Effect of tetracaine chlorhydrate on the mechanical properties of the erythrocyte membrane.

Pharmacologically active agents that locate in the cell membrane are useful tools to investigate the interactions taking place between its molecular components. In the present work, the effect of tetracaine chlorhydrate (Tc) on the membrane mechanical properties of intact and desialated erythrocytes was studied. Our results evince the complex interaction between the drug and the membrane structures. The effect of Tc on erythrocyte shape suggests that this drug locates in the inner hemilayer of the lipid bilayer. Since Tc also modifies osmotic fragility and mechanical properties ascribed to the cytoskeleton, it can be inferred that the lipid bilayer has an effect on the rheology of the membrane, in a direct or indirect way, in this case through the close interaction with the structural proteins. Moreover, our results support the hypothesis of a second localization of the drug in the membrane, i.e., as monovalent cations intercalated among the glycocalix sialic endings, where it generates an effect superimposed on that produced from its typical site in the lipid bilayer. Copyright 2001 Academic Press.