Transmembrane movement of cholesterol in human erythrocytes.

Publisher Website
Google Scholar
Abstract
The exchange of cholesterol between radioactively labeled plasma and human erythrocytes was studied. Using [3H]cholesterol and [14C]cholesterol exchanged sequentially into the cells and back out into unlabeled plasma, transmembrane movement of cholesterol occurred with a half-time that was either less than 50 min or greater than 10 days. To obtain further information about the transmembrane movement of cholesterol, a technique for exposure of the cytoplasmic surface of erythrocyte membranes was used. This method involved the ionic attachment of erythrocytes to derivatized glass beads followed by disruption of the cells, leaving the beads covered by membrane with the cytoplasmic surface exposed. [3H]Cholesterol was exchanged into intact erythrocytes which then were attached to beads. The beads with attached membrane were incubated with phospholipid-cholesterol vesicles and the exchange of cholesterol between the membrane cytoplasmic surface and vesicles was studied. [3H]Cholesterol was present at the cytoplasmic surface, indicating that transmembrane movement of cholesterol had occurred within the 2.5 h required to complete the experiment. The more rapid rate of transmembrane cholesterol movement is probably the one that applies.