Human soleus and vastus lateralis muscle protein metabolism with an amino acid infusion
Human soleus and vastus lateralis muscle protein metabolism with an amino acid infusion
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DOI：
10.1152/ajpendo.00393.2004
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发表时间：
2005-03-01
影响因子：
5.1
通讯作者：
Trappe, TA
中科院分区：
文献类型：
--
作者：
Carroll, CC;Fluckey, JD;Trappe, TA
与大腿肌肉相比，在运动和卧床休息的人群中，小腿肌肉对阻力运动的反应较弱，这显然是由于肌肉在蛋白质代谢方面的特异性差异。我们选择评估使用氨基酸提高比目鱼肌蛋白质合成的功效，因为氨基酸已被证明在股外侧肌中具有强大的合成代谢作用。测定10例患者（28+/-1年）注射混合氨基酸前后比目鱼肌和股外侧肌混合肌蛋白合成情况。核糖体蛋白p70 S6激酶（p70(S6K)）的磷酸化；Thr(389))和真核起始因子4e结合蛋白-1 （4E-BP1; Thr(37/46)）也在静息和氨基酸输注3小时后进行评估。基础蛋白质合成相似（P=0.126），氨基酸对股外侧肌（0.043+/-0.011%/h）和比目鱼肌（0.032+/-0.017%/h）蛋白质合成的刺激程度相似（P=0.004）。p70(S6K) （P=0.443）和4E-BP1 （P=0.192）的磷酸化均未升高；相比股外侧肌，比目鱼肌含有更多的总4E-BP1 （P=0.002）和磷酸化4E-BP1 （P=0.013）。这些数据支持需要进一步研究补充氨基酸作为一种手段来弥补在流动个体和暴露于长时间卸载的个体中小腿阻力运动的有效性降低。比目鱼肌中较大的4E-BP1表明在人类骨骼肌中存在一般翻译起始机制的肌肉特异性分布。
The calf muscles, compared with the thigh, are less responsive to resistance exercise in ambulatory and bed-rested individuals, apparently due to muscle-specific differences in protein metabolism. We chose to evaluate the efficacy of using amino acids to elevate protein synthesis in the soleus, because amino acids have been shown to have a potent anabolic effect in the vastus lateralis. Mixed muscle protein synthesis in the soleus and vastus lateralis was measured before and after infusion of mixed amino acids in 10 individuals (28+/-1 yr). Phosphorylation of ribosomal protein p70 S6 kinase (p70(S6K); Thr(389)) and eukaryotic initiation factor 4E-binding protein-1 (4E-BP1; Thr(37/46)) was also evaluated at rest and after 3 h of amino acid infusion. Basal protein synthesis was similar (P=0.126), and amino acids stimulated protein synthesis to a similar extent (P=0.004) in the vastus lateralis (0.043+/-0.011%/h) and soleus (0.032+/-0.017%/h). Phosphorylation of p70(S6K) (P=0.443) and 4E-BP1 (P=0.192) was not increased in either muscle; however, the soleus contained more total (P=0.002) and phosphorylated (P=0.013) 4E-BP1 than the vastus lateralis. These data support the need for further study of amino acid supplementation as a means to compensate for the reduced effectiveness of calf resistance exercise in ambulatory individuals and those exposed to extended periods of unloading. The greater 4E-BP1 in the soleus suggests that there is a muscle-specific distribution of general translational initiation machinery in human skeletal muscle.