| Project/Area Number |
17300210
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Sports science
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| Research Institution | National Institute of Fitness and Sports in Kanoya |
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Principal Investigator |
TAKEKURA Hiroaki National Institute of Fitness and Sports in Kanoya, Sports Performance, Professor (00206963)
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| Co-Investigator(Kenkyū-buntansha) |
KASUGA Norikatsu Aichi University of Education, Physical Education, Professor (60152659)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥15,940,000 (Direct Cost: ¥15,100,000、Indirect Cost: ¥840,000)
Fiscal Year 2007: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
Fiscal Year 2006: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2005: ¥7,500,000 (Direct Cost: ¥7,500,000)
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| Keywords | skeletal muscle / membrane system / excitation contraction coupling / transverse tubule / sarcoplasmic reticulum / triad / electron microscope / development / myotendinous junction / Ca^<2+>チャンネル / Ca^<2+> Release Units |
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| Research Abstract |
The transverse (t) -tubule is responsible for the rapid inward spread of excitation from the sarcolemma to the inside of the muscle fiber, and the compartments of the t-tubule become highly and regularly organized during development. Although it is known that skeletal muscle fibers lengthen by adding sarcomeres at the myotendinous junction (MTJ) during development, no specific model exists for the assembly of new t-tubule architecture at the MTJ. We performed an electron-microscopic examination of the assembly of t-tubule architecture at the MTJ in developing rat skeletal muscle fibers. Although the longitudinally oriented t-tubule elements represent only a small fraction of the total t-tubule system in adult muscle fibers, they were observed at both A-band and I-band regions of middle and MTJ regions in early developmental stages, and gradually disappeared in the middle regions of muscle fibers during development ; however, they remained in the MTJ even in adult muscle fibers. The frequency of pentads and heptads (two or three t-tubule elements with three or four elements of terminal cisternae, closely aligned with terminal cisternae of the sarcoplasmic reticulum) decreased during development, with sudden decrease between 7 and 10 weeks of age in the middle regions. Interestingly, although the frequency of decrease appeared to be higher in the middle region than in the MTJ regions in early (3- to 7-week) development, this pattern reversed, and the frequency of decrease was higher in the MTJ in later development (after 10 weeks of age). The MTJ maintained the features of immature membrane systems involved in e-c coupling much longer than the middle region of the fiber during development. The assembly of t-tubule architecture during postnatal development thus follows different processes in the middle and MTJ regions of skeletal muscle fibers.
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