Evidence for Two Distinct Cross-Bridge Populations in Tetanized Frog Muscle Fibers Stretched with Moderate Velocities

  • Takakazu Kobayashi
  • Shoichi Kosuge
  • Haruo Sugi
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 453)


When a tetanized frog skeletal muscle fiber is stretched with moderate velocities (<1 L 0/s), the tension developed above the level of isometric tension starts to decay after a sudden reduction of stretch velocity by more than 40–50%, though the fiber is still being stretched. We analyzed the decay of tension responses caused by the sudden reduction of stretch velocity, by applying three different types of stretch, i.e. a 1.5% stretch with velocity V1 (stretch 1), a 1.5% stretch with velocity V2 < V1 (stretch 2), and a 3% stretch consisting of stretches 1 and 2 applied in succession (stretch 3) and comparing the corresponding tension responses, TR 1, TR 2 and TR 3. It was found that TR 3 to stretch 3 was equal to algebraical sum of TR 1 to the preceding stretch 1 and TR 2 to the subsequent stretch 2. In other words, TR 2 started on the falling tension baseline equal to the decay of TR 1 after completion of stretch 1, These results can be explained by assuming two distinct cross-bridge populations mechanically acting in parallel with each other.


Thin Filament Myosin Head Tension Response Isometric Tension Sudden Reduction 


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  1. 1.
    Abbott, B.C. & Aubert, X.M. J. Physiol. 117, 77–86 (1952).PubMedGoogle Scholar
  2. 2.
    Hill, A.V. & Howarth, J.V. Proc. Roy. Soc. B151, 169–193 (1959).Google Scholar
  3. 3.
    Curtin, N.A. & Davies, R.E. Cold Spring Harb. Symp. Quant. Biol. 37, 619–626 (1973).CrossRefGoogle Scholar
  4. 4.
    Huxley, A.F. Prog. Biophys. Biophys. Chem.l, 255–318 (1957).Google Scholar
  5. 5.
    Huxley, H.E. in The Cell, (eds. Brahet, J. & Mirsky, A.E.) 365–481 (Academic Press, New York, 1960)Google Scholar
  6. 6.
    Sugi, H. J. Physiol. 225, 237–253 (1972).PubMedGoogle Scholar
  7. 7.
    Kobayashi, T., Kosuge, S., Narushima, K. & Sugi, H. submitted, 1998Google Scholar
  8. 8.
    Kobayashi, T., Kosuge, S., Shimada, M. & Sugi, H. J. Muscle Res. Cell Motil. 17, 277–278 (1996).CrossRefGoogle Scholar
  9. 9.
    Gasser, H.S. & Hill, A.V. Proc. Roy. Soc. B96, 398–437 (1924).Google Scholar
  10. 10.
    Dillon, P.F., Aksoy, M.O., Driska, S.P. & Murphy, R.A. Science 211, 495–497 (1981).PubMedCrossRefGoogle Scholar
  11. 11.
    Twarog, B.M. Physiol. Rev. 56, 829–838 (1976).PubMedGoogle Scholar
  12. 12.
    Amemiya, Y., Iwamoto, H., Kobayashi, T., Sugi, H., Tanaka, H. & Wakabayashi, K. J. Physiol. 407, 231–241 (1988).PubMedGoogle Scholar
  13. 13.
    Kobayashi, T., Wakabayashi, K., Kosuge, S. & Sugi, H. J. Muscle Res. Cell Motil. 18, 486 (1997).Google Scholar

Copyright information

© Plenum Press, New York 1998

Authors and Affiliations

  • Takakazu Kobayashi
    • 1
  • Shoichi Kosuge
    • 1
  • Haruo Sugi
    • 1
  1. 1.Department of Physiology School of MedicineTeikyo UniversityItabashi-ku, TokyoJapan

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