Hirschberg Y, Pomposelli J J, Mascioli E A, Bistrian B R, Blackburn G L
New England Deaconess Hospital, Laboratory of Nutrition/Infection, Boston, MA 02215.
JPEN J Parenter Enteral Nutr. 1990 Sep-Oct;14(5):463-6. doi: 10.1177/0148607190014005463.
Since the addition of lipid to intravenous feeding formulas, animal and human studies have shown impairment of the reticuloendothelial system (RES) due to slow rates of clearance and gradual accumulation of long chain triglycerides (LCT) in the liver. Medium chain triglycerides (MCT) accumulate only minimally in the liver and do not impair the RES. However, results from animal studies using technetium sulfur colloid (TSC) to assess RES function have been inconclusive. The present study reevaluates RES function after lipid infusion in guinea pigs as measured by organ distribution of TSC. Guinea pigs were fed 300 kcal/kg/day of total parenteral nutrition (TPN) for 2.5 days, with 50% of nonprotein calories as fat in the form of LCT or MCT, then injected intravenously with 2.5 or 25 microCi of TSC, and uptake by liver, spleen, and lungs was determined. Liver, lungs, and spleen all increased in size after TPN with LCT or MCT. Liver TSC uptake was significantly affected by the dose of TSC (p less than 0.05), with the high dose probably inducing an increased capacity of the liver to clear TSC from the blood. Liver uptake was not influenced by diet, but feeding MCT did significantly stimulate lung uptake of TSC (p less than 0.0001). This suggests that the hepatic TSC uptake system is not saturable, and may not be an appropriate measure of Kupffer cell function since the colloid is not phagocytosed. However, TSC blood clearance remains an excellent prognostic indicator for bacteremia and mortality in humans, and is useful for measuring global RES function.
自从在静脉营养配方中添加脂质以来，动物和人体研究表明，由于长链甘油三酯（LCT）在肝脏中的清除率缓慢和逐渐积累，网状内皮系统（RES）受到损害。中链甘油三酯（MCT）在肝脏中仅微量积累，不会损害RES。然而，使用锝硫胶体（TSC）评估RES功能的动物研究结果尚无定论。本研究通过TSC的器官分布重新评估豚鼠脂质输注后的RES功能。给豚鼠连续2.5天喂食300 kcal/kg/天的全胃肠外营养（TPN），其中50%的非蛋白热量以LCT或MCT形式的脂肪提供，然后静脉注射2.5或25微居里的TSC，并测定肝脏、脾脏和肺的摄取量。接受LCT或MCT的TPN后，肝脏、肺和脾脏的大小均增加。肝脏TSC摄取受TSC剂量的显著影响（p小于0.05），高剂量可能导致肝脏从血液中清除TSC的能力增强。肝脏摄取不受饮食影响，但喂食MCT确实显著刺激了肺对TSC的摄取（p小于0.0001）。这表明肝脏TSC摄取系统不饱和，并且由于胶体未被吞噬，可能不是评估库普弗细胞功能的合适指标。然而，TSC血液清除率仍然是人类菌血症和死亡率的优秀预后指标，并且可用于测量整体RES功能。
