Schreier H
University of Florida College of Pharmacy, Department of Pharmaceutics, J. Hillis Miller Health Center, Gainesville 32610.
Life Sci. 1989;44(3):193-200. doi: 10.1016/0024-3205(89)90595-x.
The quantitative and qualitative interaction of liposomes with synaptosomes isolated from rat brain was examined using radiolabeled phospholipids and electron microscopy. Liposomes were prepared by sonication and detergent dialysis. Binding (adsorption) of radiolabeled phospholipid to synaptosomes was saturable when liposomes were in the liquid-crystalline state, were electrically neutral (egg-phosphatidylcholine), or carried increasing fractions (10:2 and 10:4 molar ratio) of negatively charged phosphatidic acid. Analysis using the Langmuir isotherm equation indicated a biphasic adsorption behavior. Adsorption increased with increasing temperature (4 degrees C and 37 degrees C). Binding was nonsaturable when liposomes were positively charged with stearylamine or composed of dimyristoylphosphatidylcholine and phosphatidylinositol (10:2 molar ratio). Due to the latter composition's solid state at 4 degrees C, temperature dependency was inverse. Electron micrographs revealed disc-shaped areas of adsorption that were free of integral membrane particles which appeared to form a condensed layer surrounding the areas of liposome adsorption. Following interaction with stearylamine-containing liposomes the vesicular structure of synaptosomes appeared largely destroyed. It is concluded that both liposome surface charge and membrane fluidity determine the extent of interaction with biological membranes.
利用放射性标记的磷脂和电子显微镜，研究了脂质体与从大鼠脑中分离出的突触体的定量和定性相互作用。脂质体通过超声处理和去污剂透析制备。当脂质体处于液晶态、呈电中性（卵磷脂）或携带增加比例（10:2和10:4摩尔比）的带负电荷的磷脂酸时，放射性标记的磷脂与突触体的结合（吸附）是可饱和的。使用朗缪尔等温线方程进行分析表明存在双相吸附行为。吸附随温度升高（4℃和37℃）而增加。当脂质体用硬脂胺带正电荷或由二肉豆蔻酰磷脂酰胆碱和磷脂酰肌醇（10:2摩尔比）组成时，结合是不饱和的。由于后一种组合物在4℃时为固态，温度依赖性是相反的。电子显微镜照片显示出无完整膜颗粒的盘状吸附区域，这些颗粒似乎形成围绕脂质体吸附区域的凝聚层。与含硬脂胺的脂质体相互作用后，突触体的囊泡结构似乎大部分被破坏。得出的结论是，脂质体表面电荷和膜流动性都决定了与生物膜相互作用的程度。
