Johnson F L, Swift L L, Rudel L L
J Lipid Res. 1987 May;28(5):549-64.
Perfusate apoB-100-containing lipoproteins from the isolated, perfused livers of African green monkeys consist of significant amounts of d greater than 1.006 g/ml particles in addition to very low density lipoproteins (VLDL). Distinguishing characteristics of these perfusate lipoproteins are the relative abundance of surface lipids and deficiency of core lipids. The present studies were performed to determine the likelihood that the d greater than 1.006 g/ml perfusate lipoproteins are secretion products instead of products of post-secretory modification (e.g., lipolysis) of secreted VLDL. [14C]Leucine from the perfusate became incorporated into the apoB of each of the perfusate lipoprotein classes to a similar extent in both recirculating and nonrecirculating perfusions. When endogenously radiolabeled perfusate VLDL from one liver was recirculated through a second liver, only about 15% of the radiolabeled protein appeared in the d greater than 1.006 g/ml fraction. The particle morphology and the cholesterol and apoB distribution between VLDL and d greater than 1.006 g/ml fractions were similar in recirculating and nonrecirculating perfusions. A Golgi apparatus-rich fraction was isolated from the homogenates of fresh liver samples and the isolated Golgi VLDL and d greater than 1.006 g/ml lipoproteins exhibited morphologic evidence of extra surface material analogous to that seen in perfusate. Taken together, these data support the possibility that significant amounts of d greater than 1.006 g/ml lipoproteins, many with surface-rich properties, are nascent, secretory products of the primate liver. The low level of lecithin:cholesterol acyltransferase (LCAT) in this perfusion system appears to permit detection of these secretion products and it is significant to note that the perfusate lipoprotein profile, which is unlike that of normal plasma, is similar to that of LCAT-deficient patients.
来自非洲绿猴离体灌注肝脏的灌注液中含载脂蛋白B-100的脂蛋白，除极低密度脂蛋白（VLDL）外，还包含大量密度大于1.006 g/ml的颗粒。这些灌注液脂蛋白的显著特征是表面脂质相对丰富而核心脂质缺乏。进行本研究以确定密度大于1.006 g/ml的灌注液脂蛋白是分泌产物而非分泌的VLDL经分泌后修饰（如脂解）产物的可能性。在循环灌注和非循环灌注中，灌注液中的[14C]亮氨酸以相似的程度掺入到各灌注液脂蛋白类别的载脂蛋白B中。当来自一个肝脏的内源性放射性标记的灌注液VLDL通过第二个肝脏再循环时，只有约15%的放射性标记蛋白出现在密度大于1.006 g/ml的组分中。在循环灌注和非循环灌注中，VLDL与密度大于1.006 g/ml组分之间的颗粒形态以及胆固醇和载脂蛋白B分布相似。从新鲜肝脏样品的匀浆中分离出富含高尔基体的组分，分离出的高尔基体VLDL和密度大于1.006 g/ml的脂蛋白表现出额外表面物质的形态学证据，类似于在灌注液中所见。综上所述，这些数据支持了大量密度大于1.006 g/ml的脂蛋白（许多具有富含表面的特性）是灵长类动物肝脏新生分泌产物的可能性。该灌注系统中卵磷脂胆固醇酰基转移酶（LCAT）水平较低似乎使得能够检测到这些分泌产物，值得注意的是，灌注液脂蛋白谱不同于正常血浆，与LCAT缺乏患者的相似。
