Spontaneous oscillatory contraction of sarcomeres in skeletal myofibrils

Nobuyuki Okamura, Shin'ichi Ishiwata

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    Abstract

    We found that the lengths of all sarcomeres spontaneously oscillated in an isolated skeletal myofibril, when both ends were fixed, submillimolar to millimolar concentrations of ATP, ADP and inorganic phosphate (Pi) were present, and Ca2+ was removed. Narrowing and widening of an H-zone and an I-band were observed corresponding to the shortening and lengthening of a sarcomere, suggesting that thick and thin filaments slide past each other. The oscillation of each sarcomere was asymmetrical, consisting of a rapid lengthening phase and a slow shortening phase. The period of oscillation was about 3 s; the peak-to-peak amplitude of oscillation reached as much as 30% of the average sarcomere length. The propagation of the sarcomere oscillation along the long axis of the myofibril was observed occasionally in single myofibrils and frequently in bundles of myofibrils. The 'state'-diagram showing the concentration range of ADP and Pi in which contraction, oscillation or relaxation of myofibrils occurs in the presence of ATP and the absence of Ca2+ suggested that the oscillation is a third state of skeletal muscle located in between the contracting and relaxing states.

    Original languageEnglish
    Pages (from-to)111-119
    Number of pages9
    JournalJournal of Muscle Research and Cell Motility
    Volume9
    Issue number2
    DOIs
    Publication statusPublished - 1988 Apr

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    ASJC Scopus subject areas

    • Physiology
    • Endocrinology
    • Clinical Biochemistry
    • Cell Biology

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