Palmitic Acid Induces the Opening of a Ca2+-Dependent Pore in the Plasma Membrane of Red Blood Cells: The Possible Role of the Pore in Erythrocyte Lysis

Earlier we found that in the presence of Ca²⁺ palmitic acid (Pal) increases the nonspecific permeability of artificial (planar and liposomal) membranes and causes permeabilization of the inner mitochondrial membrane. An assumption was made that the mechanism of Pal/Ca²⁺-induced membrane permeabilization relates to the Ca²⁺-induced phase separation of Pal and can be considered as formation of fast-tightening lipid pores due to chemotropic phase transition in the lipid bilayer. In this article, we continue studying this pore. We have found that Pal plus Ca²⁺ permeabilize the plasma membrane of red blood cells in a dose-dependent manner. The same picture has been revealed for stearic acid (20 μM) but not for myristic and linoleic acids. The Pal-induced permeabilization of erythrocytic membranes can also occur in the presence of Ba²⁺ and Mn²⁺ (200 μM), but other bivalent cations (200 μM Mg²⁺, Sr²⁺, Ni²⁺, Co²⁺) are relatively ineffective. The formation of Pal/Ca²⁺-induced pores in the erythrocytic membranes has been found to result in the destruction of cells.