Atomic force microscopy of the erythrocyte membrane in obstructive jaundice

The erythrocyte intracellular pressure was calculated using a biomechanical model of the erythrocyte and atomic-force-microscopy (AFM) data. The intracellular pressure was characterized as a function of the model erythrocyte morphology. Based on numerical modeling and data of erythrocyte imaging by AFM, a method was developed to estimate the erythrocyte intracellular pressure by comparing experimental data and the results of numerical calculations. Calculations were performed for erythrocytes of dwarf domestic pigs with and without obstructive jaundice that varied in severity. The erythrocyte membrane was affected with increasing disease severity and blood bilirubin concentration, i.e., the erythrocyte volume increased on average, and substantial changes were observed for erythrocyte intracellular pressure relative to its normal value. As an example, an increase in bilirubin concentration from 5 to 96 μmol/L was associated with an increase in intracellular pressure from 0 to 2.2 kPa. An examination of the erythrocyte membrane surface by high-resolution AMF showed that the membrane is disrupted with an increase in bilirubin concentration and displays lesions and an increasing rupture length.