A STUDY OF THE OSMOTIC BEHAVIOR OF THE HUMAN ERYTHROCYTE*†

Abstract

After hemolysis (by freezing and thawing), the freezing-point depression of whole blood, whole blood-plus-saline (1:1), or whole blood-plus-sucrose solutions was less than before hemolysis; over a range of concentrations from 208 to 747 milliosmoles per kg H2O (mOsm) this difference varied directly with the concentration in highly predictable form. These changes with hemolysis and dilution of the hemoglobin in the extracellular phase are consistent with Adair''s observation that the osmotic coefficient of hemoglobin varies in a curvilinear fashion with its concentration in solution, and thus consistent with osmotic equality between cells and surroundings before hemolysis. Direct measurements on pure hemolyzed red cells and the extracellular phase to which the cells were exposed prior to hemolysis were made by use of a technique for melting-points of microscopic samples. Over a range of concentrations from 210 to 520 mOsm the melting-points of intracellular and extracellular phases were found to be not significantly different. It is concluded that the normal human erythrocyte is in osmotic equilibrium with its surrounding fluid and that this equilibrium is maintained over a wide range of concentrations.