Kapadia C R, Colpoys M F, Jiang Z M, Johnson D J, Smith R J, Wilmore D W
JPEN J Parenter Enteral Nutr. 1985 Sep-Oct;9(5):583-9. doi: 10.1177/0148607185009005583.
Skeletal muscle glutamine (GLN) concentration falls following injury and infection. In an attempt to prevent this decline and to characterize its influence on the efflux of amino acid (AA) from skeletal muscle, we administered varying quantities of AA (0,2, and 4 g/kg X day) as saline or AA solutions with or without GLN enrichment to 22 postoperative dogs. Plasma and muscle AA were determined before and 24 hr after standard laparotomy. Hindquarter AA efflux was measured at 6 and 24 hr. Skeletal muscle nitrogen declined in saline controls (69.8 +/- 8.5 vs 52.8 +/- 8.4 mmol/liter; p less than 0.01), largely due to the fall in intracellular GLN (21.48 +/- 3.21 vs 15.86 +/- 3.80; p less than 0.05). Similar alterations were seen in the animals receiving 2 g/kg. However, both intracellular nitrogen and GLN were maintained in animals receiving 4 g/kg, whether the AA solutions contained GLN or not (skeletal muscle nitrogen before 64.3 +/- 8.6 mmol/l vs 65.4 +/- 7.0 after, GLN 19.2 +/- 3.4 vs 19.9 +/- 3.0). Hindquarter AA efflux was reduced in those animals at 6 hr compared with saline-treated animals (-6.52 +/- 1.8 and -7.70 +/- 5.90 vs -19.05 +/- 4.06 mumol/kg X min; p less than 0.05). Intracellular GLN can be maintained during operative stress with adequate nitrogen infusion. Replacing 50% of the balanced AA solution with GLN resulted in equally effective maintenance of intracellular GLN levels and a comparable reduction in skeletal muscle AA efflux. Preservation of normal intracellular GLN levels with adequate AA nutrition may be essential for the conservation of muscle protein.
损伤和感染后骨骼肌谷氨酰胺（GLN）浓度会下降。为了防止这种下降并确定其对骨骼肌氨基酸（AA）流出的影响，我们给22只术后犬静脉输注不同剂量的氨基酸（0、2和4 g/kg×天），以生理盐水或含或不含GLN强化的氨基酸溶液的形式给药。在标准剖腹手术前和术后24小时测定血浆和肌肉中的氨基酸水平。在术后6小时和24小时测量后肢氨基酸流出量。生理盐水对照组的骨骼肌氮含量下降（69.8±8.5对52.8±8.4 mmol/升；p<0.01），这主要是由于细胞内GLN含量下降（21.48±3.21对15.86±3.80；p<0.05）。接受2 g/kg剂量的动物也出现了类似的变化。然而，无论氨基酸溶液中是否含有GLN，接受4 g/kg剂量的动物其细胞内氮和GLN含量均得以维持（骨骼肌氮术前为64.3±8.6 mmol/升，术后为65.4±7.0，GLN术前为19.2±3.4，术后为19.9±3.0）。与生理盐水处理的动物相比，这些接受4 g/kg剂量的动物在术后6小时后肢氨基酸流出量减少（-6.52±1.8和-7.70±5.90对-19.05±4.06 μmol/kg×分钟；p<0.05）。在手术应激期间，通过充足的氮输注可维持细胞内GLN水平。用GLN替代50%的平衡氨基酸溶液可同样有效地维持细胞内GLN水平，并使骨骼肌氨基酸流出量得到类似程度的减少。通过充足的氨基酸营养维持正常的细胞内GLN水平对于肌肉蛋白的保存可能至关重要。
