Schiffelers S L, Saris W H, van Baak M A
Nutrition Toxicology and Environment Research Institute Maastricht, Department of Human Biology, Maastricht University, Maastricht, The Netherlands.
Int J Obes Relat Metab Disord. 2001 Jan;25(1):33-8. doi: 10.1038/sj.ijo.0801528.
To examine whether a certain increase in plasma free fatty acid (FFA) concentration leads to similar increases in lipid oxidation and energy expenditure in obese and lean men.
The study protocol consisted of a 30 min baseline period after which subjects received an i.v. bolus of 1000 IE heparin. Then consecutive infusions of 4.9, 9.8 and 19.6 microl/kg fat-free mass (FFM).min of a lipid heparin mixture were started, each infusion for 30 min.
Eleven obese and 13 lean men with a mean body mass index (BMI) of 34.2+/-1.0 (+/-s.e.m.) and 23.9+/-0.5 kg/m(2) and age 46.0+/-1.0 and 42.6+/-1.5 y, respectively.
Energy expenditure, respiratory exchange ratio (RER) and carbohydrate and lipid oxidation were continuously measured by indirect calorimetry. At the end of each infusion period, a blood sample was taken for FFA, glycerol, insulin, beta-hydroxybutyrate, noradrenaline and adrenaline determination.
At baseline, plasma FFA levels were comparable in both groups. Lipid heparin infusion increased plasma FFA concentration by 301+/-47 micromol/l and 332+/-27 micromol/l in obese and lean men. Energy expenditure increased similarly in obese and lean men (0.34+/-0.08 vs 0.40+/-0.08 kJ/min, NS) during lipid heparin infusion, whereas RER decreased similarly in both groups. Lipid oxidation rates were comparable at baseline and increased similarly in obese and lean men (19+/-5 vs 13+/-4 mg/min, NS). Baseline plasma insulin levels were higher in the obese, but did not change during lipid heparin infusion. Plasma beta-hydroxybutyrate concentrations were similar at baseline, but increased significantly less in the obese during lipid heparin infusion. Baseline noradrenaline and adrenaline concentrations did not differ significantly between groups. During lipid heparin infusion, plasma noradrenaline levels decreased significantly, but plasma adrenaline levels remained unchanged in both groups.
A certain increase in plasma FFA concentration leads to similar increases in lipid oxidation and energy expenditure in obese and lean men. The accumulation of fat in obese subjects may therefore be more likely to be due to a defect in adipose tissue lipolysis than a defect in lipid oxidation. International Journal of Obesity (2001) 25, 33-38
研究血浆游离脂肪酸（FFA）浓度一定程度的升高是否会使肥胖男性和瘦男性的脂质氧化及能量消耗产生相似程度的增加。
研究方案包括30分钟的基线期，之后受试者静脉注射1000国际单位肝素。然后开始以4.9、9.8和19.6微升/千克去脂体重（FFM）·分钟的剂量连续输注脂质肝素混合物，每次输注30分钟。
11名肥胖男性和13名瘦男性，平均体重指数（BMI）分别为34.2±1.0（±标准误）和23.9±0.5千克/平方米，年龄分别为46.0±1.0岁和42.6±1.5岁。
通过间接量热法持续测量能量消耗、呼吸交换率（RER）以及碳水化合物和脂质氧化。在每个输注期结束时，采集血样测定FFA、甘油、胰岛素、β-羟基丁酸、去甲肾上腺素和肾上腺素。
在基线时，两组的血浆FFA水平相当。脂质肝素输注使肥胖男性和瘦男性的血浆FFA浓度分别升高301±47微摩尔/升和332±27微摩尔/升。在脂质肝素输注期间，肥胖男性和瘦男性的能量消耗增加程度相似（分别为0.34±0.08与0.40±0.08千焦/分钟，无显著差异），而两组的RER下降程度相似。基线时脂质氧化率相当，肥胖男性和瘦男性的脂质氧化率升高程度相似（分别为19±5与13±4毫克/分钟，无显著差异）。肥胖者的基线血浆胰岛素水平较高，但在脂质肝素输注期间未发生变化。基线时血浆β-羟基丁酸浓度相似，但在脂质肝素输注期间肥胖者的升高幅度明显较小。两组之间基线时去甲肾上腺素和肾上腺素浓度无显著差异。在脂质肝素输注期间，血浆去甲肾上腺素水平显著下降，但两组的血浆肾上腺素水平均保持不变。
血浆FFA浓度一定程度的升高会使肥胖男性和瘦男性的脂质氧化及能量消耗产生相似程度的增加。因此，肥胖受试者体内脂肪的积累更可能是由于脂肪组织脂解缺陷而非脂质氧化缺陷所致。《国际肥胖杂志》（2001年）25卷，33 - 38页
