Divalent cations and chlorpromazine can induce non-bilayer structures in phosphatidic acid-containing model membranes.
(1) The structural organization of aqueous dispersions of 1,2-dioleoylphosphatidic acid has been investigated by freeze-fracture electron microscopy in relation to variations in pH, divalent cations and the local anaesthetic chlorpromazine. (2) In the pH range 4--8 in the presence of 100 mM Na+, dioleoylphosphatidic acid is organized in bilayers. (3) At pH 6 and not at pH 4 and 8.5 addition of Ca2+, Mg2+, Mn2+ and chlorpromazine results in the formation of the hexagonal HII phase. (4) Ca2+ and chlorpromazine addition to mixed phosphatidylcholine-dioleoylphosphatidic acid bilayers at pH 6 results in the formation of lipidic particles.
D002118:Calcium; D002413:Cations, Divalent; D002746:Chlorpromazine; D005614:Freeze Fracturing; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers; D008081:Liposomes; D008274:Magnesium; D008345:Manganese; D008854:Microscopy, Electron; D008968:Molecular Conformation; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D013329:Structure-Activity Relationship
D002413:Cations, Divalent; D008051:Lipid Bilayers; D008081:Liposomes; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; D008345:Manganese; D008274:Magnesium; D002118:Calcium; D002746:Chlorpromazine