大强度游泳抑制小鼠骨骼肌谷氨酰胺合成酶活性

Inhibition of Glutamine Synthetase by High Intensity Swimming in Skeleton Muscle of Mice

分析不同强度运动负荷对血浆和骨骼肌谷氨酰胺水平变化与骨骼肌谷氨酰胺合成酶活性变化，探讨运动影响血浆谷氨酰胺水平变化的机制。ＢＡＬ／Ｃ小鼠不负重或２％负重不同强度游泳，每天２ ｈ，持续８周。与对照组比较，大强度游泳组动物血浆（０．４６±０． １０、０． １２±０．０２ ｍｍｏｌ／Ｌ，ｐ＜０．０１）和肌肉（４．９２±０． ９８、１． ０３±０． ３７ ｍｍｏｌ／Ｌ，ｐ＜０．０１）中的谷氨酰胺浓度降低，骨骼肌谷氨酰胺合成酶活性抑制（１８７４±１９１、１２４６±２２０ ｎｍｏｌ／ｍｉｎ／ｇ蛋白， ｐ＜０．０１）；而中等强大游泳升高血浆谷氨酰胺浓度（０．６４±０．０６ ｍｍｏｌ／Ｌ，ｐ＜０．０１）。小鼠在中等强反运动时，谷氨酰胺代谢表现了积极的代偿变化。但在大强度运动时，动物的体重增长减缓，血浆和肌肉谷氨酰胺水平均大幅度降低。结果提示，导致血浆谷氨酰胺水平降低的机制之一是骨骼肌中的谷氨酰胺合成酶抑制。

To analyze the effect of different intensity of exercise on glutamine levels in plasma and muscle and approach the mechanism of changes of plasma glutamine in exercise, BAL/C mice were randomly divided into middle intensity exercise (no extra load), high intensity exercise (2% bodyweight load) and control groups to swim for 2 hours/day and 8 weeks. Compared with the control group, high intensity exercise reduced glutamine levels in plasma (0. 46±0. 10, 0. 12 ± 0. 02 mmol/L, p＜0. 01) and muscle (4. 92± 0. 98 , 1. 03± 0. 37 mmol/L, p＜0. 01), and reduced the activity of glutamine synthetase in muscle (1874± 191, 1246 ± 220 mmol/min/mg, p＜0.01) ; middle. intensity exercise increased glutamine levels in plasma (0. 64±0. 06 mmol/L, p<0. 01). The results suggest that experimental animals showed a posi- tive compensation in glutamine metabolism after middle intensity exercise, while they failed to maintain a balance in glutamine metabolism after high intensity exercise. The reduction of glutamine in plasma and muscle and the slowed growth rate of body weight, observed in this group animals, may be partly attributed to inhibition of muscle glutamine synthetase.