternative is to resuspend the erythrocytes in standardised donor plasma.