Muscle as a Metamaterial Operating Near a Critical Point

Caruel, Matthieu; Allain, Jean-Marc; Truskinovsky, Lev

doi:10.1103/physrevlett.110.248103

Cited by 65 publications

(114 citation statements)

References 54 publications

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“…The obtained estimate (A = 0.5, D = 0.01) suggests that muscle myosins, operating in stall conditions (isometric contractions), are in phase III. The proposed representation of the ATP hydrolysis (through parameter A) explains stabilization of the power stroke mechanism in skeletal muscles in the negative stiffness regime [7] and may be also behind titin based force generating mechanism at long sarcomere lengths that does not rely on actin-myosin based cross-bridge interactions [42].…”

Section: Fig 4 (A)mentioning

confidence: 99%

“…In view of this analogy, detailed in [28], it is instructive to estimate the four non-dimensional parameters of the model by using the available data on molecular motors operating in muscle cells. We choose the time scale to be τ = η/k 0 ∼ 0.1 ms where η ∼ 0.38 ms. pN/nm is the viscosity adopted in [7] and k 0 ∼ 3 pN/nm is the stiffness of the cross-bridge in pre and post power stroke configurations. The spatial scale is l = a ∼ 10nm, the characteristic size of a motor power-stroke [40] and the stress scale is k = k 0 .…”

Section: Fig 4 (A)mentioning

confidence: 99%

“…Thus, molecular motors can either stiffen the cytoskeleton through actively generated pre-stress [2] or fluidize it by facilitating remodeling [3]. Powered by ATP hydrolysis, living systems can also operate in mechanical regimes with negative passive stiffness as in the case of hair cells [4,5] and muscle halfsarcomeres [6,7]. In those cases metabolic resources are used to modify the mechanical susceptibility of the system and stabilize the apparently unstable states [8][9][10].…”

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Rigidity generation by nonthermal fluctuations

2016

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Active stabilization in systems with zero or negative stiffness is an essential element of a wide variety of biological processes. We study a prototypical example of this phenomenon at a microscale and show how active rigidity, interpreted as a formation of a pseudo-well in the effective energy landscape, can be generated in an overdamped ratchet-type stochastic system. We link the transition from negative to positive rigidity with correlations in the noise and show that subtle differences in out-of-equilibrium driving may compromise the emergence of a pseudo-well. The response of a living system to mechanical loading depends not only on the properties of the constituents and their connectivity, but also on the presence of nonthermal endogenous driving [1]. Thus, molecular motors can either stiffen the cytoskeleton through actively generated pre-stress [2] or fluidize it by facilitating remodeling [3]. Powered by ATP hydrolysis, living systems can also operate in mechanical regimes with negative passive stiffness as in the case of hair cells [4,5] and muscle halfsarcomeres [6,7]. In those cases metabolic resources are used to modify the mechanical susceptibility of the system and stabilize the apparently unstable states [8][9][10].At the structural level, active rigidity may be the outcome of tensegrity tightening [11], connectivity change [12], steric interactions [13], or the prestress exploiting strong nonlinearity of the passive response [14,15]. ATP induced stiffening can even take place at the level of individual structural elements as in the case of the Frank-Starling effect in cardiac muscles that cannot be explained by a simple filament overlap change [16].In this Letter we show that active rigidity can also emerge at the micro-scale level through resonant nonthermal excitation of molecular degrees of freedom as in the case of an inverted pendulum [17]. Following this inertial prototype, we construct an example of a mechanically unstable overdamped system where stabilization and creation of a new pseudo-well in the effective energy landscape can be induced by a colored noise. The proposed mechanism of rigidity generation requires a finite distance from equilibrium and is therefore different from the more conventional entropic stabilization [18]. The possibility of actively tunable rigidity opens interesting prospects not only in biomechanics [19] but also in engineering design incorporating negative stiffness [20] or aiming at synthetic materials stabilized dynamically [21,22].We illustrate our idea on a simple bi-stable mechanical system described by a single collective variable: the negative stiffness is viewed as a result of coarse-graining in a microscopic system with domineering long range interactions [23]. We assume that this 'snap-spring' is exposed to both thermal and correlated noises and acts against a linear spring which qualifies it as a molecular motor operating in stall conditions [24]. Instead of the conventional focus on active force, we study in this Letter a possibility of generating ...

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confidence: 99%

Section: Fig 4 (A)mentioning

confidence: 99%

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Rigidity generation by nonthermal fluctuations

2016

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“…[121]. The concept of operating a stabilized mechanical system close to a critical point had also been found in biological systems such as myofibrils [122], muscles [123], and hair cell walls [124], where-among others-the high, controllable sensitivity near the critical point is exploited.…”

Section: Springs As Structural Analogsmentioning

confidence: 99%

Exploiting Microstructural Instabilities in Solids and Structures: From Metamaterials to Structural Transitions

Kochmann

Bertoldi

2017

Applied Mechanics Reviews

196

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Instabilities in solids and structures are ubiquitous across all length and time scales, and engineering design principles have commonly aimed at preventing instability. However, over the past two decades, engineering mechanics has undergone a paradigm shift, away from avoiding instability and toward taking advantage thereof. At the core of all instabilities-both at the microstructural scale in materials and at the macroscopic, structural level-lies a nonconvex potential energy landscape which is responsible, e.g., for phase transitions and domain switching, localization, pattern formation, or structural buckling and snapping. Deliberately driving a system close to, into, and beyond the unstable regime has been exploited to create new materials systems with superior, interesting, or extreme physical properties. Here, we review the state-of-the-art in utilizing mechanical instabilities in solids and structures at the microstructural level in order to control macroscopic (meta)material performance. After a brief theoretical review, we discuss examples of utilizing material instabilities (from phase transitions and ferroelectric switching to extreme composites) as well as examples of exploiting structural instabilities in acoustic and mechanical metamaterials.

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“…The main functionality of the powerstroke mechanism is attributed in this approach to fast passive force recovery. The power stroke then plays the role of a passive folding-unfolding mechanism which can be activated by loading but is not directly ATP driven [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Power-stroke-driven actomyosin contractility

Sheshka

Truskinovsky

2014

Phys. Rev. E

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In ratchet-based models describing actomyosin contraction the activity is usually associated with actin binding potential while the power-stroke mechanism, residing inside myosin heads, is viewed as passive. To show that contraction can be propelled directly through a conformational change, we propose an alternative model where the power stroke is the only active mechanism. The asymmetry, ensuring directional motion, resides in steric interaction between the externally driven power-stroke element and the passive nonpolar actin filament. The proposed model can reproduce all four discrete states of the minimal actomyosin catalytic cycle even though it is formulated in terms of continuous Langevin dynamics. We build a conceptual bridge between processive and nonprocessive molecular motors by demonstrating that not only the former but also the latter can use structural transformation as the main driving force.

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Muscle as a Metamaterial Operating Near a Critical Point

Cited by 65 publications

References 54 publications

Rigidity generation by nonthermal fluctuations

Rigidity generation by nonthermal fluctuations

Exploiting Microstructural Instabilities in Solids and Structures: From Metamaterials to Structural Transitions

Power-stroke-driven actomyosin contractility

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