Effect of ionic strength and outer surface charge on the mechanical stability of the erythrocyte membrane: a linear hydrodynamic analysis.

A linear hydrodynamic analysis in normal modes has been developed for a membrane model that simulated the erythrocytes membrane. The characteristic dispersion equation was obtained by solving the linearized dynamic equations. Values of the parameters related to the erythrocyte membrane were used to obtain the critical stability curves as a function of cell surface electric charge and suspending phase ionic strength. According to this model, the mechanical stability of the membrane increases with the decrease of the negative charge value on the outer membrane surface. The conclusion is that the transmembrane-potential and surface-charge changes that follow the reduction in ionic strength were responsible for the stability increase observed in previously reported experiments on heated erythrocytes.