Carmaniu S, Herrera E
Rev Esp Fisiol. 1979 Dec;35(4):461-6.
The in vivo formation of labelled very low density lipoproteins (VLDL) from (U-14C)-glycerol, (2-3H)-glycerol and (1-14C)-palmitate was studied in fed female rats. The rate of disappearance of radioactivity from plasma after the i.v. injection with these tracers was similar for (U-14C)-glycerol and (1-14C)-palmitate. With (2-3H)-glycerol, plasma radioactivity at 10 min was lower than with the other substrates although it did not change thereafter. A certain proportion of radioactivity administered as glycerol appeared in plasma lipids, mainly in the VLDL glyceride glycerol fraction, although when (U-14C)-glycerol was the substrate, a considerable portion also appeared in the esterified fatty acids of these lipoproteins. When using (1-14C)-palmitate, practically all the circulating labelled esterified fatty acids appeared in the VLDL fraction, while the labelled free fatty acids appeared in lipoprotein of higher density, presumable free fatty acid-albumin complexes. This data is discussed in terms of the role of the liver in the rapid, continuous cycling of these substrates to yield VLDL-glycerides for their extrahepatic utilization.
在喂食后的雌性大鼠中研究了由（U-14C）-甘油、（2-3H）-甘油和（1-14C）-棕榈酸酯体内形成标记极低密度脂蛋白（VLDL）的情况。静脉注射这些示踪剂后，血浆中放射性的消失速率对于（U-14C）-甘油和（1-14C）-棕榈酸酯是相似的。对于（2-3H）-甘油，10分钟时的血浆放射性低于其他底物，不过此后没有变化。作为甘油给予的一定比例的放射性出现在血浆脂质中，主要在VLDL甘油三酯甘油部分，尽管当（U-14C）-甘油作为底物时，相当一部分也出现在这些脂蛋白的酯化脂肪酸中。当使用（1-14C）-棕榈酸酯时，几乎所有循环的标记酯化脂肪酸都出现在VLDL部分，而标记的游离脂肪酸出现在密度更高的脂蛋白中，推测是游离脂肪酸-白蛋白复合物。根据肝脏在这些底物快速、持续循环以产生VLDL甘油三酯用于肝外利用中的作用来讨论这些数据。
