Druml Wilfred, Fischer Margot
Division of Nephrology, IIIrd Medical Department, University of Vienna, Vienna, Austria.
Wien Klin Wochenschr. 2003 Nov 28;115(21-22):767-74. doi: 10.1007/BF03040501.
Lipid emulsions have become an indispensable component of parenteral nutrition. Commercially available emulsions mostly have an identical composition of triglycerides (from plant oils) and egg-yolk phospholipids as emulsifier. Previous attempts to improve the composition of lipid emulsions have focused mainly on the triglyceride moiety. In the first fundamental modification of a lipid emulsion since their broader introduction into clinical medicine, we included free cholesterol in a lipid emulsion. We evaluated elimination and hydrolysis of triglycerides and lipid oxidation (by indirect calorimetry) in 10 healthy male normolipemic volunteers, comparing a conventional lipid emulsion (20% triglycerides) with an otherwise identical emulsion with the addition of 4 g/l free cholesterol. The rise in plasma triglycerides was mitigated during infusion of the cholesterol-enriched solution (323.8 +/- 27.5 vs. 202.0 +/- 18.9 mg.dL-1, p < 0.001), plasma half-life was reduced (41.6 +/- 5.4 vs. 29.3 +/- 5.1 min, p < 0.05), and total-body clearance was enhanced (0.96 +/- 0.1 vs. 1.52 +/- 0.2 ml.b.w.(.)min-1, p < 0.02). The rise in plasma free fatty acids (400.7 +/- 39.0 vs. 532.2 +/- 64.0 mumol.L-1; p < 0.02) and ketone bodies (beta-hydroxybutyrate) (151.6 +/- 37.0 vs. 226.3 +/- 33.01 mumol.L-1; p < 0.02) was augmented. Increases in plasma insulin and glucagon were less pronounced (p < 0.05). The fall in respiratory quotient was greater and the fraction of lipid oxidation as a percentage of total energy expenditure was increased (66.2% +/- 6.0 vs. 70.9% +/- 6.3, p < 0.05) during infusion of the modified solution. No impairment of gas exchange or other side effects were observed. Taken together these results indicate that the elimination of a cholesterol-supplemented lipid emulsion is accelerated, triglyceride hydrolysis is enhanced, and lipid oxidation is augmented. Thus, addition of cholesterol to a lipid emulsion might not only present a means of providing cholesterol in parenteral nutrition but also help to reshape artificial lipid particles to a more chylomicron-resembling composition and improve lipid utilization.
脂质乳剂已成为肠外营养不可或缺的组成部分。市售乳剂大多具有相同的甘油三酯（来自植物油）组成以及作为乳化剂的蛋黄磷脂。以往改善脂质乳剂组成的尝试主要集中在甘油三酯部分。在脂质乳剂自广泛引入临床医学以来的首次根本性改良中，我们在脂质乳剂中加入了游离胆固醇。我们在10名健康的血脂正常男性志愿者中评估了甘油三酯的消除与水解以及脂质氧化（通过间接量热法），将一种传统脂质乳剂（20%甘油三酯）与另一种添加了4 g/l游离胆固醇的相同乳剂进行比较。在输注富含胆固醇的溶液期间，血浆甘油三酯的升高得到缓解（323.8±27.5 vs. 202.0±18.9 mg·dL⁻¹，p<0.001），血浆半衰期缩短（41.6±5.4 vs. 29.3±5.1分钟，p<0.05），全身清除率提高（0.96±0.1 vs. 1.52±0.2 ml·bw⁻¹·min⁻¹，p<0.02）。血浆游离脂肪酸（400.7±39.0 vs. 532.2±64.0 μmol·L⁻¹；p<0.02）和酮体（β-羟基丁酸）（151.6±37.0 vs. 226.3±33.01 μmol·L⁻¹；p<0.02）的升高更为明显。血浆胰岛素和胰高血糖素的升高不太显著（p<0.05）。在输注改良溶液期间，呼吸商的下降更大，脂质氧化占总能量消耗的百分比增加（66.2%±6.0 vs. 70.9%±6.3，p<0.05）。未观察到气体交换受损或其他副作用。综上所述，这些结果表明添加胆固醇的脂质乳剂的消除加快，甘油三酯水解增强，脂质氧化增加。因此，向脂质乳剂中添加胆固醇不仅可能是在肠外营养中提供胆固醇的一种方式，而且有助于将人工脂质颗粒重塑为更类似于乳糜微粒的组成并改善脂质利用。
