Abdel-Fattah G, Fernandez M L, McNamara D J
Department of Nutritional Sciences, University of Arizona, Tucson 85721, USA.
J Lipid Res. 1995 Jun;36(6):1188-98.
We investigated the effects of dietary fat saturation on very low density lipoprotein (VLDL) production in guinea pigs fed semipurified diets containing 15% (w/w) fat, either corn oil (CO, 58% linoleic acid), lard (LA, 42% oleic and 24% palmitic acids) or palm kernel oil (PK, 52% lauric and 18% myristic acids) for 4 weeks. Animals were given an intravenous injection of Triton WR 1339 to block VLDL catabolism and rates of VLDL triacylglycerol (TAG) and apolipoprotein (apo) B secretion were measured over time. Plasma TAG concentrations increased linearly for 8 h (r = 0.99) and VLDL-TAG secretion rates were significantly higher (P < 0.01) in guinea pigs fed LA (72.7 +/- 14.7 mg/kg-h, n = 12) compared to animals fed PK (55.4 +/- 13.4 mg/kg-h, n = 12) or CO (48.6 +/- 17.5 mg/kg-h, n = 15). VLDL apoB secretion rates were highest in PK-fed animals (3.1 +/- 1.8 mg/kg-h) compared to guinea pigs fed LA (1.5 +/- 0.8 mg/kg-h) or CO (1.1 +/- 0.6 mg/kg-h) diets (P < 0.005). Concurrent with analysis of VLDL secretion, turnover of 125I-labeled LDL was measured. Low density lipoprotein (LDL) fractional catabolic rates were not altered by Triton treatment and LDL apoB specific radioactivity (cpm/microgram) did not change over time indicating that: a) the Triton blockage of VLDL catabolism was complete, and b) there was no direct secretion of LDL by the liver. These data demonstrate that intake of lard increases the rate of VLDL-triacylglycerol secretion and that nascent VLDL particles from the lard and corn oil diet groups have the same relative triacylglycerol content, whereas palm kernel oil intake increases secretion of VLDL particles which have a reduced triacylglycerol content. These results demonstrate that dietary fat chain length and saturation have specific effects on VLDL secretion rates affecting both particle number and composition.
我们研究了膳食脂肪饱和度对豚鼠极低密度脂蛋白（VLDL）生成的影响。给豚鼠喂食含15%（w/w）脂肪的半纯化日粮4周，脂肪来源分别为玉米油（CO，含58%亚油酸）、猪油（LA，含42%油酸和24%棕榈酸）或棕榈仁油（PK，含52%月桂酸和18%肉豆蔻酸）。给动物静脉注射 Triton WR 1339以阻断VLDL分解代谢，并随时间测量VLDL三酰甘油（TAG）和载脂蛋白（apo）B的分泌速率。血浆TAG浓度在8小时内呈线性增加（r = 0.99），与喂食PK（55.4±13.4 mg/kg-h，n = 12）或CO（48.6±17.5 mg/kg-h，n = 15）的动物相比，喂食LA的豚鼠（72.7±14.7 mg/kg-h，n = 12）的VLDL-TAG分泌速率显著更高（P < 0.01）。与喂食LA（1.5±0.8 mg/kg-h）或CO（1.1±0.6 mg/kg-h）日粮的豚鼠相比，喂食PK的动物（3.1±1.8 mg/kg-h）的VLDL apoB分泌速率最高（P < 0.005）。在分析VLDL分泌的同时，测量了125I标记的LDL的周转率。Triton处理未改变低密度脂蛋白（LDL）的分数分解代谢率，且LDL apoB比放射性（cpm/μg）随时间未发生变化，这表明：a）Triton对VLDL分解代谢的阻断是完全的，b）肝脏没有直接分泌LDL。这些数据表明，摄入猪油会增加VLDL-三酰甘油的分泌速率，且来自猪油和玉米油日粮组的新生VLDL颗粒具有相同的相对三酰甘油含量，而摄入棕榈仁油会增加三酰甘油含量降低的VLDL颗粒的分泌。这些结果表明，膳食脂肪链长度和饱和度对VLDL分泌速率有特定影响，影响颗粒数量和组成。
