Carboxylic Acids with Certain Molecular Structures Decrease Osmotic Fragility against Osmotic Pressure in Cattle Erythrocytes In Vitro: Appearance of a Wedge-like Effect Similar to RBCs in Other Animal Species

Osmotic fragility (OF) in red blood cells (RBCs) is a useful tool for evaluating the actions of various chemicals on the cell membrane in vitro. The effects of monocarboxylic and dicarboxylic acids on OF were evaluated in cattle RBCs. Isolated cattle RBCs were immersed in various carboxylic acids at 0-100 mM in a buffer solution for 1 hr and the 50% hemolysis was then determined by soaking in 0.1-0.8% NaCl solution. Although n-caprylic acid at 100 mM induced hemolysis, the other monocarboxylic acids possessing straight hydrocarbons did not affect OF. The dicarboxylic acids possessing straight hydrocarbons, except for glutaric acid, decreased OF in a dose-dependent manner. Some monocarboxylic acids with branched hydrocarbons tended to decrease OF, but these changes were not statistically significant. Although cyclopentanecarboxylic and cyclohexanecarboxylic acids at 100 mM decreased OF, other monocarboxylic acids with cyclic hydrocarbons did not affect OF. Among the dicarboxylic acids with cyclic hydrocarbons tested, only 1,2-cyclohexanedicarboxylic acid and phthalic acid with a benzene ring significantly decreased OF. There is no clear correlation between the effect of monocarboxylic or dicarboxylic acids on OF, and their partition coefficients. Thus, the partition coefficient is not a suitable parameter for explaining the effect of both groups of carboxylic acids on OF in cattle RBCs. With regard to the effect of monocarboxylic acids on OF, although an increase in OF was demonstrated in rat RBCs, no effect or rather a decrease in OF was demonstrated in cattle RBCs, similar to the results observed for guinea pig and sheep RBCs. With regard to the effect of dicarboxylic acids, decreases in OF were already demonstrated in rat, guinea pig and sheep RBCs. We have proposed that dicarboxylic acids exhibit a common stabilizing effect on the RBC membrane in various animals, which we termed a “wedge-like effect”. We clarified that cattle RBCs also show a similar OF response to dicarboxylic acids in this experiment.