Changes in the Stability and Potential of Cell Suspensions

1. Human and sheep erythrocytes, when placed in 0.01 N buffer solutions at reactions more acid than pH 5.2, undergo a progressive change in potential, becoming less electronegative or more electropositive. This change usually occurs within 2 hours at ordinary room temperatures. It did not occur when rabbit erythrocytes were used. 2. This change is due primarily to the liberation of hemoglobin from some of the cells. 3. Hemoglobin, even in very low concentrations, markedly alters the potential of erythrocytes in the more acid reactions. This is due to a combination between the electropositive hemoglobin and the erythrocytes. The effect of the hemoglobin is most marked in the more acid solutions; it occurs only on the acid side of the isoelectric point of the hemoglobin. 4. The isoelectric point of erythrocytes in the absence of salt, or in the presence of salts having both ions monovalent, occurs at pH 4.7. This confirms the observations of Coulter (1920-21). Divalent anions shift the isoelectric point to the acid side. 5. The effect of salts on the potential of erythrocytes is due to the ions of the salts, and is analogous in every way to the effect of salts on albumin-coated collodion particles, as discussed by Loeb (1922-23).