Greising Sarah M, Medina-Martínez Juan S, Vasdev Amrit K, Sieck Gary C, Mantilla Carlos B
Department of Physiology and Biomedical Engineering, Mayo Clinic, 200 First Street SW, SMH Jo 4-184, Rochester, Minnesota, 55905, USA.
Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota, USA.
Muscle Nerve. 2015 Jul;52(1):76-82. doi: 10.1002/mus.24641. Epub 2015 Jun 1.
Sarcopenia likely comprises muscle fiber denervation and re-innervation, resulting in clustering of muscle fibers of the same type (classified by myosin heavy chain isoform composition). Development of methodology to quantitatively evaluate clustering of muscle fibers according to fiber type is necessary.
Fiber type specific immunofluorescence histology was used to quantify fiber clustering in murine diaphragm muscle (n = 15) at ages 6 and 24 months.
With age, fiber type clustering is evidenced by fiber type specific changes in distances between fibers, specifically a 14% decrease to the closest fiber for type I and 24% increase for type IIx and/or IIb fibers (P < 0.001). Additionally, a 34% increase to the 3 closest type IIx and/or IIb fibers was found (P < 0.001).
This novel method of analyzing fiber type clustering may be useful in examining pathophysiological conditions of motor unit loss in neuromuscular disorders, myopathies, dystrophies, injuries, or amyotrophic lateral sclerosis.
肌肉减少症可能包括肌纤维去神经支配和重新支配，导致同类型肌纤维（根据肌球蛋白重链异构体组成分类）聚集。开发根据纤维类型定量评估肌纤维聚集的方法很有必要。
采用纤维类型特异性免疫荧光组织学方法，对6个月和24个月龄小鼠膈肌（n = 15）中的纤维聚集进行定量分析。
随着年龄增长，纤维类型聚集表现为纤维间距离的纤维类型特异性变化，具体而言，I型纤维到最近纤维的距离减少了14%，IIx和/或IIb型纤维增加了24%（P < 0.001）。此外，发现到最近的3根IIx和/或IIb型纤维的距离增加了34%（P < 0.001）。
这种分析纤维类型聚集的新方法可能有助于检查神经肌肉疾病、肌病、营养不良、损伤或肌萎缩侧索硬化症中运动单位丧失的病理生理状况。
