STUDIES OF FACTORS REGULATING THE AGING OF HUMAN ERYTHROCYTES .1. ROLE OF PH AND OF DIVALENT-CATIONS

1. 1. Human erythrocytes incubated in vitro in a protein-free medium containing calcium and magnesium but without glucose, undergo a rapid process of ageing demonstrated by ATP depletion, discocyte-echinocyte transformation and membrane shedding. 2. 2. Lowering the pH from 7.2 to 6.8 increases the release of sialic acid-components from the membrane. 3. 3. In absence of glucose, calcium increases strongly this release that can be blocked by addition of a chelator. 4. 4. Erythrocytes incubated in heparinized plasma similarly loose sialic acid from the membrane but in small amounts because of the protective action of plasma factors. 5. 5. Loss of free sialic acid from the membrane is surprisingly little while the bulk is lost as bound to glycopeptides and to vesicles. © 1979.