Osmometric Behavior of Normal Human Erythrocytes.

It is generally accepted that when erythrocytes are suspenided in hypotonic solutions thev first take up water and swell, and theni at some critical tonicity burst and allow hemoglobin to escape. While there are many indications that the permeability of these cells to both salts and water may vary considerably in different conditions (1, 2, 3), quantitative data on the osmometric behavior of either normal or abnormal erytlhrocytes are scarce. Methods used in clinical studies of the osmotic fragility of erythrocytes are mostly limited to qualitative observations of hemolysis as anl inidication of the rupture of the cells. Quantitative methods for estimating the amounts of hemoglobin liberated from erythrocvtes in salt solutions of different tonicities were devised in 1903 by Arrhenius and Madsen (4) and in 1921 by Hastings (5), each making use of visual colorimetry; and recently Waugh and Asherman (6) and Hunter (7) used photoelectric colorimetry for the same purpose. Such methods permit the estimationi of the number of cells ruptured at each step of a hemolytic series but tell nothing of the osmotic behavior of the cells during stages of their swelling up to the point of rupture. In 1939 we developed a method (8) for measurement of changes in volume of erythrocytes in hypotonic salt solutions, but this method did not account for the swelling of cells remaining intact after hemolysis of part of the cells at critical tonicities. That method has since been elaborated, as here described, to include quanititative mieasurements of hemolysis as well as the volume of the red cells at each tonicity in a series. These parallel determinationis permit the calculationi of the swelling of intact cells both before hemolysis begins and in solutions where partial hemolysis has occurred. Data obtained by this method in studies of normal human erythrocytes are reported here. Data on abnormal types of human erythrocytes and erythrocytes of a number of other species will be reported later. METHOD