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 mitochondria' 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 mu M) 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 mu M), but other bivalent cations (200 mu M 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.