Andersen Jesper L
Copenhagen Muscle Research Center, Department of Molecular Muscle Biology, Rigshospitalet, Copenhagen, Denmark.
Scand J Med Sci Sports. 2003 Feb;13(1):40-7. doi: 10.1034/j.1600-0838.2003.00299.x.
This short review discusses changes in the fibre type distribution, myosin heavy chain isoform composition and histological appearance of the very elderly human skeletal muscle. Point of origin of the discussion comes from data that we have obtained from muscle biopsies from the vastus lateralis muscle of a group of frail very elderly subjects (age: 88 +/- 3 years, range 85-97). Myosin heavy chain composition of muscle homogenates and single fibres, fibre type distribution, fibre size and capillary density were examined and compared with muscle biopsies from the young vastus lateralis muscle. Histological preparations of the muscle biopsies from our elderly subjects showed extended "grouping" (Nygaard & Sanchez, Anat Rec 1992: 202: 451-459) of the fibre types as well as significant changes in the appearance and size of the individual muscle fibres. On average, the fibre type composition of our very elderly subjects do not seem to be different to what is observed in a corresponding young group when examined with ATPase histochemistry. Likewise, the MHC composition of the muscle homogenates is comparable to what is observed in young subjects. Nevertheless, a detailed examination of the MHC composition of single fibres from the old subjects revealed that the most prominent phenotype was fibres co-expressing MHC I and MHC IIA. This is very different from what is observed in the young muscle. Detailed investigation of longitudinally cut fibres indicated that some fibres in the very old muscle, in contrast to the young muscle, switch fibre type along the length of the fibre or contain areas or nuclear domains in which the MHC expression is different from the remaining part of the fibre.
这篇简短的综述讨论了高龄老人骨骼肌纤维类型分布、肌球蛋白重链亚型组成和组织学外观的变化。讨论的出发点来自于我们从一组体弱的高龄老人（年龄：88±3岁，范围85 - 97岁）股外侧肌肌肉活检中获得的数据。对肌肉匀浆和单根纤维的肌球蛋白重链组成、纤维类型分布、纤维大小和毛细血管密度进行了检测，并与年轻股外侧肌的肌肉活检结果进行了比较。我们老年受试者肌肉活检的组织学标本显示纤维类型出现广泛的“群组化”（Nygaard和Sanchez，《解剖学记录》1992年：202: 451 - 459），以及单个肌纤维的外观和大小发生显著变化。平均而言，当用ATP酶组织化学检测时，我们高龄老人的纤维类型组成似乎与相应年轻组中观察到的情况没有差异。同样，肌肉匀浆的MHC组成与年轻受试者中观察到的情况相当。然而，对老年受试者单根纤维的MHC组成进行详细检查发现，最突出的表型是同时表达MHC I和MHC IIA的纤维。这与年轻肌肉中观察到的情况非常不同。对纵向切割纤维的详细研究表明，与年轻肌肉相比，高龄老人肌肉中的一些纤维在纤维长度方向上会转换纤维类型，或者包含MHC表达与纤维其余部分不同的区域或核域。
