Volume expansion of erythrocytes is not the only mechanism responsible for the protection by arginine-based surfactants against hypotonic hemolysis.

A novel arginine-based cationic surfactant N-benzoyl-arginine dodecylamide (Bz-Arg-NHC) was synthesized in our laboratory. In this paper we study the interaction of Bz-Arg-NHC with sheep and human red blood cells (SRBC and HRBC respectively) due to their different membrane physicochemical/biophysical properties. SRBC demonstrated to be slightly more resistant than HRBC to the hemolytic effect of the surfactant, being the micellar structure responsible for the hemolytic effect in both cases. Moreover, besides the hemolytic effect, a dual behavior was observed for the surfactant studied: Bz-Arg-NHC was also able to protect red blood cells against hypotonic lysis for HRBC in a wide range of surfactant concentrations. However, the degree of protection showed for SRBC was about 50% lower than for HBRC. In this regard, a remarkable volume expansion was evidenced only for SRBC treated with Bz-Arg-NHC, although no correlation with the antihemolytic potency (pAH) was found. On the contrary, our surfactant showed a greater pAH when human erythrocytes were submitted to hypotonic stress, with a low volume expansion, showing a higher amount of solubilized phospholipids in the supernatant when compared with SRBC behavior. Surface plasmon resonance measurements show the molecular interaction of the surfactant with lipid bilayers from HRBC and SRBC lipids, demonstrating that in the latter neither microvesicle release or lipid extraction occurred. Our results demonstrate that the volume expansion of erythrocytes is not the only mechanism responsible for the protection by surfactants against hypotonic hemolysis: volume expansion could be compensated via microvesicle release or by the extraction of membrane components upon collisions between red blood cells and surfactant aggregates depending on the membrane composition.