Amino acids suppress intracellular protein degradation in rat liver during parenteral nutrition.
Amino acids suppress intracellular protein degradation in rat liver during parenteral nutrition.
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氨基酸在肠外营养期间抑制大鼠肝脏中的细胞内蛋白质降解。
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
Y. Natori
中科院分区：
文献类型：
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作者：
K. Chiku;H. Mochida;M. Yamamoto;Y. Natori
研究了氨基酸供应变化对肝脏蛋白质合成和降解速率以及血浆蛋白质合成和分泌速率的影响。大鼠通过输注含有四种不同水平（0、1.65、3.3和6.6%）氨基酸的总肠外营养液喂养7 d。通过注射大剂量的[3H]苯丙氨酸来测定肝脏中总蛋白合成的分数率。通过注射示踪剂剂量的[14C]亮氨酸，测量分泌完成后留在肝脏和存在于血浆中的蛋白质放射性，估计肝脏保留和输出新合成蛋白质的比例。0和1.65%氨基酸组血浆白蛋白合成率显著低于其他各组。然而，除了0%氨基酸组略高于其他各组外，饲喂不同氨基酸水平的大鼠肝脏生活蛋白的分数合成率基本相同。肝脏国产蛋白的分级降解率（以肝脏国产蛋白分级合成率与肝脏蛋白净增重之差计算）与输注液中氨基酸含量呈负相关（r = -0.999, P < 0.05），最高可达3.3%。由此可见，蛋白质降解在肝脏蛋白质质量的调节中起主导作用。
The effects of variations in the amino acid supply on the rates of synthesis and degradation of liver proteins and on the rate of synthesis and secretion of plasma proteins were investigated. Rats were nourished by infusion of total parenteral nutrition solutions containing four different levels (0, 1.65, 3.3 and 6.6%) of amino acids for 7 d. The fractional rate of total protein synthesis in the liver was determined by injecting a flooding dose of [3H]phenylalanine. The proportion of newly synthesized proteins retained and exported by the liver was estimated by injecting a tracer dose of [14C]leucine and then measuring the protein radioactivity remaining in the liver and present in the plasma after secretion was completed. The rate of plasma albumin synthesis was significantly lower in the 0 and 1.65% amino acid groups than in the other groups. The fractional synthesis rates of liver domestic proteins, however, were essentially the same in rats administered all levels of amino acids except for the 0% amino acid group, which showed a slightly higher value than the other groups. The fractional degradation rates of liver domestic proteins, calculated as the difference between the fractional synthesis rate of liver domestic proteins and the net gain of liver proteins, were found to be inversely related (r = -0.999, P < 0.05) to the level of amino acids in infusion solutions up to 3.3% amino acids. It was concluded that protein degradation plays the predominant role in the regulation of liver protein mass.