Effect of okadaic acid on the rheological properties of human erythrocyte membranes

Abstract

The unique mechanical properties of mammalian red cell membranes are conferred by a specialized submembrane reticulum of proteins referred to as the membrane skeleton. Studies performed in vitro have suggested that the phosphorylation status of many skeletal proteins could be critical to the structure and function of the erythrocyte membrane. Systematic studies were performed to correlate skeletal protein phosphorylation status with membrane properties such as deformability and mechanical resistance to shear stress. Okadaic acid (OA), an inhibitor of serine-threonine phosphatases was used to obtain in situ hyperphosphorylation of all the major skeletal phosphoproteins. To analyse the cellular rheology of erythrocyte, an ektacytometer was used to study the deformability of red cells and the mechanical stability of erythrocyte membranes. Using this technique, a dose response relationship was found between the increase in phosphorylation of the major skeletal proteins and the decrease in the mechanical stability of the erythrocyte membrane. In contrast, erythrocyte deformability was not affected, confirming that erythrocyte deformability and stability are two distinct membrane properties.