Membrane damage model of lipid peroxidation, using carboxyfluorescein enveloping liposome

羧基荧光素（CF）包膜脂质体作为生物膜的物理化学损伤模型，用于脂质过氧化的研究。膜损伤的程度可以通过测量受损脂质体与自由基引发剂相互作用后释放的CF的荧光强度来评估。同时进行的硫代巴比妥酸活性物质（TBARS）试验证实了脂质过氧化过程。三种类型的cf包膜脂质体，即含有多不饱和脂肪酸的大豆磷脂酰胆碱（SPC），含有饱和脂肪酸的双棕榈酰磷脂酰胆碱（DPPC）和大豆磷脂酰胆碱加α -生育酚，暴露于已知的自由基引发剂，硝酸三乙酸铁和还原剂（半胱氨酸，还原型谷胱甘肽或抗坏血酸）。用荧光分光光度计测定过氧化脂质体中CF的释放量。在SPC脂质体中观察到CF的高释放和高水平的TBARS，而在DPPC和α -生育酚插入的SPC脂质体中则没有。该脂质体模型优于传统的红细胞溶血模型有以下几个原因：(1)膜的成分是明确的；(2) CF不是自由基引发剂，而血红蛋白是潜在的自由基引发剂；(3)根据实验目的，膜组分可以很容易地改变。

A Carboxyfluorescein (CF) -enveloping liposome is presented as a physicochemical damage model of the biomembrane for the study of lipid peroxidation. The degree of membrane damage may be assessed by measurement of the fluorescence intensity of CF released from damaged liposomes after the interaction between the liposomal membrane and a radical initiator. The process of lipid peroxidation was biochemically confirmed by the thiobarbituric acidreactive substances (TBARS) test done simultaneously. Three types of CF-enveloping liposomes, i.e., soybean phosphatidylcholine (SPC) containing polyunsaturated fatty acid, dipalmitoylphosphatidylcholine (DPPC) containing saturated fatty acid, and soybean phosphatidylcholine plus alpha-tocopherol, were exposed to a known radical initiator, ferric nitrilotriacetate with a reductant (either cysteine, reduced form glutathione, or ascorbic acid). The release of CF from the peroxidized liposome was measured with a fluorospectrophotometer. A high release of CF and a high level of TBARS were seen in the SPC liposomes, but not in the DPPC and alpha-tocopherol-inserted SPC liposomes. This liposome model is superior to the conventional red cell hemolysis model for several reasons : (1) the constituents of the membrane are defined ; (2) CF is not a radical initiator, whereas hemoglobin is a potential radical initiator ; and (3) the membrane components can be easily changed depending on the purpose of the experiment.