Intestinal glutamate metabolism
Intestinal glutamate metabolism
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DOI：
10.1093/jn/130.4.978s
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发表时间：
2000-04-01
影响因子：
4.2
通讯作者：
Jahoor, F
中科院分区：
文献类型：
--
作者：
Reeds, PJ;Burrin, DG;Jahoor, F
虽然众所周知肠道具有高代谢率，但用于产生必要能量的底物仍然很难建立，特别是在喂养的动物中。在进食条件下，肠道使用的底物的定量由于潜在的氧化前体由饮食和动脉循环提供而变得复杂。为了避免这个问题，并解决用于在肠道中产生ATP的化合物的问题，我们将门静脉营养平衡的测量与[U-C-13]底物的肠内和静脉内输注相结合。我们研究了快速生长的仔猪，这些仔猪食用基于全脂牛奶蛋白的饮食。结果表明，95%的膳食谷氨酸提交给粘膜代谢的第一关，这50%代谢为CO2。饮食中葡萄糖被氧化到非常有限的程度，动脉谷氨酰胺提供不超过15%的CO2生产的门静脉引流内脏。谷氨酸是肠道能量产生的最大贡献者。结果还表明，饲料谷氨酸似乎是一个特定的前体谷胱甘肽，精氨酸和脯氨酸的生物合成的小肠粘膜。这些研究表明，饮食中的谷氨酸盐在肠道中具有重要的功能作用。此外，这些功能显然不同于动脉谷氨酰胺，底物已收到最多的关注。
Although it is well known that the intestinal tract has a high metabolic rate, the substrates that are used to generate the necessary energy remain poorly established, especially in fed animals. Under fed conditions, the quantification of substrate used by the gut is complicated by the fact that potential oxidative precursors are supplied from both the diet and the arterial circulation. To circumvent this problem, and to approach the question of the compounds used to generate ATP in the gut, we combined measurements of portal nutrient balance with enteral and intravenous infusions of [U-C-13]substrates. We studied rapidly growing piglets that were consuming diets based on whole-milk proteins. The results revealed that 95% of the dietary glutamate presented to the mucosa was metabolized in first pass and that of this, 50% was metabolized to CO2. Dietary glucose was oxidized to a very limited extent, and arterial glutamine supplied no >15% of the CO2 production by the portal-drained viscera. Glutamate was the single largest contributor to intestinal energy generation. The results also suggested that dietary glutamate appeared to be a specific precursor for the biosynthesis of glutathione, arginine and proline by the small intestinal mucosa. These studies imply that dietary glutamate has an important functional role in the gut. Furthermore, these functions are apparently different from those of arterial glutamine, the substrate that has received the most attention.