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
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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.
KeywordsPalmitic acid Calcium Lipid pore Erythrocyte
Free fatty acids
We are grateful to Dr. Natalia Venediktova (Institute of Theoretical and Experimental Biophysics RAS, Russia) for technical assistance in the preparation of SRB-loaded erythrocytes. This work was supported by a grant from the Russian Foundation for Basic Research, to K. N. B. (09-04-01024a), and the program Development of High School Scientific Potential from the Russian Ministry for Education, to G. D. M. (3840).
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