title: Effect of Immobilization on Insoluble Collagen Concentration and Type I and Type III Collagen Isoforms of Rat Soleus Muscle.
abstract: Immobilization is often associated with decreased muscle elasticity. This condition is known as muscle contracture; however, the mechanism remains unclear. The purpose of this study was to clarify the mechanism governing muscle contracture in rat soleus muscle by identifying changes in ankle joint mobility, insoluble collagen concentration and type I and type III collagen isoforms following 1- and 3-week immobilizations. Following a 1-week immobilization, range of motion (ROM) of dorsiflexion declined to 90% of the control value; additionally, ROM dropped to 67.5% of the control value after a 3-week immobilization. This finding suggested that ankle joint mobility decreases in conjunction with extended periods of immobilization. Insoluble collagen concentration in soleus muscles, which was unchanged after 1 week of immobilization, increased 3 weeks after immobilization. These results may be indicative of collagen fibers with strong intermolecular cross-links contained in the muscle was made increased relatively by 3 weeks of immobilization. Therefore, the change in intermolecular cross-links may be significant in terms of progress of muscle contracture with longer periods of immobilization. On the other hand, the ratio of type III to type I collagen isoforms in muscular tissue increased following a 1-week immobilization; moreover, this ratio remained constant after 3 weeks of immobilization. These data suggested that muscle immobilization may induce type III collagen isoform expression. The increase in the ratio of type III to type I collagen isoforms do not change in parallel with the increase in the limitation in ROM; however, this phenomenon probably is not closely related to the progress of muscle contracture. The change of collagen isoform in immobilized muscle may be involved in the mechanism governing the progression of muscle fibrosis.
authors: Department of Rehabilitation Science, Faculty of Human Health, Nagoya Gakuin University, Aichi 480-1298, Japan ; Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa 920-1192, Japan.
authors: Itaru
authors: I
authors: Hibino
authors: Division of Physical Therapy and Occupational Therapy Science, Graduate School of Health Sciences, Nagasaki University, Nagasaki 852-8520, Japan.
authors: Minoru
authors: M
authors: Okita
authors: Program in Physical and Occupational Therapy, Graduate School of Health Sciences, Nagoya University, Nagoya 461-8673, Japan.
authors: Takayuki
authors: T
authors: Inoue
authors: Faculty of Care and Rehabilitation, Seijoh University, Aichi 476-8588, Japan.
authors: Yasuhiro
authors: Y
authors: Banno
authors: Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa 920-1192, Japan.
authors: Masahiro
authors: M
authors: Hoso
keywords: collagen; immobilization; muscle contracture