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Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat

The extra heat liberation accompanying muscular shortening, the force-determined shortening heat, is defined as the difference between the heat produced when shortening occurs and that produced in an isometric contraction developing the same amount of force and performing the same amount of internal...

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Autores principales: Homsher, E., Mommaerts, W. F. H. M., Ricchiuti, N. V.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1973
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2226141/
https://www.ncbi.nlm.nih.gov/pubmed/4548714
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author Homsher, E.
Mommaerts, W. F. H. M.
Ricchiuti, N. V.
author_facet Homsher, E.
Mommaerts, W. F. H. M.
Ricchiuti, N. V.
author_sort Homsher, E.
collection PubMed
description The extra heat liberation accompanying muscular shortening, the force-determined shortening heat, is defined as the difference between the heat produced when shortening occurs and that produced in an isometric contraction developing the same amount of force and performing the same amount of internal work. Based on this definition, the initial energy production in twitches and tetanic contractions (E) is given by E = A + f (P, t) + α(F) x + W, where A is the activation heat, f(P, t), the tension-related heat (a heat production associated with the development and maintenance of tension), α(F)x, the force-determined shortening heat, and W, the external work. It is demonstrated that this equation accurately accounts for the time-course of heat evolution and the total initial energy production in both twitches and tetani at 0°C. The force-determined shortening heat is liberated, during shortening, in direct proportion to (a) the distance shortened, and (b) the force against which shortening occurs. The normalized value of the force-determined shortening heat coefficient, α(F)/P(o), is the same in both the twitch and the tetanus. Finally, this formulation of the muscle's energy production also accounts for the total energy production in afterload isotonic twitches at 20°C, where a Fenn effect is not demonstrable.
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spelling pubmed-22261412008-04-23 Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat Homsher, E. Mommaerts, W. F. H. M. Ricchiuti, N. V. J Gen Physiol Article The extra heat liberation accompanying muscular shortening, the force-determined shortening heat, is defined as the difference between the heat produced when shortening occurs and that produced in an isometric contraction developing the same amount of force and performing the same amount of internal work. Based on this definition, the initial energy production in twitches and tetanic contractions (E) is given by E = A + f (P, t) + α(F) x + W, where A is the activation heat, f(P, t), the tension-related heat (a heat production associated with the development and maintenance of tension), α(F)x, the force-determined shortening heat, and W, the external work. It is demonstrated that this equation accurately accounts for the time-course of heat evolution and the total initial energy production in both twitches and tetani at 0°C. The force-determined shortening heat is liberated, during shortening, in direct proportion to (a) the distance shortened, and (b) the force against which shortening occurs. The normalized value of the force-determined shortening heat coefficient, α(F)/P(o), is the same in both the twitch and the tetanus. Finally, this formulation of the muscle's energy production also accounts for the total energy production in afterload isotonic twitches at 20°C, where a Fenn effect is not demonstrable. The Rockefeller University Press 1973-12-01 /pmc/articles/PMC2226141/ /pubmed/4548714 Text en Copyright © 1973 by The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Homsher, E.
Mommaerts, W. F. H. M.
Ricchiuti, N. V.
Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat
title Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat
title_full Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat
title_fullStr Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat
title_full_unstemmed Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat
title_short Energetics of Shortening Muscles in Twitches and Tetanic Contractions : II. Force-Determined Shortening Heat
title_sort energetics of shortening muscles in twitches and tetanic contractions : ii. force-determined shortening heat
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2226141/
https://www.ncbi.nlm.nih.gov/pubmed/4548714
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