[Importance of pH- and osmolarity-dependent changes in deformability- determining factors on the filterability of human erythrocytes].

The deformability of erythrocytes was characterized by measuring their filterability through cellulose filters under low pressure, their cellular geometry and elastic membrane properties. A decreased filterability of suspensions of washed erythrocytes with increasing pH (5.5-7.9) and osmolarity (220-510) was found. The influence of RBC-deformability determining factors on the measured quantity (relative time of filtration) was determined. It is concluded that the viscosity of the cell interior has a predominating influence on the filterability through cellulose filters among all experimentally changed factors determining the deformability. The influence of the cell volume on the filterability is small compared with that of secondary effects of volume changes (dilution or concentration of hemoglobin, changes of cell volume concentration at constant hematocrit). The influence on the erythrocyte volume increases with decreasing pore size.