OSMOTIC AND MECHANICAL LYSIS OF HUMAN ERY THROCYTES

The osmotic stability of human erythrocytes upon isotropic membrane st retching in a hypotonical medium depends on the stability of the membr ane lipid bilayer. The osmotic stability increases as the temperature raises, enhancing hydrophobic interactions in the membrane. Thermal de naturation of membranous spectrin does not change the erythrocyte stab ility. The osmotic fragility is also constant at pH 5.5 to 9.0. Free l ong-chain fatty acids interacting with the erythrocyte membrane inhibi t the osmotic lysis of erythrocytes. Membrane modification by glutaric aldehyde (1.0-3.0 mM) significantly increases the osmotic stability o f erythrocytcs. Mechanical lysis of erythrocytes is a fluid flow is du e to the membrane shearing and depends on the strength of protein back bone. Thermal denaturation of spectrin, modification of membranes by f ormaldehyde and glutaric aldehyde, and decreasing the cell concentrati on increase the mechanical fragility of erythrocytes. Erythrocytes hav e the maximum mechanical strength at pH 6.7-7.2.