Effects of Immobillzation on Rat Soleus Muscle at Neutral and Plantarflexed Positions of the Ankle Joint

本研究では, 関節の固定肢位の違いが筋線維, ならびに筋内膜コラーゲン線維におよぼす影響を形態学的に検討した。実験動物は, ウィスタ一系雄ラット8匹で, 右足関節を中間肢位と底屈肢位で固定した2群に分け, 4週間のギプス固定後, ヒラメ筋を摘出し, 微細形態を観察した。底屈肢位は, 中間肢位に比べ廃用性筋萎縮の程度が著しく, 筋節長の短縮や微細構造に退行性変化が認められた。また, 筋内膜コラーゲン線維網の構築学的変化も著しかった。このことから, 筋性拘縮の要因には, 筋線維自体の短縮や退行性変化に加え, コラーゲン線維網の構築学的変化が関連していると考えられる。また, 骨格筋の伸張は, 廃用性筋萎縮や筋, 筋膜の短縮を防ぐ重要なものであると推察される。The purpose of this study was to determine the effect of immobilization on muscle fibers and co11agen fibril11es in the endomysium of the rat soleus muscle at neutral and plantarflexed positions of the ankle joint. Eight male Wistar rats were divided into two groups.In one group (n=3), the ankle joint was fixed in the neutral position and in the other (n=5), in the plantarflexed position for four weeks. The soleus muscle was then biopsied and morphological study was conducted using a light and electron microscope. Collagen fibrilles in the endomysium were observed with a scanning electron microscope. The soleus muscle in the planterflexed position became more atropied compared to neutral position. Sarcomere lengths decreased, and morphologic changes in muscle fibers were evident. The transverse component of collagen fibrilles increased in the planterflexed position. The rearrangement of collagen fibrilles was considered to affect muscle contracture, and muscle stretch may play preventive roles in disuse atrophy, shortening of muscle fibers, and endomysium during immobilization