Echinocyte formation induced by potential changes of human red blood cells

In isotonic 30 mM NaCl-saccharose solution, human red blood cells with intact membrane and normal inside ionic content (C-state) indicate a transmembrane potential between +30 mV (at pH 7.4) and +46 mV (at pH 5.1). After treatment with amphotericin B or nystatin as ionophores, a Donnan equilibrium (D-state) will be reached with the same potential at pH 5.1 but a sharp drop down to -20 mV will occur at pH 7.4. Concerning the erythrocyte shape at these states, a stomatocyte-echinocyte transformation takes place, in correlation with the potential shift. Stomatocytes formed at delta psi greater than +25 mV, echinocytes at delta psi less than +25 mV. At potentials lower than +5 mV, no further effect can be observed. This process is reversible. Neuraminidase treatment as well as outside EDTA do not influence this process significantly. Human serum albumin in concentrations of 2% stabilizes the stomatocytes.