title: Barrier characteristics of membrane model systems containing unsaturated phosphatidylethanolamines.
abstract: The barrier characteristics of membrane model systems containing unsaturated phosphatidylethanolamines have been investigated. (1) At increasing temperatures 18:1c/18:lc-phosphatidylethanolamine liposomes lose their permeability barrier for K+ as a consequence of the transition from a lamellar to a hexagonal orientation as detected by 31P-NMR and freeze-fracturing electron microscopy. (2) Introduction of 18:1c/18:1c-phosphatidylcholine in the 18:1c/18:1c-phosphatidylethanolamine lipid system stabilizes the bilayer structure and the permeability barrier for K+ and glucose while cholesterol destabilizes. (3) Upon heating of the investigated 18:1c/18:1c-phosphatidylcholine-18:1c/18:1c-phosphatidylethanolamine-(cholesterol) mixtures, structures are formed which give rise to isotropic 31P-NMR signals and which on the basis of freeze-fracture pictures are interpreted as sponge-like structures. Lowering the temperature results in restoration of the barrier function of the lipid structures.
mesh_terms: D005614:Freeze Fracturing; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy; D008854:Microscopy, Electron; D010539:Permeability; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D011188:Potassium; D013696:Temperature
chemical_list: D008081:Liposomes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D011188:Potassium