2000 Fiscal Year Final Research Report Summary
Effects of exercise training on the ultrastructural alterations of membrane systems involved in excitation-contraction coupling during contraction in skeletal muscle.
| Project/Area Number |
10480009
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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 |
体育学
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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 Physiological Sciences Associate Professor, 体育学部, 助教授 (00206963)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIOKA Toshitada Aomori University of Health and Welfare Vice President, 副学長 (50056933)
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| Project Period (FY) |
1998 – 2000
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| Keywords | exercise / excitation-cont raction coupling / ultrastructure / transverse tubules / sarcoplasmic reticulum / triad / electron microscope / skeletal muscle |
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| Research Abstract |
Excitation-contraction (E-C) coupling is the series of steps that leads from the electrical event at the surface if the muscle fiber (excitation) to contraction of the muscle fibers. Two major membrane components directly concerned with the E-C coupling process : transverse (T) tubules and sarcoplasmic reticulum (SR). T tubules are invaginations of the surface membrane which penetrate into the muscle fibers and form transverse networks at precisely repeated intervals. T tubules transmit the electrical signal to the center of the muscle fiber. The SR is an internal membrane system equivalent to the endoplasmic reticulum of other cells, which is located in the space between the myofibrils. The SR sequesters calcium (Ca^<2+>) from the myofibrils. T tubules and SR form specialized junctions, the triads. Physiological evidence suggests the possibility that the E-C coupling failure with eccentric contraction-induced muscle injury is due to structural and morphological damage to membrane systems directly associated with the E-C coupling processes within skeletal muscle fibres. We observed the ultrastructural features of the membrane systems of rat fast-twitch (FT) and slow-twitch (ST) muscle fibres involved in E-C coupling following level and downhill running exercise. There were four obvious ultrastructural changes in the arrangement of the T tubules and the disposition of triads after the downhill running exercise : (1) an increase in the numbers of longitudinal segments of the T tubule network, (2) changes in the direction and disposition of triads, (3) the appearance of caveolar clusters, and (4) the appearance of pentads and heptads. These observations also support the idea that eccentric-exercise-induced E-C coupling failure is due to physical and chemical disruptions of the membrane systems involved in the E-C coupling process in skeletal muscle.
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[Publications] Protasi, F., Takekura, H., Wang, Y., Chen, S.R.W., Meissner, G., Allen, P.D.and Franzini-Armstrong, C.: "RyR1 and RyR3 have different roles in the assembly of calcium release units of skeletal muscle."Biophys.J.. 79. 2494-2508 (2000)
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