Wu G Y, Thompson J R
Department of Animal Science, University of Alberta, Edmonton, Canada.
Biochem J. 1990 Jan 15;265(2):593-8. doi: 10.1042/bj2650593.
The effect of glutamine on the rates of protein synthesis and degradation was studied in isolated chick extensor digitorum communis muscles incubated in the presence of plasma concentrations of amino acids. Addition of 0.5-15 mM-glutamine increases (P less than 0.01) intracellular glutamine concentrations by 31-670%. There is a positive relationship (r = 0.975, P less than 0.01) between intracellular glutamine concentration and the rate of muscle protein synthesis measured by the incorporation of [3H]phenylalanine. The stimulating effect of 15 mM-glutamine on protein synthesis was decreased from 58 to 19% in muscles incubated in the absence of tyrosine. The rates of protein degradation, estimated from [3H]phenylalanine release from muscle proteins prelabelled in vivo, decreased (P less than 0.05) by 15-30% in the presence of 4-15 mM-glutamine when compared with muscles incubated in the presence of physiological concentrations of glutamine (0.5-1 mM). Glutamine concentrations ranging from 2 to 15 mM appear to have an overall anabolic effect on chick skeletal muscles incubated in vitro.
在含有血浆浓度氨基酸的条件下，对离体鸡趾长伸肌进行孵育，研究了谷氨酰胺对蛋白质合成和降解速率的影响。添加0.5 - 15 mM的谷氨酰胺可使细胞内谷氨酰胺浓度增加31 - 670%（P < 0.01）。通过[³H]苯丙氨酸掺入法测定的细胞内谷氨酰胺浓度与肌肉蛋白质合成速率之间存在正相关关系（r = 0.975，P < 0.01）。在无酪氨酸孵育的肌肉中，15 mM谷氨酰胺对蛋白质合成的刺激作用从58%降至19%。与在生理浓度谷氨酰胺（0.5 - 1 mM）存在下孵育的肌肉相比，在4 - 15 mM谷氨酰胺存在下，根据体内预标记肌肉蛋白质释放的[³H]苯丙氨酸估算的蛋白质降解速率降低了15 - 30%（P < 0.05）。2至15 mM的谷氨酰胺浓度似乎对体外孵育的鸡骨骼肌具有总体合成代谢作用。
