Effects of glucocorticoids on glutamine metabolism in skeletal muscle.
Effects of glucocorticoids on glutamine metabolism in skeletal muscle.
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糖皮质激素对骨骼肌谷氨酰胺代谢的影响。
DOI：
10.1152/ajpendo.1984.247.1.e75
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Wilmore,DW
中科院分区：
文献类型：
--
作者：
Muhlbacher,F;Kapadia,CR;Colpoys,MF;Smith,RJ;Wilmore,DW
研究了地塞米松对犬氮和氨基酸代谢的影响，以深入了解糖皮质激素在分解代谢疾病中加速蛋白水解和改变谷氨酰胺代谢中的作用。在以0.44 mg X天-1 X kg-1的剂量给予地塞米松后，氮平衡从轻微正值（+0.126 g N X天-1 X kg-1）变为显著负值（-0.278 g N X天-1 X kg-1）。这与骨骼肌中总游离氨基酸氮下降23%有关，其中80%的下降由谷氨酰胺减少引起。血浆谷氨酰胺浓度下降了26%，虽然总血浆游离氨基酸氮是不变的，因为丙氨酸增加了49%。谷氨酰胺的细胞内和循环水平的改变并不伴随着骨骼肌中谷氨酰胺合成酶或谷氨酰胺酶活性的可测量的变化。后四分之一氨基酸通量测量表明，细胞内谷氨酰胺浓度的下降与骨骼肌谷氨酰胺流出量的显着增加。尽管细胞内/细胞外谷氨酰胺梯度变化极小，但仍发生了这种情况。它的结论是，加速肌肉谷氨酰胺释放糖皮质激素引起的是一个主要的贡献者在肌肉中发生的严重疾病期间谷氨酰胺水平下降。
The effects of dexamethasone on nitrogen and amino acid metabolism in the dog were studied in order to gain insight into the role of glucocorticoids in accelerated proteolysis and altered metabolism of glutamine in catabolic illnesses. After dexamethasone administration at a dose of 0.44 mg X day-1 X kg-1, nitrogen balance shifted from slightly positive (+0.126 g N X day-1 X kg-1) to markedly negative (-0.278 g N X day-1 X kg-1). This was associated with a 23% fall in total free amino acid nitrogen in skeletal muscle, with 80% of the decline accounted for by a decrease in glutamine. Plasma glutamine concentration decreased by 26%, although total plasma free amino acid nitrogen was unchanged because of a 49% increase in alanine. The alterations in intracellular and circulating levels of glutamine were not accompanied by measurable changes in glutamine synthetase or glutaminase activities in skeletal muscle. Hindquarter amino acid flux measurements demonstrated that the decline in intracellular glutamine concentration was associated with a marked increase in glutamine efflux from skeletal muscle. This occurred in spite of minimal changes in the intracellular/extracellular glutamine gradient. It is concluded that accelerated muscle glutamine release caused by glucocorticoids is a major contributor to the decreased glutamine levels in muscle that occur during critical illnesses.