Ebook Muscle contraction and cell motility: Part 2

(BQ) Part 2 book “Muscle contraction and cell motility” has contents: Stiffness of contracting human muscle measured with supersonic shear imaging, essential myosin light chains regulate myosin function and muscle contraction, the catch state of molluscan smooth muscle,… and other contents.

Chapter Stiffness of Contracting Human Muscle Measured with Supersonic Shear Imaging Kazushige Sasakia and Naokata Ishiib aFaculty of Human Sciences and Design, Japan Women’s University, Tokyo 112-8681, Japan bDepartment of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan sasakik@fc.jwu.ac.jp, ishii@idaten.c.u-tokyo.ac.jp Recently, an ultrasound-based elastographic technique called supersonic shear imaging (SSI) has been developed and used to measure stiffness (shear modulus) of in vivo muscles This review describes the theoretical background of SSI, summarizes some basic observations on the shear modulus of contracting human muscles, and presents the latest experimental findings It is well documented that the muscle shear modulus increases with increasing intensity of contraction A linear association has been found between the muscle shear modulus and motor unit activity assessed with surface electromyography Moreover, we have demonstrated both the length-dependent changes in shear Muscle Contraction and Cell Motility: Fundamentals and Developments Edited by Haruo Sugi Copyright © 2017 Pan Stanford Publishing Pte Ltd ISBN  978-981-4745-16-1 (Hardcover),  978-981-4745-17-8 (eBook) www.panstanford.com 210 Stiffness of Contracting Human Muscle Measured with Supersonic Shear Imaging modulus and the association of shear modulus with contractile force, even when the motor unit activity is controlled by direct electric stimulation of muscle These findings provide strong evidence that the muscle shear modulus measured with SSI can be a useful indicator of muscle activation level or contractile force in a variety of conditions While the structures and mechanisms determining muscle stiffness in vivo are not fully understood, the result of our pilot study suggests that the shear modulus of contracting muscle may reflect both the single-fiber stiffness (cross-bridge kinetics) and the motor unit recruitment, i.e., the number of activated muscle fibers 8.1  Introduction In studies of muscle mechanics, stiffness of contracting single fibers has been used as a measure of the number of attached cross-bridges at any instance It has usually been quantified by measuring force responses to small (Po (adapted from Tsuchiya et al., 1979) Measuring stiffness of contracting human muscles in vivo is also of great physiological significance, because it may provide us with information about the force-generating capacity of muscle fibers, which is determined by the relation between sarcomere length and contractile force (length–force relation) The length–force characteristics of muscle can be estimated in vivo by measuring maximal voluntary torques at varied joint angles However, obtained relation between joint torque and joint angle may be considerably truncated from the original length–force relation of muscle, due mainly to changes in effective moment- Methods and Materials arm length with joint angles (Maganaris, 2001; Sasaki et al., 2014) It can also be influenced by activation of synergistic and antagonistic muscle groups Therefore, direct determination of the relation between muscle length and stiffness (length–stiffness relation) is regarded as highly effective to predict the length– force relations of a variety of muscles in the body, even without measurements of joint torques However, application of length oscillation with small amplitude and high frequency to muscles in vivo is substantially impossible, due to the presence of a large amount of series elasticity and intervening soft tissues A recently developed ultrasound-based elastographic technique, “supersonic shear imaging” (SSI; Bercoff et al., 2004) can overcome this problem and potentially be useful for in vivo measurements of stiffness in contracting muscle Also, in place of its poor time resolution due to complicated image processing, SSI can visualize changes in regional stiffness within muscle during steady-state contractions Among other things, it may provide us with an insight into the localization of recruited fibers or motor units in a variety of conditions, e.g., in contractions at varied voluntary activation level, during sustained exertion of small contractile force, during the course of muscle fatigue, etc This review lists some recent studies on stiffness of contracting human muscles, with special reference to the effects of muscle