Article,
The effect of disaccharides on the transport of lipophilic ions in cell membranes studied by electrorotation
(2004)
Abstract
The disaccharide trehalose, a natural cryoprotectant, is increasingly being exploited in biomedicine as a very efficient stabilizer of frozen and dry macromolecules, membranes and whole cells. Valuable insight into the mechanisms by which trehalose protects cells can be obtained by studying its effects on the electrical and ion transport properties of cell membranes. In the present study, the binding and translocation of the lipophilic anion dipicrylamine (DPA) across the membrane of Jurkat lymphocytes (suspended in hypotonic trehalose- or sucrose-substituted media) were determined by means of electrorotation. From the rotation spectra of individual cells, not only the passive electrical properties of cell compartments but also the area-specific concentration of DPA adsorbed to the plasma membrane and its translocation rate constants were evaluated. The substitution of sucrose by trehalose increased significantly both the plasma membrane capacitance C-m and the adsorption of DPA to the plasma membrane, whereas the translocation rate of DPA across the membrane was slightly reduced. The high C-m value indicates that hypotonic stress did not cause any noticeable loss of membrane folds and microvilli in the presence of trehalose. The observed changes in the transport of DPA are consistent with the assumption that trehalose increased the dipole potential of the plasma membrane.
