Effect of oxidative stress on membrane phospholipid and protein organization in human erythrocytes

Membrane phospholipid and protein organization was studied in intact human erythrocytes exposed to phenylhydrazine, an oxidative agent inducer. The evaluation of the membrane phospholipid and protein organization was carried out in terms of asymmetric distribution across the membrane bilayer for the phospholipids, and in terms of accessibility of cleavable sites present on the outer membrane surface for the proteins. Treatment of phenylhydrazine-exposed erythrocytes either with bee venom phospholipase A2 or with trinitrobenzenesulfonic acid indicated that phosphatidylserine (PS), which is the only phospholipid not formally present on the outer leaflet of the membrane, was translocated to the outer surface of the cell membrane. The extent of this phenomenon was directly proportional to the concentration of the oxidant having a peak value at 0.1 mM. Phosphatidylcholine and phosphatidylethanolamine conserved their original distribution across the erythrocyte membrane throughout the study. The oxidant, at a dose which did not induce any modification of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis cytoskeleton membrane protein pattern, did not provoke any alteration of the membrane protein surface architecture, although the translocation of PS to the membrane outer leaflet in intact erythrocytes was present.