EFFECT OF OKADAIC ACID ON THE RHEOLOGICAL PROPERTIES OF HUMAN ERYTHROCYTE-MEMBRANES

The unique mechanical properties of mammalian red cell membranes are c onferred by a specialized submembrane reticulum of proteins referred t o as the membrane skeleton. Studies performed in vitro have suggested that the phosphorylation status of many skeletal proteins could be cri tical to the structure and function of the erythrocyte membrane. Syste matic studies were performed to correlate skeletal protein phosphoryla tion status with membrane properties such as deformability and mechani cal resistance to shear stress. Okadaic acid (OA), an inhibitor of ser ine-threonine phosphatases was used to obtain in situ hyperphosphoryla tion of all the major skeletal phosphoproteins. To analyse the cellula r rheology of erythrocyte, an ektacytometer was used to study the defo rmability of red cells and the mechanical stability of erythrocyte mem branes. Using this technique, a dose response relationship was found b etween the increase in phosphorylation of the major skeletal proteins and the decrease in the mechanical stability of the erythrocyte membra ne. In contrast, erythrocyte deformability was not affected, confirmin g that erythrocyte deformability and stability are two distinct membra ne properties.