Abstract
1. The relation between sarcomere length and tetanic tension at various states of shortening was investigated in single frog semitendinosus fibres that were subjected to different degrees of prestretch (2·45-3·0 μ).
2. The capacity to produce tension changed in a characteristic way during shortening, the tension output at each length being determined by the actual sarcomere spacing without reference to the striation spacing at the onset of contraction.
3. The capacity to shorten against a given load was independent of the initial striation spacing, provided the load was not great enough to cause fatigue of the fibre.
4. The findings strongly suggest that the functionally relevant structure of the contractile system of the intact muscle cell is always in the same state at a given sarcomere length independent of how the previous length change has been achieved, by passive extension at rest or by active shortening from a prestretched position. This probably means that contraction involves a structural change of the contractile system, which, at least in so far as it is of relevance to function, is a true reversal of the change produced by passive extension of the resting fibre. These aspects of the contractile behaviour of the intact muscle fibre are in full accord with the concepts of the sliding-filament hypothesis of muscular contraction.
Full text
PDF











Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- ALEXANDER R. S., JOHNSON P. D., Jr MUSCLE STRETCH AND THEORIES OF CONTRACTION. Am J Physiol. 1965 Mar;208:412–416. doi: 10.1152/ajplegacy.1965.208.3.412. [DOI] [PubMed] [Google Scholar]
- CARLSEN F., KNAPPEIS G. G., BUCHTHAL F. Ultrastructure of the resting and contracted striated muscle fiber at different degrees of stretch. J Biophys Biochem Cytol. 1961 Oct;11:95–117. doi: 10.1083/jcb.11.1.95. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HUXLEY A. F. Muscle structure and theories of contraction. Prog Biophys Biophys Chem. 1957;7:255–318. [PubMed] [Google Scholar]
- HUXLEY A. F., NIEDERGERKE R. Structural changes in muscle during contraction; interference microscopy of living muscle fibres. Nature. 1954 May 22;173(4412):971–973. doi: 10.1038/173971a0. [DOI] [PubMed] [Google Scholar]
- HUXLEY A. F., PEACHEY L. D. The maximum length for contraction in vertebrate straiated muscle. J Physiol. 1961 Apr;156:150–165. doi: 10.1113/jphysiol.1961.sp006665. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HUXLEY H. E. The double array of filaments in cross-striated muscle. J Biophys Biochem Cytol. 1957 Sep 25;3(5):631–648. doi: 10.1083/jcb.3.5.631. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HUXLEY H., HANSON J. Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation. Nature. 1954 May 22;173(4412):973–976. doi: 10.1038/173973a0. [DOI] [PubMed] [Google Scholar]
- PODOLSKY R. J. THE MAXIMUM SARCOMERE LENGTH FOR CONTRACTION OF ISOLATED MYOFIBRILS. J Physiol. 1964 Jan;170:110–123. doi: 10.1113/jphysiol.1964.sp007317. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PODOLSKY R. J. The chemical thermodynamics and molecular mechanism of muscular contraction. Ann N Y Acad Sci. 1959 Feb 6;72(12):522–537. doi: 10.1111/j.1749-6632.1959.tb44180.x. [DOI] [PubMed] [Google Scholar]

