Scow R O, Blanchette-Mackie E J, Smith L C
Fed Proc. 1980 Jul;39(9):2610-7.
Fatty acids, monoacylglycerol, cholesterol, and phospholipids are taken up from blood by many different tissues. These substances, which are strongly amphipathic at physiological pH, are poorly soluble in water and neutral lipids (tyriacylglycerol nd cholesteryl ester). They are transported in blood as components of lipoprotein particles or, in the case of fatty acids, s monomers bound to albumin. Fatty acids derived from the diet are carried as triacylglycerol in chylomicrons and very low density lipoprpoteins (VLDL). Phospholipids and cholesterol absorbed from intestines are also transported in chylomicrons and VLDL. We propose that transport of fatty acids and monoacylglycerol from chylomicrons Tand VLDL) across capillary endothelium in extrahepatic tissues requires 1) conversion of chylomicron triacylglycerol to amphipathic lipids (fatty acids and monoacylglycerol) by lipoprotein lipase at the capillary surface, 2) location and lateral movement of ipolytic products in a continuous interface composed of the chylomicron surface film and the external leaflet of plasma and intracellular membranes of endothelial and parenchymal cells, and 3) removal of lipolytic products from the interface in endoplasmic reticulum where they are reesterified to traicylglycerol and accumulate between leaflets of endoplasmic reticulum. We suggest that cholesterol and phospholipids from chylomicrons, and fatty acids from plasma albumin, also cross capillary endothelium by lateral movement in cell membranes.
许多不同组织从血液中摄取脂肪酸、单酰甘油、胆固醇和磷脂。这些物质在生理pH值下具有很强的两亲性，在水中和中性脂质（三酰甘油和胆固醇酯）中溶解度很低。它们在血液中作为脂蛋白颗粒的成分运输，或者对于脂肪酸来说，作为与白蛋白结合的单体运输。饮食中来源的脂肪酸以三酰甘油的形式存在于乳糜微粒和极低密度脂蛋白（VLDL）中。从肠道吸收的磷脂和胆固醇也通过乳糜微粒和VLDL运输。我们提出，脂肪酸和单酰甘油从乳糜微粒（和VLDL）跨肝外组织的毛细血管内皮运输需要：1）脂蛋白脂肪酶在毛细血管表面将乳糜微粒三酰甘油转化为两亲性脂质（脂肪酸和单酰甘油）；2）水解产物在由乳糜微粒表面膜以及内皮细胞和实质细胞的血浆和细胞膜外小叶组成的连续界面中的定位和横向移动；3）在内质网中从界面去除水解产物，在那里它们被重新酯化为三酰甘油并在内质网小叶之间积累。我们认为，来自乳糜微粒的胆固醇和磷脂，以及来自血浆白蛋白的脂肪酸，也通过在细胞膜中的横向移动穿过毛细血管内皮。
