Critical temperatures for the interaction of free fatty acids with the erythrocyte membrane

Abstract

Non-esterified long-chain fatty acids reduce the extent of hypotonic hemolysis at a certain low concentration range but cause hemolysis at higher concentrations. This biphasic behavior was investigated at different temperatures (0–37°C) for lauric (12:0), myristic (14:0), palmitoleic (16:1), oleic ( cis-18:1) and elaidic ( trans-18:1) acids. The results are summarized as follows: (A) the fatty acids examined exhibit a high degree of specificity in their thermotropic behavior; (B) oleic acid protects against hypotonic hemolysis event at the highest concentrations, up to 15°C, when it becomes hemolytic, but only in a limited concentration range; (C) elaidic acid does not affect the osmotic stability of erythrocytes up to 20°C, when it starts protecting: above 30°C, it becomes hemolytic at the highest concentrations; (D) palmitoleic acid is an excellent protecting agent at all temperatures in a certain concentration range, becoming hemolytic at higher concentrations; (E) lauric acid protects up to 30°C and becomes hemolytic only in a limited concentration range; myristic acid exhibits an extremely unusual behavior at 30 and 37°C by having alternating concentration ranges of protecting and hemolytic effects; (G) there is a common critical temperature for hemolysis at 30°C for saturated and trans-unsaturated fatty acids; (H) the initial slope of Arrhenius plots of percent hemolysis at the concentration of maximum protection is negative for cis-unsaturated fatty acids and positive for saturated and trans-unsaturated fatty acid.