Oliveira M R M, Maranhão R C
Faculty of Pharmaceutical Sciences, and Heart Institute of the Medical School Hospital (INCOR-HCFMUSP), University of São Paulo, Brazil.
Metabolism. 2002 Sep;51(9):1097-103. doi: 10.1053/meta.2002.34698.
Chylomicrons carry dietary fats in the bloodstream for storage in body tissues, and thus play an important role in obesity. The 2-step chylomicron metabolism consists of lipolysis by lipoprotein lipase (LPL) on vessel walls and hepatic uptake of triglyceride-depleted remnants. A triglyceride-rich emulsion that mimics chylomicrons, labeled with [9,10-(3)H]glycerol-trioleate (TG) and [1-(14)C] cholesteryl-oleate (CE) was intravenously injected into 14 obese women with body mass index between 30 and 40 kg/m(2) (age, 30 to 40 years), before and after a 2-month energy-restricted diet and into non-obese controls for determination of radioactive lipid plasma kinetics. TG kinetics evaluates lipolysis, whereas CE kinetics evaluates remnant removal. The emulsion TG fractional clearance rate (FCR, in min(-1)) was similar in obese women and their controls (0.126 +/- 0.065; controls, 0.111 +/- 0.031), but the CE-FCR was pronouncedly reduced in the obese subjects (0.028 +/- 0.014; controls, 0.070 +/- 0.009 min(-1); P <.0001). After the energy-restricted diet, TG-FCR was reduced in the obese women (0.075 +/- 0.044 min(-1); P <.05), but CE-FCR was unchanged (0.032 +/- 0.025 min(-1)). Therefore, the lipolysis of the chylomicron-like emulsion is normal in obese women, but remnant removal from the plasma is diminished. After active weight loss by an energy-restricted diet, the remnant removal was unchanged but lipolysis was diminished, possibly due to adaptative changes in LPL activity.
乳糜微粒将膳食脂肪携带至血液中以便储存于身体组织，因此在肥胖症中发挥重要作用。乳糜微粒的两步代谢过程包括血管壁上脂蛋白脂肪酶（LPL）的脂解作用以及肝脏对甘油三酯耗尽的残余物的摄取。将一种富含甘油三酯的乳剂静脉注射到14名体重指数在30至40kg/m²（年龄30至40岁）的肥胖女性体内，该乳剂模拟乳糜微粒，用[9,10-(³)H]甘油三油酸酯（TG）和[1-(¹⁴)C]胆固醇油酸酯（CE）进行标记，在2个月能量限制饮食前后以及注射到非肥胖对照组体内，用于测定放射性脂质的血浆动力学。TG动力学评估脂解作用，而CE动力学评估残余物清除情况。肥胖女性及其对照组的乳剂TG分数清除率（FCR，单位为min⁻¹）相似（0.126±0.065；对照组为0.111±0.031），但肥胖受试者的CE-FCR显著降低（0.028±0.014；对照组为0.070±0.009min⁻¹；P<0.0001）。能量限制饮食后，肥胖女性的TG-FCR降低（0.075±0.044min⁻¹；P<0.05），但CE-FCR未改变（0.032±0.025min⁻¹）。因此，肥胖女性中类似乳糜微粒的乳剂的脂解作用正常，但血浆中残余物的清除减少。通过能量限制饮食积极减重后，残余物清除未改变，但脂解作用减弱，这可能是由于LPL活性的适应性变化所致。
