Osmotic swelling and hole formation in membranes of thalassemic and spherocytic erythrocytes

Osmotic swelling and kinetics of the pore formation in the membranes of spherocytic, thalassemic, and normal erythrocytes were studied by measuring the time-dependent capacitance and conductance at a frequency of 0.2 MHz. No significant difference between the swelling rate of control and spherocytic cells was observed, whereas slower kinetics of swelling were found for thalassemic cells. Time records of the conductance indicate that the probability of the pore formation in the stretched membrances varies in the following order: thalassemia < control < spherocytosis. Based on these findings it was concluded that the erythrocyte swelling is controlled by the initial cell shape, volume, intracellular hemoglobin concentration, and elastic membrane properties, whereas the kinetics of the pore formation depend solely on the resistivity of the stretched membrane of the swollen RBC to the osmotic shock. Therefore, it was assumed that investigations of the pore formation may be used not only for examinations of spherocytic and thalassemic cells, but also for normocytic, normochromic, biconcave-shaped RBCs with altered membrane elasticity.