Magot T, Verneau C, Lutton C, Chevallier F
Ann Nutr Metab. 1985;29(3):147-59. doi: 10.1159/000176958.
Rats were conditioned to ingest a 15-gram dietary mixture, in a single daily meal, between 6:00 and 9:00 a.m. Labeled cholesterol was introduced into the organism through four different physiological routes: ingestion of 14C-cholesterol, injection of 14C-acetate, injection of red cells or plasma whose cholesterol was tritium-labeled. The specific radioactivities of free and esterified cholesterol, in the different plasma lipoproteins and in the major organs, were measured at various time spans after the introduction. The results revealed a different source of cholesterol in chylomicrons and VLDL discharged by the intestine: the chylomicrons would principally carry esterified cholesterol coming from the intestinal contents, while esterified cholesterol coming from the intestinal wall was found mainly in VLDL. The free cholesterol of these lipoproteins would initially have the same origin as esterified cholesterol but rapid free cholesterol exchanges would introduce precociously cholesterol coming from other structures. The results demonstrated the significant role of the intestine in cholesterol synthesis and revealed that of VLDL in the internal secretion of cholesterol by the intestine. Chylomicrons also appeared to play a significant role in this secretion, by way of exchanges between intestinal cells and chylomicrons in the process of formation. Finally, the results suggested the existence of esterified cholesterol transfers from HDL to lower density lipoproteins (chylomicrons, VLDL and possibly LDL).
大鼠被训练在每天上午6:00至9:00之间单次进食15克饮食混合物。通过四种不同的生理途径将标记的胆固醇引入机体：摄入14C-胆固醇、注射14C-乙酸盐、注射其胆固醇被氚标记的红细胞或血浆。在引入后不同时间段测量不同血浆脂蛋白和主要器官中游离胆固醇和酯化胆固醇的比放射性。结果显示，肠道排出的乳糜微粒和极低密度脂蛋白（VLDL）中的胆固醇来源不同：乳糜微粒主要携带来自肠内容物的酯化胆固醇，而来自肠壁的酯化胆固醇主要存在于VLDL中。这些脂蛋白的游离胆固醇最初与酯化胆固醇来源相同，但快速的游离胆固醇交换会过早引入来自其他结构的胆固醇。结果证明了肠道在胆固醇合成中的重要作用，并揭示了VLDL在肠道胆固醇内分泌中的作用。乳糜微粒在该分泌过程中似乎也起重要作用，通过在形成过程中肠细胞与乳糜微粒之间的交换。最后，结果提示存在从高密度脂蛋白（HDL）到低密度脂蛋白（乳糜微粒、VLDL以及可能的低密度脂蛋白）的酯化胆固醇转移。
