Varnier M, Leese G P, Thompson J, Rennie M J
Department of Anatomy and Physiology, University of Dundee, Scotland, United Kingdom.
Am J Physiol. 1995 Aug;269(2 Pt 1):E309-15. doi: 10.1152/ajpendo.1995.269.2.E309.
To determine whether glutamine can stimulate human muscle glycogen synthesis, we studied in groups of six subjects the effect after exercise of infusion of glutamine, alanine+glycine, or saline. The subjects cycled for 90 min at 70-140% maximal oxygen consumption to deplete muscle glycogen; then primed constant infusions of glutamine (30 mg/kg; 50 mg.kg-1.h-1) or an isonitrogenous, isoenergetic mixture of alanine+glycine or NaCl (0.9%) were administered. Muscle glutamine remained constant during saline infusion, decreased 18% during alanine+glycine infusion (P < 0.001), but rose 16% during glutamine infusion (P < 0.001). By 2 h after exercise, muscle glycogen concentration had increased more in the glutamine-infused group than in the saline or alanine+glycine controls (+2.8 +/- 0.6, +0.8 +/- 0.4, and +0.9 +/- 0.4 mumol/g wet wt, respectively, P < 0.05, glutamine vs. saline or alanine+glycine). Labeling of glycogen by tracer [U-13C]glucose was similar in glutamine and saline groups, suggesting no effect of glutamine on the fractional rate of blood glucose incorporation into glycogen. The results suggest that, after exercise, increased availability of glutamine promotes muscle glycogen accumulation by mechanisms possibly including diversion of glutamine carbon to glycogen.
为了确定谷氨酰胺是否能刺激人体肌肉糖原合成，我们以每组六名受试者为对象，研究了运动后输注谷氨酰胺、丙氨酸+甘氨酸或生理盐水的效果。受试者以最大耗氧量的70 - 140%进行90分钟的骑行，以耗尽肌肉糖原；然后给予谷氨酰胺（30 mg/kg；50 mg·kg⁻¹·h⁻¹）或丙氨酸+甘氨酸或NaCl（0.9%）的等氮、等能量混合物的首剂持续输注。输注生理盐水期间肌肉谷氨酰胺保持不变，输注丙氨酸+甘氨酸期间下降18%（P < 0.001），但输注谷氨酰胺期间上升16%（P < 0.001）。运动后2小时，输注谷氨酰胺组的肌肉糖原浓度增加幅度大于生理盐水或丙氨酸+甘氨酸对照组（分别为+2.8±0.6、+0.8±0.4和+0.9±0.4 μmol/g湿重，P < 0.05，谷氨酰胺组与生理盐水或丙氨酸+甘氨酸组相比）。用示踪剂[U-¹³C]葡萄糖对糖原进行标记在谷氨酰胺组和生理盐水组中相似，表明谷氨酰胺对血糖掺入糖原的分数率没有影响。结果表明，运动后谷氨酰胺可用性的增加通过可能包括将谷氨酰胺碳转移到糖原的机制促进肌肉糖原积累。
