Muchlinski Magdalena N, Hemingway Holden W, Pastor Juan, Omstead Kailey M, Burrows Anne M
Center for Anatomical Sciences, University of North Texas, Fort Worth, Texas.
Neuroscience, University of Kentucky, Lexington, Kentucky.
Anat Rec (Hoboken). 2018 Mar;301(3):528-537. doi: 10.1002/ar.23746.
Skeletal muscle fibers are often used to evaluate functional differences in locomotion. However, because there are energetic differences among muscle fiber cells, muscle fiber composition could be used to address evolutionary questions about energetics. Skeletal muscle is composed of two main types of fibers: Type I and II. The difference between the two can be reduced to how these muscle cells use oxygen and glucose. Type I fibers convert glucose to ATP using oxygen, while Type II fibers rely primarily on anaerobic metabolic processes. The expensive tissue hypothesis (ETH) proposes that the energetic demands imposed on the body by the brain result in a reduction in other expensive tissues (e.g., gastrointestinal tract). The original ETH dismisses the energetic demands of skeletal muscle, despite skeletal muscle being (1) an expensive tissue when active and (2) in direct competition for glucose with the brain. Based on these observations we hypothesize that larger brained primates will have relatively less muscle mass and a decrease in Type I fibers. As part of a larger study to test this hypothesis, we present data from 10 species of primates. We collected body mass, muscle mass, and biopsied four muscles from each specimen for histological procedures. We collected endocranial volumes from the literature. Using immunohistochemistry, a muscle fiber composition profile was created for each species sampled. Results show that larger brained primates have less muscle and fewer Type I fibers than primates with smaller brains. Results clarify the relationship between muscle mass and brain mass and illustrate how muscle mass could be used to address energetic questions. Anat Rec, 301:528-537, 2018. © 2018 Wiley Periodicals, Inc.
骨骼肌纤维常被用于评估运动功能的差异。然而，由于肌纤维细胞之间存在能量差异，肌纤维组成可用于解决有关能量学的进化问题。骨骼肌由两种主要类型的纤维组成：I型和II型。两者之间的差异可归结为这些肌细胞如何利用氧气和葡萄糖。I型纤维利用氧气将葡萄糖转化为三磷酸腺苷（ATP），而II型纤维主要依赖无氧代谢过程。昂贵组织假说（ETH）提出，大脑对身体施加的能量需求导致其他昂贵组织（如胃肠道）减少。最初的ETH忽略了骨骼肌的能量需求，尽管骨骼肌在活动时是一种昂贵的组织，并且与大脑直接竞争葡萄糖。基于这些观察结果，我们假设大脑较大的灵长类动物肌肉质量相对较小，I型纤维减少。作为检验这一假设的更大规模研究的一部分，我们展示了来自10种灵长类动物的数据。我们收集了体重、肌肉质量，并从每个标本中取了四块肌肉进行活检以进行组织学检查。我们从文献中收集了颅内容积。使用免疫组织化学方法，为每个采样物种创建了肌纤维组成概况。结果表明，大脑较大的灵长类动物比大脑较小的灵长类动物肌肉更少，I型纤维也更少。结果阐明了肌肉质量与脑质量之间的关系，并说明了肌肉质量如何可用于解决能量问题。《解剖学记录》，301:528 - 537，2018年。© 2018威利期刊公司。
