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Studies on alterations of free aromatic amino acids and protein turnover in skeletal muscles under surgical stresses.

手术应激下骨骼肌中游离芳香氨基酸和蛋白质周转变化的研究。

基本信息

批准号：
63570614
负责人：
MORI Eigo
金额：
$ 1.34万
依托单位：
Teikyo University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63570614/
关键词：
Metabolism of Aromatic Amino Acids Free Aromatic Amino Acids Scalded Rats Septic Rats 芳香族アミノ酸の代謝

项目摘要

We examined the relationship between the elevation of blood phenylalanine concentrations often observed In trauma or infected patients without hepatic dysfunction and alterations of liver phenylalanine catabolism in rats undergoing pathophysiologically different stresses, either sepsis or scald injury. The adenine nucleotide levels and the energy state in tissues of abodominal and femoral muscles and diaphragm were maintained by breakdown of phosphocreatine, but protein degradation was promoted in these tissues. The alterations of many amino acid levels in abdominal and femoral muscles paralleled those of the corresponding amino acid levels in plasma under these stresses. The observed changes in free amino acids in plasma and the muscles well reflected the enhanced protein degradation in skeletal muscles. Phenylalanine hydroxylase activity, as measured using a naturally occurring cofactor, decreased by 40%, while phenylalanine-pyruvate aminotransferase was activated by 25% in the livers of the septic rats as compared with those of the controls. Such activation, caused by an increase in glucagon levels, resulted in a 76% increase in oxidation of phenylalanine over that of controls, as measured by pulse-administration of ^<14>C-labeled phenylalanine. In the scalded rats whose plasma phenylalanine level showed a comparable but temporary rise, no significant alterations in these enzyme activities and phenylalanine oxidation occurred. These results indicate that reduction of phenylalanine hydroxylation was also responsible for the elevation of the plasma phenylalanine level in infected rats during massive mobilization of amino acids from skeletal muscles under conditions of enhanced and sustaining catabolism.

我们研究了在创伤或无肝功能障碍的感染患者中经常观察到的血液苯丙氨酸浓度升高与经历不同病理生理应激（败血症或烫伤损伤）的大鼠肝脏苯丙氨酸分解代谢的改变之间的关系。磷酸肌酸的分解维持了腹肌、股肌和膈肌组织中的腺嘌呤核苷酸水平和能量状态，但促进了这些组织中蛋白质的降解。在这些压力下，腹肌和股肌中许多氨基酸水平的变化与血浆中相应的氨基酸水平相似。血浆和肌肉中游离氨基酸的变化很好地反映了骨骼肌中蛋白质降解的增强。苯丙氨酸羟化酶活性，用自然产生的辅助因子测量，下降了40%，而苯丙氨酸-丙酮酸转氨酶在脓毒症大鼠的肝脏中，与对照组相比，被激活了25%。这种由胰高血糖素水平升高引起的激活，导致苯丙氨酸的氧化比对照组增加76%，这是通过脉冲给药^<14> c标记的苯丙氨酸来测量的。在被烫伤的大鼠中，血浆苯丙氨酸水平显示出类似但短暂的上升，这些酶活性和苯丙氨酸氧化没有发生显著变化。这些结果表明，在分解代谢增强和持续的情况下，在骨骼肌大量动员氨基酸时，苯丙氨酸羟基化的减少也是感染大鼠血浆苯丙氨酸水平升高的原因。