Effects of Heat Stress on Muscle Fibers Damage in Reloading after Immobilized Rat Soleus Muscle

DOI IR HANDLE 19 References Open Access
  • BANNO Yasuhiro
    Division of Physical Therapy, Faculty of Care and Rehabilitaion, Seijoh University
  • OKITA Minoru
    Unit of Physical and Occupational Therapy, Nagasaki University Graduate School of Biomedical Sciences
  • SUZUKI Shigeyuki
    Program in Physical and Occupational Therapy, Graduate School of Health Sciences, Nagoya University
  • INOUE Takayuki
    Program in Physical and Occupational Therapy, Graduate School of Health Sciences, Nagoya University
  • YOSHIDA Nao
    Department of Rehabilitation, Nagasaki Memorial Hospital
  • KOBAYASHI Yui
    Department of Rehabilitation, Sakura Hospital
  • TAKANAMI Mika
    Department of Rehabilitation, Sakura Hospital
  • HAYASHI Ayako
    Department of Rehabilitation, Kanzakichuou Hospital

Bibliographic Information

Other Title
  • ギプス固定後の再荷重によるラットヒラメ筋の筋線維損傷に対する温熱負荷の影響

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Abstract

Background: The purpose of the present study was to determine whether heat stress is preventive for muscle fiber injury induced by reloading after immobilization in rat soleus muscle. <br>Methods: Forty-three male 8-week-old Wistar rats were used. Rats were divided randomly into control (C, n=15), immobilized followed by normal recovery (IR, n=14), and immobilized followed by heat stress before reloading (IH, n=14) groups. Bilateral ankles of each rat in the IR and IH groups were fixed in full planter flexion with a plaster cast for 4 weeks. Immediately after 4 weeks of immobilization, reloading was allowed for rats in the IR group. Rats in the IH group were first exposed to heat stress (41℃ for 60 min) in an incubator under anesthesia 2 days before reloading. At 0, 1 and 3 days after reloading, both soleus muscles in all groups were excised and weighed. Frozen sections of these muscles were stained with hematoxylin-eosin, the number of necrotic muscle fibers was counted, and muscle fiber diameters were measured. Moreover, Hsp70 contents in muscle tissue were measured by using the Western blot method. <br>Results: Immediately after remobilization, Heat shock protein (Hsp) 70 levels were significantly increased in IH groups compared with IR groups. Muscle fiber atrophy was seen in IR and IH groups. In 3 days after reloading, the number of necrotic muscle fibers was significantly increased in IR compared with IH groups. <br>Conclusions: The present findings suggest that heat stress prior to reloading induces expression of Hsp70 and leads to protective effect against soleus muscle injury induced by reloading after immobilization.

Journal

  • Physical Therapy Japan

    Physical Therapy Japan 36 (2), 33-40, 2009-04-20

    Japanese Society of Physical Therapy

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