Green M H, Green J B
Atherosclerosis. 1983 Feb;46(2):181-94. doi: 10.1016/0021-9150(83)90109-0.
Lipid absorption was studied in non-fasting thoracic lymph duct-cannulated rats receiving continuous intraduodenal infusions of oils varying in triglyceride fatty acid saturation (P/S = 4.6 or 0.2), triglyceride load (66 or 165 mumoles/h) and cholesterol load (0 and 3.5 mumoles/h at the low oil infusion rate, and 0 and 11 mumoles/h at the high infusion rate). Triglyceride absorption averaged 95% for rats receiving the low and high infusion rates of the polyunsaturated oil (groups defined as 10P and 25P, respectively), and 77% for those receiving the saturated oil (10S and 25S). Estimated average relative lymph lipoprotein size was significantly larger during infusion of the high vs. low triglyceride load, and of the P vs. S oil (25P greater than 25S greater than 10P greater than 10S). Lymph cholesterol flux during infusion of oil only averaged 3.2 mumoles/h for all groups and was not significantly influenced by dietary fat saturation or triglyceride load. The initial rapid rise in lymph cholesterol after addition of cholesterol (mass + tracer) to the oils was due primarily to endogenous cholesterol. Thus, absorption of dietary cholesterol resulted in an initial displacement of endogenous cholesterol into the lymph. However, in samples collected 18--24 h after addition of cholesterol to the oil, 87--107% of the increased lymph cholesterol flux was exogenous (labeled). This increased flux was not significantly influenced by fat saturation of the infused oil and averaged 5.6 mumoles/h for rats in the low oil/lower cholesterol infusion groups, and 9.5 mumoles/h for those in the higher infusion groups. The percent esterified cholesterol in lymph of rats in the low oil infusion groups was significantly higher in the S vs. P animals during both infusion of oil only and of oil + cholesterol. The observed effects of fat saturation on lymph triglyceride flux, cholesterol esterification and lipoprotein size may have important consequences for subsequent metabolism of absorptive lipoproteins, and for their ultimate effects on plasma lipid levels.
在非禁食且胸导管插管的大鼠中研究脂质吸收情况，这些大鼠接受十二指肠内持续输注不同甘油三酯脂肪酸饱和度（P/S = 4.6或0.2）、甘油三酯负荷（66或165微摩尔/小时）以及胆固醇负荷（低油输注速率时为0和3.5微摩尔/小时，高输注速率时为0和11微摩尔/小时）的油。接受低输注速率和高输注速率多不饱和油的大鼠（分别定义为10P组和25P组）甘油三酯平均吸收率为95%，接受饱和油的大鼠（10S组和25S组）为77%。在输注高甘油三酯负荷与低甘油三酯负荷以及P油与S油期间，估计的平均相对淋巴脂蛋白大小显著更大（25P大于25S大于10P大于10S）。仅输注油期间，所有组的淋巴胆固醇通量平均为3.2微摩尔/小时，且不受膳食脂肪饱和度或甘油三酯负荷的显著影响。向油中添加胆固醇（质量 + 示踪剂）后，淋巴胆固醇最初的快速上升主要归因于内源性胆固醇。因此，膳食胆固醇的吸收导致内源性胆固醇最初向淋巴中转移。然而，在向油中添加胆固醇后18 - 24小时收集的样本中，淋巴胆固醇通量增加量的87 - 107%是外源性的（标记的）。这种增加的通量不受输注油的脂肪饱和度显著影响，低油/低胆固醇输注组大鼠平均为5.6微摩尔/小时，高输注组大鼠为9.5微摩尔/小时。在仅输注油以及输注油 + 胆固醇期间，低油输注组大鼠淋巴中胆固醇酯化百分比在S组动物中显著高于P组动物。观察到的脂肪饱和度对淋巴甘油三酯通量、胆固醇酯化和脂蛋白大小的影响可能对吸收性脂蛋白的后续代谢及其对血浆脂质水平的最终影响具有重要意义。