activation level, muscle length, and contraction types 8.2  Methods and Materials 8.2.1  Theoretical Basis of Supersonic Shear Imaging SSI is based on the B-mode ultrasound imaging that has widely been used in research and clinical diagnosis In addition to usual scanning supersonic waves for image acquisition, SSI projects another strong supersonic beam that is focused on and hits given portions within a tissue subjected to observation There, it gives rise to a shear deformation that then propagates three dimensionally as shear wave In a linearly elastic and transversely isotropic material, its shear elastic modulus (G) is a function of the propagation velocity of shear wave (Vs) as described by the following equation: 213 214 Stiffness of Contracting Human Muscle Measured with Supersonic Shear Imaging G = rVs2, (8.1) G = E/2(1 + ν), (8.2) where r is the density of muscle (generally assumed to be 1,000 kg/m3) Therefore, regional stiffness can be estimated by processing the reflected ultrasound signals and measuring the propagation velocity of shear waves When muscle is subjected to measurements, shear deformations produced at given portions of muscle fibers can also propagate three dimensionally Thus, observations of longitudinal plane should provide regional shear elastic modulus along the fiber axis In general, shear elastic modulus (G) of a rod-shaped cantilever is proportional to Young’s modulus (E) as described by the following equation: where ν is the Poisson ratio Therefore, measured value of shear elasticity presumably represents Young’s modulus averaged for muscle fibers included in the region of interest Standing on the above theoretical basis, the SSI scanner (Aixplorer, SuperSonic Imagine, France) implements an ultrafast (up to 20 kHz) echographic imaging of the shear wave propagation to calculate the shear wave velocity along the principal axis of ultrasound probe in less than 20 ms (Bercoff et al., 2004; Hug et al., 2015) Such a short acquisition time minimizes the influence of any motion artifacts (Gennisson et al., 2010) At present, the short acquisition time is a critical advantage of SSI over the other techniques such as magnetic resonance elastography Although magnetic resonance elastography can provide three-dimensional shear elasticity map with an excellent spatial resolution, the long acquisition time (several minutes even for two-dimensional measurements) (Bensamoun et al., 2008) limits its application to relatively static organs/conditions Therefore, SSI opens a new possibility for assessing elastic properties of in vivo human muscles during forceful but brief contractions Moreover, the SSI scanner is portable and requires no external vibrator, so that the measurement can be free from various experimental constraints In 2010, some researchers presented preliminary data on the stiffness of in vivo human muscles determined by SSI (Gennisson et al., 2010; Nordez and Hug, 2010; Shinohara et al., Methods and Materials 2010) Since then, this technique has drawn increasing attention in the field of human skeletal muscle physiology and biomechanics 8.2.2  Some Technical Issues Typical examples of shear elasticity imaging using SSI are shown in Fig 8.4 The muscle shear modulus obtained with a resolution of × mm is spatially filtered and color-coded, comprising a two-dimensional map superimposed on a B-mode ultrasound image To obtain a representative value, the shear modulus is generally averaged over a selected region of interest (ROI) using bundled software of the SSI scanner or custom-designed computer program (Bouillard et al., 2011, 2012a) (a) (b) (c) Figure 8.4 Examples of shear modulus distribution superimposed on longitudinal ultrasound image of the biceps brachii muscle at rest (a) and during contractions at 10% (b) and 40% (c) of maximal voluntary contraction The shear modulus typically increases with increasing contraction intensity While it has been well demonstrated that the shear modulus measurement using SSI is highly accurate and reliable (Bouillard et al., 2011; Eby et al., 2013; Koo et al., 2013; Lacourpaille 215 216 Stiffness of Contracting Human Muscle Measured with Supersonic Shear Imaging et al., 2012; Yoshitake et al., 2014), there are some technical issues that require careful consideration First, the upper limit of shear elasticity measurement is currently 266.6 kPa (equivalent shear wave velocity of 16.3 m/s) Despite large inter-muscle and inter-individual differences (Sasaki et al., 2014), this limit is generally insufficient for assessing the muscle shear modulus during maximal contractions Second, a time resolution of Hz in the current SSI scanner precludes researchers from studying the muscle