Steinmetz A, Schwarz S, Richter G
Zentrum Innere Medizin, Klinikum, Philipps-Universität Marburg, BRD.
Infusionsther Transfusionsmed. 1992 Feb;19(1):32-6.
Apolipoprotein (apo) E plays a key role in chylomicron metabolism as a ligand for their uptake via the apo B/E- and apo E receptor into the liver. Apo E is not primarily synthesized with chylomicrons but is postprandially transferred to chylomicrons during lipolysis in plasma from high density lipoproteins (HDL). As triglyceride-/phospholipid emulsions given intravenously acquire apolipoproteins in plasma, we set out to investigate a possible transfer of apo E to these artificial lipoproteins and its role during their further metabolism. To this end healthy normolipemic volunteers and carriers of the frequent apo E3/3 phenotype were infused lipid emulsions. The lipoprotein-distribution of apo E during MCT and LCT infusions was monitored over four hours. Infusion of MCT and LCT resulted in a substantial transfer of apo E from HDL to triglyceride rich lipoproteins. During MCT infusion the transfer of apo E seemed to occur more rapidly than during LCT infusion. This could be one of the reasons for the faster metabolism of MCT over LCT. Plasma levels of apo E also decreased significantly during infusion of triglyceride/phospholipid emulsions in accordance with the role of apo E as a ligand for the uptake of the artificial particles into the liver.
载脂蛋白（apo）E作为乳糜微粒通过apo B/E受体和apo E受体摄取进入肝脏的配体，在乳糜微粒代谢中起关键作用。apo E并非主要与乳糜微粒一起合成，而是在餐后血浆中高密度脂蛋白（HDL）的脂解过程中转移至乳糜微粒。由于静脉注射的甘油三酯/磷脂乳剂在血浆中获得载脂蛋白，我们着手研究apo E向这些人工脂蛋白的可能转移及其在进一步代谢中的作用。为此，我们对健康血脂正常的志愿者和常见apo E3/3表型携带者输注脂质乳剂。在4小时内监测中链甘油三酯（MCT）和长链甘油三酯（LCT）输注期间apo E的脂蛋白分布。MCT和LCT输注导致apo E从HDL大量转移至富含甘油三酯的脂蛋白。MCT输注期间apo E的转移似乎比LCT输注期间更快。这可能是MCT代谢比LCT更快的原因之一。根据apo E作为人工颗粒摄取进入肝脏的配体的作用，在甘油三酯/磷脂乳剂输注期间血浆apo E水平也显著降低。
