补充谷氨酰胺对运动小鼠谷氨酰胺代谢的影响

目的　探讨大强度慢性运动情况下 ,补充谷氨酰胺 (Gln)对血浆和骨骼肌 Gln水平、组织 Gln合成酶和谷氨酰胺酶活性变化的影响。方法　BAL/C小鼠负重 (2 %体重 )游泳 ,每天2 h,持续 8w。结果　与对照组比较 ,大强度游泳组动物血浆和肌肉中的 Gln浓度分别降低 74%(P<0 .0 1 )和 79%(P<0 .0 1 ) ,骨骼肌 Gln合成酶活性降低 3 3 .5 %(P<0 .0 1 ) ,淋巴细胞谷氨酰胺酶活性增加 3 1 5 %(P<0 .0 1 )。与游泳组比 ,游泳 +Gln补充组血浆和骨骼肌 Gln浓度分别提高了1 42 %(P<0 .0 1 )和 44.7%(P=0 .0 5 6 )、骨骼肌 Gln合成酶增加 1 8.0 %(P<0 .0 1 ) ,淋巴细胞谷氨酰胺酶降低了 2 5 .4%(P<0 .0 5 )。结论　大强度运动时 ,经口补充 Gln提高血浆 Gln浓度 ,可能与Gln被吸收入血有关 ;运动引起的 Gln合成减少不仅归因于底物的减少 ,还有合成酶活性降低的影响。

EFFECT OF GLUTAMINE SUPPLEMENTATION ON GLUTAMINE METABOLISM IN EXERCISING MICE

Objective: To approach the effects of glutamine supplementation on plasma and muscle levels of glutamine, and the activities of tissue glutamine synthetase and glutaminase after high intensity exercise. Methods: BAL/C mice were randomly divided into high intensity exercise(2% body weight load) and control groups to swim 2 hours per day for 8 weeks. Results: To compare with control group, high intensity exercise reduced glutamine levels in plasma and muscle by 74% (P<0.01) and 79%(P<0.01) respectively, and reduced the activity of glutamine synthetase in muscle by 33.5%(P<0.01) and enhanced the activity of glutaminase in lymphocytes by 315% (P<0.01).To compare with swimming group, glutamine supplementation enhanced glutamine levels in plasma and muscle by 142% (P<0.01) and 44.7% (P=0.056) respectively, and enhanced the activity of glutamine synthetase in muscle by 18.0% (P< 0.01 ) and reduced the activity of glutaminase in lymphocytes by 25.4%(P<0.01). Conclusion: In high intensity exercise, orally supplemented glutamine may raise plasma glutamine levels that might be in relation to glutamine absorbed into circulation; the reduction of glutamine synthesis induced by exercise may be attributed to not only decreased substrate availability but also to decreased glutamine synthetase activity.