Automated continuous measurement of erythrocyte volume under isotonic conditions

The time course of volume changes of erythrocytes, suspended in isotonic solutions containing permeable substances, was studied using a cell monitoring system which was assembled on the basis of Coulter's principle. For comparison, the hematocrit method was employed. The data obtained demonstrated that urea, glycerol, ethanol, and methanol induced a rapid volume increase, whereas glucose and galactose induced a slow volume increase. These results correspond well to the data obtained by the hematocrit method. The present method, which requires only a minimum volume of blood, showed high accuracy and high reproducibility. Thus, the method was considered applicable to experimental and clinical studies of membrane permeability of erythrocytes.