Changes In Erythrocyte Membrane Research Articles

Changes in erythrocyte membranes during preparation, as expressed by ATPase activity

During the preparation of membranes from human erythrocytes by osmotic lysis in 20 imosM Tris buffer at pH 7.6 there is a decrease in total ATPase activity and concomitantly a progressive alteration of the membrane (maximal at the fourth wash), as indicated by the exposure of (Na +,K +,Mg 2+)-ATPase activity. These changes are pronounced at pH 7.6 but occur to a much lesser extent at pH 5.8. Examination of calf and goat erythrocytes showed that these membranes are maximally altered (as indicated by ATPase activity) in the first hypotonic wash in the 20 T buffer, pH 7.6. Again a loss of total ATPase activity (units) was noted. These results emphasize some of the problems encountered in correct depiction of the characteristics of a membrane and provide an interesting avenue to further study on factors involved in the stability and behavior of these membranes.

Changes in erythrocyte membrane and autohaemolysis during in vitro incubation.

Summary. Spontaneous autohaemolysis occurs as sterile defibrinated blood is incubated at 37°C. This study was undertaken to identify the membrane changes which occurred during autohaemolysis and the effect upon these of supplementary glucose.After 24 hours of incubation the earliest membrane change recognized was the loss of small amounts of cholesterol; this occurred equally in incubations with and without added glucose. Spherocytes were prominent in incubations without added glucose but were infrequent when supplementary glucose was provided. During the second 24 hours of incubation cholesterol loss increased and phospholipids eluted from the cell surface. In this period of incubation cholesterol and phospholipid loss was less in incubations provided with supplementary glucose. The major individual phosphatides lecithin, sphingomyelin, phosphatidylethanolamine and phosphatidylserine were lost in proportion to their original concentration in the membrane. Membrane protein did not decrease as cell lipid loss occurred.