Histochemical Responses of Human Soleus Muscle Fibers to Long-Term Bedrest with or without Countermeasures
| Autor: | Inessa Kozlovskaya, Katsumasa Yamashita-Goto, Ryutaro Izumi, Yoshinobu Ohira, Tomoo Yoshinaga, Boris Shenkman, Makoto Ohara, C. Sekiguchi, Koh Yasukawa, Ikuya Nonaka, Toshitada Yoshioka |
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| Rok vydání: | 2000 |
| Předmět: |
Adult
Male medicine.medical_specialty Supine position Physiology Biopsy Muscle Fibers Skeletal Knee extension Atrophy medicine Humans Fiber Muscle Skeletal Cell Size Soleus muscle Myosin Heavy Chains Fiber type business.industry Fiber size General Medicine Space Flight medicine.disease Surgery medicine.anatomical_structure Anesthesia Space Suits Ankle business Bed Rest |
| Zdroj: | The Japanese Journal of Physiology. 50:41-47 |
| ISSN: | 0021-521X |
| DOI: | 10.2170/jjphysiol.50.41 |
| Popis: | Effects of 2- or 4-month bedrest in -6 degrees head-down tilt position with or without countermeasures on the histochemical properties of fiber phenotype and cross-sectional area (CSA) were studied in human soleus. The CSAs in slow fibers decreased approximately 32% during 4-month bedrest. This reduction was normalized after 1-month recovery. Although the reduction of percent slow fibers was not significant statistically, the percent intermediate fibers was significantly elevated 4 months after bedrest. Such shift in fiber type was not normalized following 1-month recovery. Effects of wearing an anti-g Penguin suit which has a modest, but continuous resistance at the knee and ankle (Penguin-1) or with knee resistance without loading on the ankle (Penguin-2) for 10 consecutive hours daily were also investigated during approximately 2 months of bedrest. The subjects performed knee extension and flexion for the last 15 min of each hour while in a supine position in bed. Bedrest-induced fiber atrophy was prevented in the Penguin-1 group but not the Penguin-2 group. Transformation of fiber type was not prevented in either Penguin suit group. It is suggested that long-term bedrest causes an atrophy and a shift of fiber phenotype toward fast-twitch type in human soleus. Data also indicated that loading on the muscle is an effective countermeasure for prevention of fiber atrophy but not fiber-type transformation. |
| Databáze: | OpenAIRE |
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