Biochemistry & Pharmacology: Open Access
Open Access

Abstract

Carboxylic Acids with Certain Molecular Structures Strengthen the Cell Membrane against Osmotic Pressure in Sheep Erythrocytes In Vitro

Hitoshi Mineo, Mikako Noji, Yukino Watanabe, Yukina Yoshikawa, Yuuka Ono and Naomi Iwayama

In sheep red blood cells (RBCs), considering osmotic fragility (OF) as an indicator, the reaction of monocarboxylic and dicarboxylic acids on membrane resistance to osmotic pressure were evaluated. Sheep RBCs were exposed to carboxylic acids at 0-100 mM in a buffer solution for 1 h and the 50% hemolysis was then determined by soaking in 0.1-0.8% NaCl solution. Although formic acid declined and n-caprylic acid increased OF, most of the monocarboxylic acids with straight hydrocarbon chains did not change OF in sheep RBCs. Whereas, all the tested dicarboxylic acids with straight hydrocarbon chains decreased OF with the degree of the decrease in OF dependent on the compound. Some monocarboxylic acids with branched or cyclic (including a benzene ring) hydrocarbon chains decreased OF with the degree of the decrease dependent on the number of carbons and form of branching in the hydrocarbon chain. Dicarboxylic acids with a cyclohexane ring or benzene ring decreased or tended to decrease OF with the degree of the decrease dependent on the position of the two carboxylic groups. 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 acid on the cell membrane as evaluated by the change in OF in sheep RBCs. It is speculated that the space composed of the acyl-chains of the phospholipids, into which hydrophobic hydrocarbons can enter to form a more rigid structure through their subsequent interaction, is an important factor related to the OF-decreasing effect of carboxylic acids.