stiffness changes during ballistic (quick and explosive) contractions or fast movements A recent study, however, suggests that the above two limitations can be overcome by both hardware and software improvements in the near future (Ateş et al., 2015) Third, the orientation of ultrasound probe greatly influences the measured shear modulus, because skeletal muscle is composed of muscle fiber bundles (fascicles) and anisotropic in structure In fact, Gennisson et al (2010) showed that in the human biceps brachii muscle, the shear wave velocity was highest when propagating along the muscle fascicles, and decreased with increasing the probe angle relative to the fascicles This finding suggests that the ultrasound probe should be placed parallel to the fascicles for the accurate measurement of muscle shear modulus The dependence of shear wave velocity on the probe orientation also implies that the shear modulus can be underestimated in pennate (pinnate) muscles, i.e., muscles with oblique orientation of fascicles relative to the longitudinal axis of whole muscle, though a recent study (Miyamoto et al., 2015) on resting human muscles suggests that the magnitude of underestimation is negligibly small if the pennation angle is less than 20° Finally, the measured shear modulus is more or less associated with the clarity of ultrasound image, so that the accuracy and reliability of measurement are influenced by the skill and experience of operator (Hug et al., 2015) 8.3  Muscle Activation Level and Stiffness 8.3.1  Association of Shear Modulus with Joint Torque A simple and practical way of associating muscle stiffness with activation level is to examine the shear modulus at several different contraction intensities In general, contraction intensity Muscle Activation Level and Stiffness is defined as a contraction-induced muscle force generation relative to that during maximal voluntary contraction (MVC) Because of the difficulty to directly measure individual muscle force in vivo, most of the studies on human muscles use the torque around the relevant joint axis (joint torque) as a global measure of muscle force generation Nordez and Hug (2010) investigated the shear modulus of the human biceps brachii muscle and its association with elbow flexion torque using SSI Although they employed only low contraction intensities (ramp contraction of up to 30%MVC) because of the limited range (0–100 kPa) of shear modulus measurement in the earlier version of SSI scanner, a curvilinear relation between the shear modulus and contraction intensity was observed Namely, they reported a relatively sharp increase in shear modulus preceded by little change at very low contraction intensities The same group of authors subsequently performed another experiment (Bouillard et al., 2012b) in which the shear modulus was measured in elbow flexor synergists (the short and long heads of biceps brachii, brachialis, and brachioradialis muscles) The result indicated that the non-linear shear modulus–torque relation of the biceps brachii muscle (Nordez and Hug, 2010) could be explained by the change in relative contribution of elbow flexor synergists to joint torque as a function of contraction intensity By contrast, Yoshitake et al (2014) studied the biceps brachii muscle with a broader range of contraction intensities (up to 60%MVC) and found a linear association of the shear modulus with elbow flexion torque A linear association of the biceps brachii stiffness and elbow flexion torque was also demonstrated by Dresner et al (2001) using magnetic resonance elastography Bouillard et al (2011, 2012a) have studied the association of shear modulus with joint torque in human finger muscles (the first dorsal interosseous and the abductor digiti minimi) During isometric ramp contractions with linearly increasing joint torque, the shear modulus increased linearly in both muscles As these muscles are considered the single agonist for abduction of index finger and little finger, respectively, the individual muscle force can be directly inferred from the measurement of joint torque, assuming a negligible change in moment arm during contraction (Hug et al., 2015) Therefore, these results 217 218 Stiffness of Contracting Human Muscle Measured with Supersonic Shear Imaging provide evidence that the shear modulus determined by SSI is a measure of contractile force produced by the muscle of interest 8.3.2  Association of Shear Modulus with Motor Unit Activity Since the shear modulus determined by SSI represents a regional stiffness of target tissue, it is likely that the muscle shear modulus is related more to motor unit activity within a single muscle rather than to joint torque that represents