Hayward D, Schiff D, Fedunec S, Chan G, Davis P J, Poznansky M J
Biochim Biophys Acta. 1986 Aug 7;860(1):149-53. doi: 10.1016/0005-2736(86)90509-2.
The possibility that bilirubin can diffuse through lipid bilayers is investigated with liposomes prepared from dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylcholine (egg PC) with 22 mole percent cholesterol, and a lipid extract preparation from N115 neuroblastoma cells. Liposomes were prepared with internalized bilirubin and bovine or human serum albumin, and bilirubin efflux into an exogenous solution of human serum albumin was measured. Efflux from DPPC liposomes was significantly higher above the phase transition temperature than below it. This change was dependent on the lipid undergoing a phase transition and could not be accounted for by 6 K change in temperature. Maximum bilirubin efflux from egg PC-cholesterol liposomes was found to depend on the relative internal and external albumin pools, suggesting an equilibrium distribution of bilirubin between them. These observations demonstrate that bilirubin can diffuse freely through these lipid membranes.
利用由二棕榈酰磷脂酰胆碱（DPPC）、含有22摩尔百分比胆固醇的鸡蛋磷脂酰胆碱（鸡蛋PC）以及从N115神经母细胞瘤细胞制备的脂质提取物制备的脂质体，研究胆红素能否扩散穿过脂质双层。制备含有内化胆红素和牛或人血清白蛋白的脂质体，并测定胆红素向人血清白蛋白外源溶液中的流出情况。高于相变温度时，DPPC脂质体的流出量显著高于低于相变温度时。这种变化取决于发生相变的脂质，且不能用温度6K的变化来解释。发现鸡蛋PC - 胆固醇脂质体的最大胆红素流出量取决于相对的内部和外部白蛋白池，表明胆红素在它们之间呈平衡分布。这些观察结果表明胆红素可以自由扩散穿过这些脂质膜。
