Correlation between Changes of Shape and of Osmotic Resistance of Human Erythrocytes induced by Amphipathic Drugs

Abstract

Many of the amphipathic drugs tested, which induced shape changes in intact human erythrocytes, produced biphasic effects on hypotonic hemolysis in a similar concentration range, protection at low concentrations and stimulation at higher concentrations. Drugs which induced membrane exvagination and invagination, respectively, showed the same type of effect on osmotic resistance. When 2 drugs of either the exvaginator or invaginator type were present together in a hemolyzing medium, their effects on osmotic resistance appeared to be additive, as were their effects on cell shape. When an exvaginator and an invaginator were present together, their effects, both on osmotic resistance and cell shape, seemed to be antagonistic. These drugs may effect an asymmetric expansion of the membrane lipid bilayer due to asymmetric distribution of the drugs incorporated into the membrane.