Modulation of passive force in single skeletal muscle fibres

Rassier, Dilson E.; Lee, Eun-Jeong; Herzog, Walter

doi:10.1098/rsbl.2005.0337

Cited by 37 publications

(30 citation statements)

References 20 publications

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“…The potential implication of titin in the force enhancement is on line with previous studies with single muscle fibers that showed an upward shift in the passive force-SL relation when cross-bridge formation was blocked and fibers were activated with increasing Ca 2ϩ concentration (27) or by electrical stimulation (39). These studies showed increases in forces between 5 and 15%, similar to the levels that we observed in sarcomeres in the current study.…”

Section: Discussionsupporting

confidence: 92%

Force produced by isolated sarcomeres and half-sarcomeres after an imposed stretch

Rassier

Pavlov

2012

American Journal of Physiology-Cell Physiology

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Rassier DE, Pavlov I. Force produced by isolated sarcomeres and half-sarcomeres after an imposed stretch. Am J Physiol Cell Physiol 302: C240 -C248, 2012. First published October 12, 2011 doi:10.1152/ajpcell.00208.2011.-When a stretch is imposed to activated muscles, there is a residual force enhancement that persists after the stretch; the force is higher than that produced during an isometric contraction in the corresponding length. The mechanisms behind the force enhancement remain elusive, and there is disagreement if it represents a sarcomeric property, or if it is associated with length nonuniformities among sarcomeres and half-sarcomeres. The purpose of this study was to investigate the effects of stretch on single sarcomeres and myofibrils with predetermined numbers of sarcomeres (n ϭ 2, 3. . . , 8) isolated from the rabbit psoas muscle. Sarcomeres were attached between two precalibrated microneedles for force measurements, and images of the preparations were projected onto a linear photodiode array for measurements of half-sarcomere length (SL). Fully activated sarcomeres were subjected to a stretch (5-10% of initial SL, at a speed of 0.3 m·s Ϫ1 ·SL Ϫ1 ) after which they were maintained isometric for at least 5 s before deactivation. Single sarcomeres showed two patterns: 31 sarcomeres showed a small level of force enhancement after stretch (10.46 Ϯ 0.78%), and 28 sarcomeres did not show force enhancement (Ϫ0.54 Ϯ 0.17%). In these preparations, there was not a strong correlation between the force enhancement and half-sarcomere length nonuniformities. When three or more sarcomeres arranged in series were stretched, force enhancement was always observed, and it increased linearly with the degree of half-sarcomere length nonuniformities. The results show that the residual force enhancement has two mechanisms: 1) stretch-induced changes in sarcomeric structure(s); we suggest that titin is responsible for this component, and 2) stretch-induced nonuniformities of halfsarcomere lengths, which significantly increases the level of force enhancement. myofibrils; myosin; titin; cross-bridges THE NOTION OF SARCOMERE LENGTH (SL) nonuniformity has played a significant role in the study of muscle contraction. It has been directly associated with several experimental observations, including the force "creep" observed at long muscle lengths (11,16), the relation between force and filament overlap (11,17,19), the kinetics of force development and relaxation (9, 43), and the effects of muscle stretch in force production (7,8,13,18,36,37). The latest is particularly important: when a stretch is applied to skeletal muscles during activation, force increases significantly while the energy consumption decreases (1, 30). The force remains elevated after the stretch to reach a steady-state level that is higher than that produced during isometric contractions at corresponding lengths (8,24,38). The mechanisms responsible for this "residual force enhancement" remain elusive and there is substantial disagreement in the literature...

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Section: Discussionsupporting

confidence: 92%

Force produced by isolated sarcomeres and half-sarcomeres after an imposed stretch

Rassier

Pavlov

2012

American Journal of Physiology-Cell Physiology

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“…Finally, a study performed with permeabilized fibres from mammalian muscles, in which extracellular structures and events associated with Ca 2þ release are not involved in stiffness or force measurements, confirmed the presence of the static tension, which was directly associated with the residual force enhancement [16]. In a few studies, the static tension is observed even a few seconds after activation stops [55,62,63], although the nature of this persistent passive force enhancement, is unknown, and it is not always observed.…”

Section: Mechanisms Of Force Enhancementmentioning

confidence: 79%

The mechanisms of the residual force enhancement after stretch of skeletal muscle: non-uniformity in half-sarcomeres and stiffness of titin

Rassier

2012

Proc. R. Soc. B.

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When activated skeletal muscles are stretched, the force increases significantly. After the stretch, the force decreases and reaches a steady-state level that is higher than the force produced at the corresponding length during purely isometric contractions. This phenomenon, referred to as residual force enhancement, has been observed for more than 50 years, but the mechanism remains elusive, generating considerable debate in the literature. This paper reviews studies performed with single muscle fibres, myofibrils and sarcomeres to investigate the mechanisms of the stretch-induced force enhancement. First, the paper summarizes the characteristics of force enhancement and early hypotheses associated with non-uniformity of sarcomere length. Then, it reviews new evidence suggesting that force enhancement can also be associated with sarcomeric structures. Finally, this paper proposes that force enhancement is caused by: (i) half-sarcomere non-uniformities that will affect the levels of passive forces and overlap between myosin and actin filaments, and (ii) a Ca 2þ -induced stiffness of titin molecules. These mechanisms are compatible with most observations in the literature, and can be tested directly with emerging technologies in the near future.

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“…Static stiffness is independent of stretching amplitude and velocity and dependent on sarcomere length. It has been hypothesized that static stiffness is due to a Ca 2+ -dependent stiffening of a non-crossbridge sarcomere structure, still unknown at present, which might be titin (Bagni et al, 1994(Bagni et al, , 2002(Bagni et al, , 2004Rassier et al, 2005;Roots et al, 2007;Colombini et al, 2009;Nishikawa et al, 2012;Nocella et al, 2012Nocella et al, , 2014Rassier, 2012).…”

Section: Introductionmentioning

confidence: 99%

Non-crossbridge stiffness in active muscle fibres

Colombini

Nocella

Bagni

2016

Journal of Experimental Biology

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Stretching of an activated skeletal muscle induces a transient tension increase followed by a period during which the tension remains elevated well above the isometric level at an almost constant value. This excess of tension in response to stretching has been called 'static tension' and attributed to an increase in fibre stiffness above the resting value, named 'static stiffness'. This observation was originally made, by our group, in frog intact muscle fibres and has been confirmed more recently, by us, in mammalian intact fibres. Following stimulation, fibre stiffness starts to increase during the latent period well before crossbridge force generation and it is present throughout the whole contraction in both single twitches and tetani. Static stiffness is dependent on sarcomere length in a different way from crossbridge force and is independent of stretching amplitude and velocity. Static stiffness follows a time course which is distinct from that of active force and very similar to the myoplasmic calcium concentration time course. We therefore hypothesize that static stiffness is due to a calcium-dependent stiffening of a noncrossbridge sarcomere structure, such as the titin filament. According to this hypothesis, titin, in addition to its well-recognized role in determining the muscle passive tension, could have a role during muscle activity.

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Modulation of passive force in single skeletal muscle fibres

Cited by 37 publications

References 20 publications

Force produced by isolated sarcomeres and half-sarcomeres after an imposed stretch

Force produced by isolated sarcomeres and half-sarcomeres after an imposed stretch

The mechanisms of the residual force enhancement after stretch of skeletal muscle: non-uniformity in half-sarcomeres and stiffness of titin

Non-crossbridge stiffness in active muscle fibres

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