E-ISSN 2231-3206 | ISSN 2320-4672
Required files to uploaded
New hypothesis for mechanism of sliding filament theory of skeletal muscle contraction
Shreechakradhar U Mungal, Sushil P Dube, Anandkumar Dhole, Uddhav Mane, Anil K Bondade.
Background: Current understanding of skeletal muscle contraction is based on the sliding filament theory proposed independently by A.F. Huxley and H.E. Huxley (1954). The sliding filament theory very well explained shortening of skeletal muscle during contraction with reference to a single sarcomere with movement of Z discs toward center of that particular sarcomere. However, when we consider shortening of multiple sarcomeres in a myofibril arranged in series, the sliding filament theory fails to justify the movement of Z discs as each Z disc is being pulled in opposite direction by myosin heads of adjacent sarcomeres.
Aims & Objectives: To find out alternate possible mechanism of Z disc movement on either side of A band if movement toward center by both sides is not possible.
Materials and Methods: We have prepared a simulating model of sliding filament theory and observed mechanism of contraction on it.
Results: The sliding filament theory fails to explain the movement of Z discs when all sarcomeres in a myofibril are contracting simultaneously. Therefore, we proposed a new hypothesis that Z discs and actin filaments in the half part of each sarcomere, which is toward origin end of muscle fiber, are not pulled toward center of myosin filament instead myosin filament slide toward origin end, and in the other half of each sarcomere (which is toward insertion end) actin filaments slide over myosin filament toward origin end of the muscle.
Conclusion: This study adds a new insight into the sliding filament theory of muscle contraction and needs further confirmation on electron microscopic studies.
Sliding Filament Theory; Muscle Contraction; Actin; Myosin; Z Disc
| || |
|1. Huxley AF, Niedergerke R. Structural changes in muscle during contraction: interference microscopy of living muscle fibres. Nature. 1954;173:971-3. [DOI via Crossref] |
|2. Huxley HE, Hanson J. Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation. Nature. 1954;173:973-6. [DOI via Crossref] |
|3. Huxley AF. Prefatory chapter: muscle contraction. Annu Rev Physiol. 1988;50:1-16. [DOI via Crossref] [Pubmed] |
|4. Huxley AF. Muscular contraction. Review lecture given at the meeting of the Physiological Society at Leeds University on 14-15 December1973. J Physiol. 1974;243:1-43.|
|5. Madeleine A. Kirchberger. Excitation and contraction of skeletal muscle. In: John B. West (Ed.), Best & TaylorÂ’s Physiological Basis of Medical Practice. 12th edn. New York: Williams & Wilkins, 1990.pp. 62-103.|
|6. Ganong WF. Excitable tissue: muscle. In: Review of Medical Physiology. 22nd edn. McGraw Hill, 2007. pp. 65-84.|
|7. Guyton AC, Hall JE (Eds.). Contraction of skeletal muscle. In: Textbook of Medical Physiology. 11th edn. New York: Elsevier, 2007. pp. 72-84.|