Bouteloup-Demange C, Boirie Y, Déchelotte P, Gachon P, Beaufrère B
Laboratoire de Nutrition Humaine, Université d'Auvergne, Centre de Recherche en Nutrition Humaine, Clermont-Ferrand, France.
Am J Physiol. 1998 Mar;274(3):E541-6. doi: 10.1152/ajpendo.1998.274.3.E541.
Fractional protein synthesis rate (FSR) of duodenal mucosa was measured in two groups of six healthy young men, either in the fed state at the end of a 10-day standardized diet or after a 36-h fast. Protein synthesis rate was measured during a 9-h intravenous infusion of [13C]leucine and [2H5]phenylalanine. The fed group also received an intragastric tracer, [2H3]leucine, mixed with the liquid diet. At the end of the tracer infusion, an endoscopy was performed to take duodenal mucosal biopsies. The major results were that 1) duodenal mucosal protein synthesis was high, 48.0 +/- 8.5% (SE)/day by use of intravenous leucine tracer and intracellular leucine enrichment; 2) it was not affected by feeding whatever the tracer or the precursor pool used for the calculations; 3) the two intravenous tracers gave different FSR values; and 4) with the intragastric tracer, FSR was 25-220% of the rate calculated with the intravenous tracer, depending on the precursor pool used for the calculation. Thus absolute values of FSR should be taken with caution, because they depend on the precursor pool chosen, the route of tracer administration, and the tracer itself. However, gut mucosal protein synthesis as assessed by an intravenous tracer is not affected by feeding in humans.
在两组各六名健康年轻男性中测量十二指肠黏膜的蛋白质合成率（FSR），一组是在10天标准化饮食结束时的进食状态下，另一组是在禁食36小时后。在静脉输注[13C]亮氨酸和[2H5]苯丙氨酸9小时期间测量蛋白质合成率。进食组还接受了与流质饮食混合的胃内示踪剂[2H3]亮氨酸。在示踪剂输注结束时，进行内镜检查以获取十二指肠黏膜活检样本。主要结果如下：1）十二指肠黏膜蛋白质合成较高，通过静脉亮氨酸示踪剂和细胞内亮氨酸富集计算得出为48.0±8.5%（标准误）/天；2）无论用于计算的示踪剂或前体池如何，其均不受进食的影响；3）两种静脉示踪剂给出不同的FSR值；4）使用胃内示踪剂时，FSR是根据静脉示踪剂计算得出速率的25% - 220%，具体取决于用于计算的前体池。因此，应谨慎对待FSR的绝对值，因为它们取决于所选择的前体池、示踪剂给药途径以及示踪剂本身。然而，在人类中，通过静脉示踪剂评估的肠道黏膜蛋白质合成不受进食的影响。
