Millar J S, Lichtenstein A H, Cuchel M, Dolnikowski G G, Hachey D L, Cohn J S, Schaefer E J
Lipid Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA.
J Lipid Res. 1995 Jun;36(6):1155-67.
Levels of plasma very low density lipoprotein (VLDL) and low density lipoprotein (LDL) constituents increase with age. In an attempt to further define the mechanisms responsible for these changes, kinetic studies of VLDL and LDL apolipoprotein (apo) B-100 were carried out in 19 normolipidemic male subjects with plasma total cholesterol and triglyceride levels below the 90th percentile whose ages ranged from 24 to 73 years. Subjects were maintained on standardized diets consisting of 47-49% of calories as carbohydrate, 15% protein, and 36-40% fat (15-17% saturated, 15-17% monounsaturated, 6% polyunsaturated) with 150 mg cholesterol/1000 kcal. At the end of the diet period, the metabolism of apoB-100 within VLDL, intermediate density lipoprotein (IDL), and LDL was studied in the fed state using a primed-constant infusion of [2H3]leucine. Data were fit to a multicompartmental model to determine residence times and production rates of apoB-100 in each fraction. There were significant positive correlations between age and VLDL, IDL, and LDL apoB-100 concentrations (r = 0.50, 0.62, and 0.69; P = 0.03, 0.004, and 0.001, respectively). There was a positive correlation between age and the production rate of VLDL apoB-100 (r = 0.50, P = 0.03), but there was no significant relationship between age and either IDL or LDL apoB-100 production rates. Age was also positively correlated with the residence time of LDL apoB-100 (r = 0.68 P = 0.001). Our data suggest that the age-associated increase in VLDL apoB-100 is due to an increased production rate of this constituent, whereas the age-associated increase in LDL apoB-100 is due to an increased residence time of these particles in plasma.
血浆极低密度脂蛋白（VLDL）和低密度脂蛋白（LDL）成分的水平随年龄增长而升高。为了进一步明确导致这些变化的机制，对19名血脂正常的男性受试者进行了VLDL和LDL载脂蛋白（apo）B - 100的动力学研究，这些受试者的血浆总胆固醇和甘油三酯水平低于第90百分位数，年龄在24岁至73岁之间。受试者维持标准化饮食，碳水化合物提供47 - 49%的热量，蛋白质提供15%的热量，脂肪提供36 - 40%的热量（15 - 17%为饱和脂肪，15 - 17%为单不饱和脂肪，6%为多不饱和脂肪），每1000千卡含150毫克胆固醇。在饮食期结束时，在进食状态下使用[2H3]亮氨酸的预充 - 恒速输注研究了VLDL、中间密度脂蛋白（IDL）和LDL中apoB - 100的代谢。数据拟合多室模型以确定每个组分中apoB - 100的停留时间和生成速率。年龄与VLDL、IDL和LDL apoB - 100浓度之间存在显著正相关（r分别为 = 0.50、0.62和0.69；P分别为 = 0.03、0.004和0.001）。年龄与VLDL apoB - 100的生成速率之间存在正相关（r = 0.50，P = 0.03），但年龄与IDL或LDL apoB - 100生成速率之间无显著关系。年龄与LDL apoB - 100的停留时间也呈正相关（r = 0.68，P = 0.001）。我们的数据表明，与年龄相关的VLDL apoB - 100升高是由于该成分生成速率增加，而与年龄相关的LDL apoB - 100升高是由于这些颗粒在血浆中的停留时间增加。
