Ethanol Improves Decreased Filterability of Human Red Blood Cells Through Modulation of Intracellular Signaling Pathways

Abstract

Deformability of red blood cells (RBCs) is one of the most important factors in maintaining the microcirculation system. In vitro studies have revealed that ethanol seriously impairs the deformability of RBCs at concentrations far higher than those easily achievable in the blood after alcohol consumption. We examined the effect of ethanol on deformability at the physiologically achievable concentrations. To impair deformability quantitatively, washed RBCs from healthy young male volunteers were mechanically stressed by being injected rapidly through a fine needle. The deformability of RBCs was evaluated by measuring the filterability through a nickel mesh filter. The activities of protein kinase A and protein kinase C in RBCs were measured by the ELISA method using an antibody for the phosphorylated substrate of the kinases. Ethanol exhibited a biphasic effect on the mechanically impaired filterability of human RBCs, that is, an improvement at concentrations from 0.02% to 0.2% (v/v) and a marked deterioration at 0.5% and higher. Without mechanical stress, ethanol decreased filterability at concentrations of 0.5% and higher. Ethanol increased the protein kinase A and protein kinase C activities of the mechanically stressed RBCs at concentrations of 0.02% and higher and those of the RBCs without mechanical stress at concentrations of 0.05% and higher. The present results suggest a beneficial effect of ethanol on blood rheology at concentrations that are physiologically achievable in the blood and indicate the importance of intracellular signaling pathways in regulating the deformability of RBCs.