Beltz W F, Kesäniemi Y A, Howard B V, Grundy S M
J Clin Invest. 1985 Aug;76(2):575-85. doi: 10.1172/JCI112009.
To quantify more precisely the metabolism of apolipoprotein B (apo B) in human beings, an integrated model was developed for the analysis of the isotope kinetics of apo B in very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL), and low density lipoproteins (LDL). The experimental basis for model development was a series of 30 triple-isotope studies in which patients received autologous 131I-VLDL, 125I-IDL, and [3H]glycerol as a precursor of VLDL triglycerides. The currently proposed model contains the following components: (a) a VLDL delipidation cascade that has a variable number of subcompartments, (b) a slowly catabolized pool of VLDL, (c) an IDL compartment consisting of two closely connected subcompartments, one of which is outside the immediate circulation, and (d) a two-compartment subsystem for LDL. Because mass data indicate that not all VLDL were converted to LDL, the model allows for irreversible removal of apo B from VLDL (or IDL) subsystems. It accounts for apparent "direct" input of LDL by postulating an early, rapidly metabolized compartment of VLDL that is converted directly to IDL. The model appears to be consistent with specific activity curves from the current triple-isotope studies and with present concepts of lipoprotein physiology; it also can be used to quantify pathways of lipoprotein apo B transport in normal and abnormal states.
为了更精确地量化人类载脂蛋白B（apo B）的代谢，我们开发了一个综合模型，用于分析极低密度脂蛋白（VLDL）、中间密度脂蛋白（IDL）和低密度脂蛋白（LDL）中apo B的同位素动力学。模型开发的实验基础是一系列30项三重同位素研究，其中患者接受自体131I-VLDL、125I-IDL和[3H]甘油作为VLDL甘油三酯的前体。目前提出的模型包含以下组成部分：（a）一个具有可变数量子隔室的VLDL脱脂级联反应，（b）一个缓慢分解代谢的VLDL池，（c）一个由两个紧密相连的子隔室组成的IDL隔室，其中一个位于直接循环之外，以及（d）一个用于LDL的双隔室子系统。由于质量数据表明并非所有VLDL都转化为LDL，该模型允许从VLDL（或IDL）子系统中不可逆地去除apo B。它通过假设一个早期快速代谢的VLDL隔室直接转化为IDL来解释LDL的明显“直接”输入。该模型似乎与当前三重同位素研究的比活曲线以及目前的脂蛋白生理学概念一致；它还可用于量化正常和异常状态下脂蛋白apo B的转运途径。
