title: Membrane effects of aminoglycoside antibiotics measured in liposomes containing the fluorescent probe, 1-anilino-8-naphthalene sulfonate.
abstract: The mechanism of membrane disturbance by aminoglycoside antibiotics was investigated in liposomes containing the fluorescent probe, 1-anilino-8-naphthalene sulfonate (ANS). Liposomes of PC and different anionic phospholipids (1:1 to 15:1 molar ratios) were challenged with aminoglycosides in the presence of low (1 microM) and high (3 mM) concentrations of calcium. Liposomes containing PIP2 showed the greatest drug-induced changes in ANS fluorescence in the presence of high and low concentrations of calcium and at all PC:PIP2 molar ratios tested. Liposomes containing other anionic phospholipids (PS, PI and PIP) were not reactive toward aminoglycosides in the presence of 3 mM calcium or when the ratio of PC to anionic lipid was increased to 10:1. The aminoglycoside-induced changes of ANS fluorescence were not due to any changes in the emission spectrum of ANS, nor to changes in quantum yield, nor to a change in the binding affinity of ANS. It is concluded that a specific aminoglycoside-PIP2 interaction results in phase separation of PC and PIP2 and thus increases the number of available ANS binding sites in PC:PIP2 liposomes.
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000817:Anilino Naphthalenesulfonates; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D005453:Fluorescence; D005839:Gentamicins / Q000494:pharmacology; D008051:Lipid Bilayers / Q000032:analysis*; D008081:Liposomes / Q000032:analysis; D010713:Phosphatidylcholines / Q000032:analysis; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000032:analysis
chemical_list: D000617:Aminoglycosides; D000817:Anilino Naphthalenesulfonates; D000900:Anti-Bacterial Agents; D005839:Gentamicins; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D002118:Calcium