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Effects of submaximal activation on the determinants of power of chemically skinned rat soleus fibres

Gilliver, Sally F und Degens, Hans und Jones, David A und Rittweger, Joern (2011) Effects of submaximal activation on the determinants of power of chemically skinned rat soleus fibres. Experimental Physiology, 96 (2), Seiten 171-178. ISSN 0958-0670.

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Kurzfassung

Reducing the activating calcium concentration with skinned fibres is known to decrease isometric force and maximal shortening velocity, both of which will reduce the peak power. However, power is also a function of the curvature of the force-velocity relationship, and there is limited information on how changes in activating calcium affect this important property of muscle fibres. Force-velocity relationships of permeabilized single type I fibres from rat soleus muscle were determined using isotonic contractions at 15°C with both maximal (pCa 4.5) and submaximal activation (pCa 5.6). The rate of tension redevelopment (k(tr)), which provides a measure of sum of the apparent rate constants for cross-bridge attachment and detachment (f(app) + g(app)) following a rapid release and restretch, was also measured. Compared with pCa 4.5, specific tension (P(o)) at pCa 5.6 declined by 22 ± 8% (mean ± s.d.) and the maximal velocity of shortening (V(max)) fell by 44 ± 7%, but curvature of the force-velocity relationship (a/P(o)) rose by 47 ± 31%, indicating a less concave relationship. The value of k(tr) declined by 23 ± 7%. The change in a/P(o) reduced the impact of changes in P(o) and V(max) on peak power by approximately 25%. Fitting the data to Huxley's model of cross-bridge action suggests that lower activating calcium decreased both the rate constant for cross-bridge attachment (f) and that for detachment of negatively strained cross-bridges (g(2)). The fact that V(max) (and thus g(2)) changed to a greater extent than k(tr) (f(app) + g(app)) is the reason that reduced activation results in a reduction in curvature of the force-velocity relationship.

Dokumentart:Zeitschriftenbeitrag
Titel:Effects of submaximal activation on the determinants of power of chemically skinned rat soleus fibres
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Gilliver, Sally FManchester Metropolitan University
Degens, HansManchester Metropolitan University
Jones, David AManchester Metropolitan University
Rittweger, Joernjoern.rittweger@dlr.de
Datum:Februar 2011
Erschienen in:Experimental Physiology
Referierte Publikation:Ja
In SCOPUS:Ja
In ISI Web of Science:Ja
Band:96
Seitenbereich:Seiten 171-178
ISSN:0958-0670
Status:veröffentlicht
Stichwörter:Skeletal muscle; skinned fibres; power; force-velocity relationship
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W FR - Forschung unter Weltraumbedingungen (alt)
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W FR - Forschung unter Weltraumbedingungen
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Integrative Studien (alt)
Standort: Köln-Porz
Institute & Einrichtungen:Institut für Luft- und Raumfahrtmedizin > Weltraumphysiologie
Hinterlegt von: Jörn Rittweger
Hinterlegt am:09 Feb 2011 10:39
Letzte Änderung:12 Dez 2013 21:14

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