Effect of starvation on intestinal amino acid absorption.
Effect of starvation on intestinal amino acid absorption.
复制标题
饥饿对肠道氨基酸吸收的影响。
DOI：
10.1152/ajplegacy.1969.217.3.747
复制
发表时间：
1969
期刊：
影响因子：
--
通讯作者：
S. Gray
中科院分区：
文献类型：
--
作者：
M. Steiner;S. Gray
斯坦纳、曼弗雷德和西摩尔·格雷。饥饿对肠道氨基酸吸收的影响。Am. J. Physiol.217（3）：747-752。1969.-采用在体技术研究了饥饿4天大鼠小肠对L-缬氨酸的吸收，并与正常非饥饿动物进行了比较。吸收介质含有L-缬氨酸作为唯一的氨基酸，10种必需氨基酸的等摩尔混合物，或酪蛋白水解产物。当吸收介质含有酪蛋白水解物（相对于L-缬氨酸为2 μ）时，饥饿和非饥饿动物之间每单位重量的小肠粘膜吸收没有显着差异。然而，当肠腔中含有10 mM L-缬氨酸溶液或必需氨基酸的混合物（各5 μ）时，饥饿大鼠表现出更大的L-缬氨酸转运速率和总量。在吸收过程中，肠粘膜组织保留了大量氨基酸，总量与吸收时间呈负相关。随着吸收时间的延长，游离氨基酸的含量逐渐减少，而蛋白质结合的L-缬氨酸的含量逐渐增加。与正常非饥饿动物相比，饥饿动物的粘膜组织中蛋白质的从头合成大大减少，两者都吸收酪蛋白水解产物。蛋白质合成饥饿引起细胞增殖、组织组成和代谢途径（4，9，13，19，26）中激素和酶活性（5，8，18，20，25）的广泛变化。不同的器官受到不同程度的影响。虽然大脑和心脏的重量几乎没有减轻，但骨骼肌失去了一些物质，肝脏和肠道的质量大大减少（1）。在小肠，特别是其上皮层，可以看到组织学结构、化学成分和生化功能的深刻变化（11，16，23，24）。这种变化可能会影响肠道的吸收能力。Levin等人研究了饥饿期间的氨基酸转运。(14)据我们所知，他们是唯一一个报道全面饥饿影响的作者。然而，由于他们只测试了单一氨基酸的吸收，并以远远超过肠腔内正常水平的浓度利用它们，他们的研究忽略了某些生理因素。
STEINER, MANFRED, AND SEYMOUR J. GRAY. Effect of starvation on intestinal amino acid absorption. Am. J. Physiol. 217 (3): 747-752. 1969.-The absorption of L-valine by small intestine was studied by an in vivo technique in 4-day starved rats and compared to that of normal nonstarved animals. The absorption medium contained either L-valine as the only amino acid, an equimolar mixture of the 10 essential amino acids, or a casein hydrolysate. Absorption per unit weight of small intestinal mucosa showed no significant difference between starved and nonstarved animals when the absorption medium contained casein hydrolysate (2 mu with respect to L-valine). When the intestinal lumen, however, contained a 10 mM L-valine solution or a mixture of essential amino acids (5 mu each), starved rats exhibited much greater rates and total magnitudes of L-valine transport. Amino acids were retained in significant quantities by the tissue of the intestinal mucosa during the absorption process, the total amount being inversely related to the absorption time. The fraction of free amino acids decreased and that of protein-incorporated L-valine increased with the time of absorption. De novo synthesis of protein in mucosal tissue was greatly reduced in starved as compared to normal nonstarved animals, both absorbing casein hydrolysate. protein synthesisSTARVATION PRODUCES extensive changes in hormonal and enzymatic activities(5, 8, 18, 20, 25) in cell proliferation, tissue composition, and metabolic pathways(4, 9, 13, 19, 26). Different organs are affected to different degrees. Whereas brain and heart have been shown to lose little weight, skeletal muscle loses some substance and liver and intestinal tract are extensively reduced in mass (1). Profound alterations of histologic structure, chemical composition, and biochemical function can be seen in the small intestine, particularly in its epithelial layer (11, 16, 23, 24). Such changes can be expected to influence the absorptive capability of the intestine. Amino acid transport during starvation has been studied by Levin et al.(14) who, to our knowledge, were the only authors reporting on the effect of total starvation. Insofar as they tested only the absorption of single amino acids and utilized them at concentrations far exceeding the normal level within the intestinal lumen, their studies left certain physiologic considerations unattended.