Fluctuations in tension during contraction of single muscle fibers

Julian Borejdo, M. F. Morales

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26 Citations (Scopus)

Abstract

We have searched for fluctuations in the steady-state tension developed by stimulated single muscle fibers. Such tension "noise" is expected to be present as a result of the statistical fluctuations in the number and/or state of myosin cross-bridges interacting with thin filament sites at any time. A sensitive electro-optical tension transducer capable of resolving the expected fluctuations in magnitude and frequency was constructed to search for the fluctuations. The noise was analyzed by computing the power spectra and amplitude of stochastic fluctuations in the photomultiplier counting rate, which was made proportional to muscle force. The optical system and electronic instrumentation together with the minicomputer software are described. Tensions were measured in single skinned glycerinated rabbit psoas muscle fibers in rigor and during contraction and relaxation. The results indicate the presence of fluctuations in contracting muscles and a complete absence of tension noise in eith rigor or relaxation. Also, a numerical method was developed to simulate the power spectra and amplitude of fluctuations, given the rate constants for association and dissociation of the cross-bridges and actin. The simulated power spectra and the frequency distributions observed experimentally are similar.

Original languageEnglish
Pages (from-to)315-334
Number of pages20
JournalBiophysical Journal
Volume20
Issue number3
DOIs
StatePublished - 1 Jan 1977

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Muscle Contraction
Noise
Muscles
Minicomputers
Psoas Muscles
Optical Devices
Myosins
Transducers
Actins
Software
Rabbits

Cite this

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Fluctuations in tension during contraction of single muscle fibers. / Borejdo, Julian; Morales, M. F.

In: Biophysical Journal, Vol. 20, No. 3, 01.01.1977, p. 315-334.

Research output: Contribution to journalArticleResearchpeer-review

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AU - Borejdo, Julian

AU - Morales, M. F.

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