肠外营养中脂肪乳剂对红细胞膜磷脂脂肪酸组成的影响

Effect of lipid emulsions on composition of phospbolipid fatty acids in red blood vcell membrane in rats on total parenteral nutrition

利用大鼠胃肠外营养(PN)模型观察长链脂肪乳剂(LCT),中链/长链脂肪乳剂(MCT/LCT),以及不含脂肪乳剂对红细胞(RBC)膜磷脂肪酸组成的影响。PN总热量为300kcal.kg^(-1).d^(-1),非蛋白热卡:氮为182:1,LCT组,MCT/LCT组分别由10％的Intralipid和10％的Lypofundin提供30％的非蛋白热卡。7天后,分析RBC膜磷脂酰二极管胆硷(PC)脂肪酸组成。结果发现,不含脂肪乳剂组18:1n-9明显高于对照组;LCT组18:2n-6升高,而20:4n-6却下降;MCT/LCT组与对照组相比,脂肪酸组成变化不明显。结论:无脂肪乳剂TPN导致必需脂肪酸缺乏;LCT组由于18:2n-6的过量供给,抑制Δ6去饱和酶的活性,MCT/LCT组由于50％LCT被MCT替代,减低了对此酶活性抑制。

Fatty acid composition of phospholipids in red blood cell membrane was studied in rats after 7 days of total parenteral nutrition which contained fat-free of LCT or MCT/LCT TPN providing 300kcal·kg-1·d-1 of total energy with a nonprotein calorie/nitrogen ratio of 182:1. 30 % nonprotein calories were provied by 10% Intralipid in LCT group and by 10% Intralipid in MCT/LCT group, After 7 days of TPN , the changes in phospholipid fatty acid components were most pronounced in phos-phatidylcholine(PC) . 18: 1n-9 in fat-free group was higher than other groups. An increase of 18:2n-6 and a significant decrease of 20: 4n-6 in LCT group were noted and there was no significant differences in fatty acid compositions in MCT/LCT group (50% of the soybean oil in the LCT emulsion being replaced with medium-chain triglycerides) in comparison to the control group. These results suggested that the TPN containing no lipid emulsions would induce essential fattyacid deficiency (EFAD) easily, Inhibition of △-6 de-saturase activity could be induced by EFA excess in LCT emulsion and such an enzyme inhibition could be prevented with MCT/LCT emulsion which contains less EFA.