RHEOLOGICAL STUDIES OF HB SS BLOOD - INFLUENCE OF HEMATOCRIT, HYPERTONICITY, SEPARATION OF CELLS, DEOXYGENATION, AND MIXTURE WITH NORMAL CELLS

Abstract

Studies of the rheological properties of Hb SS (sickle cell anemia) blood indicate that the marked increase in viscosity with deoxygenation is primarily due to cell-cell interaction of cells which were not permanently deformed. The permanently deformed cells, the bottom fraction of cells separated by centrifugation, show only a fraction of the increase in viscosity compared to top cells, when each was deoxygenated. Top cells showed a greater degree of morphologic change with deoxygenation compared to bottom cells. The viscosity of deoxygenated Hb SS blood was disproportionately reduced by the addition of compatible deoxygenated Hb AA cells. A mixture of 1/4 Hb AA cells and 3/4 Hb SS cells reduced the viscosity of deoxygenated Hb SS blood 50%. Studies of Hb SS cells in hypertonic media indicate that hypertonicity per se does not cause sickling. Normal and Hb SS erythrocytes both showed identical changes in rheological properties when suspended in hypertonic serum. Changes in O2 saturation due to a decrease in intracellular pH with certain hypertonic media may lead to sickling when Hb SS blood is at intermediate 02 tension levels. The addition of x-ray contrast material to blood resulted in the changes due to hypertonicity but did not cause sickling of Hb SS cells. The contrast material lowered the pH of the media and raised intracellular pH.