a net effect of all synergistic and antagonistic muscles crossing the joint In fact, several studies have investigated the association of muscle shear modulus with motor unit activity in addition to joint torque In human muscle studies, motor unit activity is commonly examined by surface electromyography (EMG) With regard to the relation between EMG and muscle mechanical activity, it has been frequently observed that surface EMG amplitude in large limb muscles increases non-linearly with joint torque (Bouillard et al., 2012b; Lawrence and De Luca, 1983; Nordez and Hug, 2010; Sasaki and Ishii, 2005; Watanabe and Akima, 2009) Several physiological and technical reasons may account for the non-linearity, including motor unit recruitment strategy (Fuglevand et al., 1993; Lawrence and De Luca, 1983), inhomogeneous muscle activity (van Zuylen et al., 1988), mixed muscle fiber composition (Woods and Bigland-Ritchie, 1983), and amplitude cancellation (Keenan et al., 2005) Apart from these explanations, the above-mentioned study (Bouillard et al., 2012b) on the shear modulus of human elbow flexor muscle synergists raised an intriguing possibility that the changes in load sharing, i.e., relative contribution to joint torque, between synergists partly explain the non-linear EMG–torque relation of the biceps brachii muscle In fact, several studies have consistently shown that the shear modulus can be linearly related to EMG amplitude in the biceps brachii muscle (Lapole et al., 2015; Nordez and Hug, 2010; Yoshitake et al., 2014) The linear association also holds true for other muscles including small hand muscles where both shear modulus and EMG are linearly related to joint torque (Bouillard et al., 2011, 2012a) 440 Role of Dynamic and Cooperative Conformational Changes in Actin Filaments Noguchi TQP, Komori T, Umeki N, Demizu N, Ito K, Iwane AH, Tokuraku K, Yanagida T, Uyeda TQP (2012) G146V mutation at the hinge region of actin reveals a myosin class-specific requirement of actin conformations for motility J Biol Chem, 287: 24339–24345 Noguchi TQP, Morimatsu 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52(Supplement 1): S113 Uyeda TQP, Abramson PD, Spudich JA (1996) The neck region of the myosin motor domain acts as a lever arm to generate movement Proc Natl Acad Sci U S A, 93: 4459–4464 Uyeda TQP, Iwadate Y, Umeki N, Nagasaki A, Yumura S (2011) Stretching actin filaments within cells enhances their affinity for the myosin II motor domain PLoS One, 6: e26200 van den Ent F, Amos LA, Löwe J (2001) Prokaryotic origin of the actin cytoskeleton Nature, 413: 39–44 Verkhovsky AB, Svitkina TM, Borisy GG (1999) Self-polarization and directional motility of cytoplasm Curr Biol, 9: 11–20 References von der Ecken J, Muller M, Lehman W, Manstein DJ, Penczek PA, Raunser S (2015) Structure of the F-actin-tropomyosin complex Nature, 519: 114–117 Wakabayashi K, Sugimoto Y, Tanaka H, Ueno Y, Takezawa Y, Amemiya Y (1994) X-ray diffraction evidence for the extensibility of actin and myosin filaments during muscle contraction Biophys J, 67: 2422–2435 Wang YL (1985) Exchange of actin subunits at the leading edge of living fibroblasts: Possible role of treadmilling J Cell Biol, 101: 597–602 Wiggan O, Shaw AE, DeLuca JG, Bamburg JR (2012) ADF/cofilin regulates actomyosin assembly through competitive inhibition of myosin II binding to F-actin Dev Cell, 22: 530–543 Yumura S, Itoh G, Kikuta Y, Kikuchi T, Kitanishi-Yumura T, Tsujioka M (2013) Cell-scale dynamic recycling and cortical flow of the actin-myosin cytoskeleton for rapid cell migration Biol Open, 2: 200–209 443 Index ABP, see actin-binding protein ABP molecules 427–428 ABRM, see anterior byssus retractor muscle acetylcholine 343, 345, 352, 357 actin archaeal 431–432 bacterial 417, 431 cytoplasmic 416–417 eukaryotic 416–417, 431–432 mutant 432–433 regulated 285 yeast 416 actin binding 7, 41, 91–92, 101, 131, 283 actin-binding protein (ABP) 415–419, 421, 423–425, 427–428, 430 actin-binding sites 89, 91, 118, 121, 135–136, 275 actin cables 125–127 actin concentration 122, 283 actin cytoskeleton 387, 399–400 actin filament conformation 419 actin filament sliding 121, 123–124, 131, 139, 200 actin filament sliding velocity 123, 131, 139, 291 actin filaments 3–8, 17–18, 20–23, 31–32, 36–40, 45–47, 53, 61, 119–125, 131, 135–137, 280, 349–350, 353–355, 415–435 anti-parallel 37 mutant 433 myosin II S1-bound 429 nascent 419 stretched 405, 429–430 in vitro sliding velocity of 274, 281 actin functions 415–417, 431 actin gene 431, 433 actin meshwork 390, 396 actin molecule 417–418, 432–433 globular 6, 42 actin monomers 8, 38, 40, 392 actin-myosin crossbridges 432 actin polymerization rate 393 actin protomers 416, 