Pederson Bartholomew A, Cope Carlie R, Schroeder Jill M, Smith Micah W, Irimia José M, Thurberg Beth L, DePaoli-Roach Anna A, Roach Peter J
Department of Biochemistry and Molecular Biology and Indiana University Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, Indiana 46202-5122, USA.
J Biol Chem. 2005 Apr 29;280(17):17260-5. doi: 10.1074/jbc.M410448200. Epub 2005 Feb 11.
The glucose storage polymer glycogen is generally considered to be an important source of energy for skeletal muscle contraction and a factor in exercise endurance. A genetically modified mouse model lacking muscle glycogen was used to examine whether the absence of the polysaccharide affects the ability of mice to run on a treadmill. The MGSKO mouse has the GYS1 gene, encoding the muscle isoform of glycogen synthase, disrupted so that skeletal muscle totally lacks glycogen. The morphology of the soleus and quadriceps muscles from MGSKO mice appeared normal. MGSKO-null mice, along with wild type littermates, were exercised to exhaustion. There were no significant differences in the work performed by MGSKO mice as compared with their wild type littermates. The amount of liver glycogen consumed during exercise was similar for MGSKO and wild type animals. Fasting reduced exercise endurance, and after overnight fasting, there was a trend to reduced exercise endurance for the MGSKO mice. These studies provide genetic evidence that in mice muscle glycogen is not essential for strenuous exercise and has relatively little effect on endurance.
葡萄糖储存聚合物糖原通常被认为是骨骼肌收缩的重要能量来源以及运动耐力的一个影响因素。利用一种缺乏肌肉糖原的基因改造小鼠模型来研究这种多糖的缺失是否会影响小鼠在跑步机上跑步的能力。MGSKO小鼠的GYS1基因（编码糖原合酶的肌肉异构体）被破坏，从而使骨骼肌完全缺乏糖原。MGSKO小鼠的比目鱼肌和股四头肌形态正常。将MGSKO基因敲除小鼠与其野生型同窝小鼠一起运动至疲惫。与野生型同窝小鼠相比，MGSKO小鼠完成的工作量没有显著差异。运动期间MGSKO小鼠和野生型动物消耗的肝糖原量相似。禁食会降低运动耐力，过夜禁食后，MGSKO小鼠有运动耐力降低的趋势。这些研究提供了遗传学证据，表明在小鼠中肌肉糖原对于剧烈运动并非必不可少，并且对耐力的影响相对较小。
