Structural changes in bilayer membranes by multivalent ions

Formation of microlenses, a reduction in thickness, and a change in mechanical properties have been observed when Ca2+ or other multivalent ions are added to bathing solutions of Mueller-Rudin membranes of acidic phospholipids. The observations are interpreted as an extrusion of residual solvent from the hydrocarbon core of the bilayer due to changes in packing imposed by the reduction of electrostatic repulsion of the head groups. © 1976.