Haus Jacob M, Carrithers John A, Carroll Chad C, Tesch Per A, Trappe Todd A
Human Performance Laboratory, Ball State Univ., Muncie, IN 47306, USA.
Am J Physiol Regul Integr Comp Physiol. 2007 Oct;293(4):R1722-7. doi: 10.1152/ajpregu.00292.2007. Epub 2007 Aug 1.
We examined the effects of 35 and 90 days of simulated microgravity with or without resistance-exercise (RE) countermeasures on the content of the general skeletal muscle protein fractions (mixed, sarcoplasmic, and myofibrillar) and specific proteins that are critical for muscle function (myosin, actin, and collagen). Subjects from two studies, using either unilateral lower limb suspension (ULLS) or bed rest (BR), comprised four separate groups: 35 days ULLS (n =11), 35 days ULLS+RE (n = 10), 90 days BR (n = 9), and 90 days BR+RE (n = 8). RE consisted of four sets of seven maximal concentric and eccentric repetitions of the quadriceps femoris muscles that were performed 2 or 3 times per week. Pre- and post-simulated weightlessness muscle biopsies were analyzed from the vastus lateralis of all groups and the soleus of the 35-day ULLS and 90-day BR groups. The general protein fractions and the specific proteins myosin, actin, and collagen of the vastus lateralis were unchanged (P > 0.05) in both control and countermeasures groups over 35 and 90 days, despite large changes in quadriceps femoris muscle volume (35 days ULLS: -9%, 35 days ULLS+RE: +8%; and 90 days BR: -18%, 90 days BR+RE: -1%). The soleus demonstrated a decrease in mixed (35 days ULLS: -12%, P = 0.0001; 90 days BR: -12%, P = 0.004) and myofibrillar (35 days ULLS: -12%, P = 0.009; 90 days BR: -8%, P = 0.04) protein, along with large changes in triceps surae muscle volume (35 days ULLS: -11%; 90 days BR: -29%). Despite the loss of quadriceps femoris muscle volume or preservation with RE countermeasures during simulated microgravity, the quadriceps femoris muscles are able to maintain the concentrations of the general protein pools and the main contractile and connective tissue elements. Soleus muscle protein composition appears to be disproportionately altered during long-duration simulated weightlessness.
我们研究了35天和90天模拟微重力条件下，有无抗阻运动（RE）对策对一般骨骼肌蛋白组分（混合蛋白、肌浆蛋白和肌原纤维蛋白）以及对肌肉功能至关重要的特定蛋白（肌球蛋白、肌动蛋白和胶原蛋白）含量的影响。两项研究中的受试者，分别采用单侧下肢悬吊（ULLS）或卧床休息（BR），分为四个独立组：35天ULLS组（n = 11）、35天ULLS+RE组（n = 10）、90天BR组（n = 9）和90天BR+RE组（n = 8）。RE包括四组，每组股四头肌进行七次最大程度的向心和离心重复收缩，每周进行2或3次。对所有组的股外侧肌以及35天ULLS组和90天BR组的比目鱼肌进行了模拟失重前后的肌肉活检分析。尽管股四头肌体积有较大变化（35天ULLS组：-9%，35天ULLS+RE组：+8%；90天BR组：-18%，90天BR+RE组：-1%），但在35天和90天期间，对照组和采取对策组的股外侧肌中一般蛋白组分以及肌球蛋白、肌动蛋白和胶原蛋白等特定蛋白均无变化（P>0.05）。比目鱼肌的混合蛋白（35天ULLS组：-12%，P = 0.0001；90天BR组：-12%，P = 0.004）和肌原纤维蛋白（35天ULLS组：-12%，P = 0.009；90天BR组：-8%，P = 0.04）含量下降，同时小腿三头肌体积有较大变化（35天ULLS组：-11%；90天BR组：-29%）。尽管在模拟微重力期间股四头肌体积减少或通过RE对策得以保持，但股四头肌仍能够维持一般蛋白池以及主要收缩和结缔组织成分的浓度。在长时间模拟失重期间，比目鱼肌的蛋白质组成似乎发生了不成比例的改变。
