Green M H, Massaro E R, Green J B
Am J Clin Nutr. 1984 Jul;40(1):82-94. doi: 10.1093/ajcn/40.1.82.
The potential contribution of the metabolism of absorptive lipoproteins to effects of dietary cholesterol and saturated (versus polyunsaturated) fat on plasma lipids and lipoproteins was studied in rats. Recipients were fed either a commercial stock diet, a low fat/cholesterol-free semipurified diet with a neutral P/S ratio, or one of two high fat/cholesterol-containing diets that had a high (4.6) or low (0.2) P/S ratio. Chylomicrons and intestinal very low-density lipoproteins labeled with 3H-oleic acid and/or 14C-cholesterol were isolated from donor rats receiving the high or low P/S ratio oil and were injected into recipients. Data on plasma disappearance and hepatic recovery of labels were analyzed by compartmental analysis. A multicompartmental model was required to fit these data and included steps interpreted to correspond to activation of newly secreted intestinal lipoproteins; delipidation on capillary endothelia by lipoprotein lipase, with transfer of cholesterol to other lipoproteins and tissue uptake of cholesterol and fatty acids; hepatic clearance of remnants; and secretion of lipoproteins by the liver. Metabolic state of the recipients (especially plasma triglyceride concentrations) had a greater influence on the rate of chylomicron turnover than did the source of donor chylomicrons, although saturated chylomicrons tended to be metabolized more slowly than polyunsaturated ones. For recipients fed the commercial stock diet and injected with saturated (versus polyunsaturated) chylomicrons, the mechanistic model predicted an increased retention of triglycerides during remnant formation, and thus an increased delivery of triglyceride to the liver. A consequent elevation in hepatic production of very low-density lipoprotein triglycerides may be related to the observed slower clearance of chylomicrons and increased plasma lipid levels in rats fed saturated fat and cholesterol.
在大鼠中研究了吸收性脂蛋白代谢对膳食胆固醇和饱和（相对于多不饱和）脂肪对血浆脂质和脂蛋白影响的潜在作用。实验对象分别喂食商业储备饲料、中性P/S比的低脂/无胆固醇半纯化饲料，或两种高脂/含胆固醇饲料之一，其P/S比高（4.6）或低（0.2）。从接受高或低P/S比油的供体大鼠中分离出用3H-油酸和/或14C-胆固醇标记的乳糜微粒和肠道极低密度脂蛋白，并注入受体大鼠体内。通过房室分析来分析标记物在血浆中的消失和肝脏中的回收数据。需要一个多房室模型来拟合这些数据，该模型包括一些步骤，这些步骤被解释为对应于新分泌的肠道脂蛋白的激活；脂蛋白脂肪酶在毛细血管内皮上的脱脂作用，胆固醇转移到其他脂蛋白以及胆固醇和脂肪酸的组织摄取；肝脏对残余物的清除；以及肝脏分泌脂蛋白。受体的代谢状态（尤其是血浆甘油三酯浓度）对乳糜微粒周转速率的影响比供体乳糜微粒的来源更大，尽管饱和乳糜微粒的代谢往往比多不饱和乳糜微粒更慢。对于喂食商业储备饲料并注射饱和（相对于多不饱和）乳糜微粒的受体，机理模型预测在残余物形成过程中甘油三酯的保留增加，从而增加甘油三酯向肝脏的输送。由此导致的肝脏极低密度脂蛋白甘油三酯产生的升高可能与喂食饱和脂肪和胆固醇的大鼠中观察到的乳糜微粒清除减慢和血浆脂质水平升高有关。
