EFFECT OF BLOOD-STORAGE ON ERYTHROCYTE WALL INTERACTIONS - IMPLICATIONS FOR SURFACE-CHARGE AND RIGIDITY/

In this report, we study, under flow conditions, the interactions of s tored erythrocytes with an artificial surface: a microelectrode whose charge density ranges from -15 to +27 mu C/cm(2). Interactions consist of red cells slowly circulating on the microelectrode and exerting a real contact with the electrode. Interaction is detected and measured by transient fluctuations of the electrolyte resistance obtained by im pedance measurement of the microelectrode. Effects of aging induced by storage of whole blood at 4 degrees C show that the surface charge of erythrocytes rapidly decreases when blood is stored for more than 6 d ays under our experimental conditions. In comparison with trypsin-trea ted erythrocytes, an eight day storage induces a 60% decrease in the s urface charge of red cells. After two weeks of storage, red cells are no longer negatively charged, presumably be cause of removal of sialic acid. Cells rigidity is significant after 6 days of storage and influ ences the electrical contact. Membrane rigidity increase could arise f rom the surface charge decrease. Finally, the surface charge decrease could be of importance in the use of stored blood.