418, 420–421, 424, 427–428, 430–434 cooperative conformational changes of 434 actin retrograde flow (ARF) 392–394, 396 actin strands 84, 389 actin subunits 46–47 actin-titin interaction 182 actin–myosin interaction 93, 96, 99–101, 119 cyclic 122, 136, 139 actin–myosin preparation 91 actin–myosin sliding 124, 126–127, 133 actin–myosin sliding velocity 126 446 Index activated muscle contraction 133 active muscle 41, 49, 51, 53, 55, 60, 64, 67, 143–144, 149, 152, 161, 169, 265 active muscle tension 148 active tension 156, 160, 173, 176–181, 183, 211 low 174, 181 actomyosin 122, 254, 389, 396, 398 actomyosin contraction 387, 392, 395–396, 399, 404 actomyosin interactions 89, 198 amino acids 87, 274–276, 288, 312, 347 anterior byssus retractor muscle (ABRM) 344 antibodies 12–14, 20–21, 23, 25–31, 91–92, 117–119, 129–131, 133, 135–136, 139 anti-CAD 12, 20, 131–132, 136 polyclonal 138 site-directed 12 ARF, see actin retrograde flow ATP consumption 90, 100, 254, 260, 262–263, 344 ATP-dependent actin–myosin sliding 123–125 ATP hydrolisis 15, 17, 19, 21 ATP hydrolysis 4, 7–8, 83, 99, 121–122, 125, 151, 156, 161, 253–254, 265, 306, 350, 419 ATP hydrolysis in living myosin filaments 15 ATP-induced myosin head movement 16–22, 129 reversibility of 20 ATP-induced myosin head power stroke 22, 25, 27–30 ATP utilization in cardiac muscle 260–261 ATPase 83, 89–93, 98, 135, 254–255, 275, 307 ATPase activity 38–39, 91–92, 98–100, 136 actin-activated 137, 355 actin-activated myosin 274, 281–282, 284 steady-state 122–123 ATPase cycle 40, 143–144, 160, 354, 434 acto-myosin 155, 161 atrium 286, 305, 315, 317 axoneme 373, 375–377, 379–380, 382–383 elastase-treated 382–384 biceps brachii muscle 215, 217–218, 223–224 human 216–217 biochemical assays 353–355 biphasic tension 152 bipolar myosinmyosin rod cofilaments 14 blebbistatin 197–199, 352, 358 bony fish muscles 64–65 Bragg’s law 44–47 bridge muscle physiology 119 C-protein 40–41, 60, 82 Ca2+/calmodulin-dependent protein kinase II (CAMKII) 304–305, 307 calcium upregulation 310 Index calcium uptake 303–304, 306, 308, 310, 312, 314, 316, 318, 320 CAMKII, see Ca2+/calmodulindependent protein kinase II cardiac dysfunction 303, 309, 318–319 cardiac function 291, 304, 306, 309, 311, 320 cardiac muscle 198, 201, 249–250, 252, 254, 256, 258, 260–262, 264, 266, 282, 313, 316–319 cardiac muscle contractility 304 cardiomyocytes 252–253, 262, 273, 303, 311 cardiomyopathy 303, 308–309, 314 dilated 308–309 catch, mechanism of 344 catch muscle 343, 346 cell migration 335, 387–388, 390, 392, 394–396, 398–406 biomechanics of 387–388, 390, 392, 394, 396, 398, 400, 402, 404, 406 cells bacterial 431 non-muscle 310, 416, 419 central-pair microtubules 372–373, 380, 384 cerebral vasospasm 334–335 chemotaxis 405 cholesterol 333–334, 337–339 cilia 372, 380, 388, 392 cofilin 387, 393, 400–401, 405, 420–426, 428–429, 433 connective tissues 172, 180, 226, 228, 261 contractile cycle 55, 59, 64 contractile filaments 85, 198 contractile proteins 119, 235, 244 contracting muscle 8, 35, 67, 95, 101, 125, 139, 210, 213, 226, 250 contracting muscle cell 253 contracting muscle fibers 24, 32, 127, 221, 225 contraction active 148, 358–359 eccentric 251 independent 334 lengthening 223–226 maximal voluntary 215, 217, 222, 224 steady-state 210, 213 cooperative conformational change 420, 423–424, 428, 435 crawling cell migration 387, 389, 404–405 crawling cells 399–400, 402, 404 crawling migration 387–389, 394, 396, 401, 404 cross-bridges 21, 89, 96, 195, 202, 210, 226, 284, 287 cross-striations 4–5 crossbridge action 185 crossbridge attachment 261 crossbridge cycle 55, 58, 151–152, 155, 252 crossbridge cycling 253, 262 cytoskeleton 85, 389, 391, 393, 395, 398 cytosol 304–305, 336–337 Dictyostelium 282, 388, 390, 394, 397–398, 401–402, 404–405, 429 447 448 Index diffraction 42–48, 59 basic concepts 42–43, 45, 47 doublet microtubules 371–373, 376–379, 382–384 drebrin 423–425 dynamic contractile unit 97, 99, 101 dynamic contractions 223, 225, 227 dynein 371–373, 375–379, 383–384, 390 dynein activity 371–372, 374, 376–378, 380–384 regulation of 381–383 dynein arms 371–373, 376–381, 383–384 elastic modulus 213–214 elasticity 96, 147–148, 210, 213 electron microscopy 40–41, 51, 77 environmental chamber experiments 18, 23, 28, 30–32 equatorial intensity profile 48–49 equatorial reflections 48–49, 51, 53, 55, 57 essential myosin light chains 276 F-actin 200, 389–390, 392–393, 397, 399, 401, 405 tension of 399, 401 F-actin bundles 390, 400 F-actin network 393–394 F-actin-tropomyosin 285 familial hypertrophic cardiomyopathy 262, 274, 289 familial hypertrophic cardiomyopathy (FHC) 262, 274, 289–291 fatigue 161, 235–244 neuromuscular 219 FDB, see flexor digitorum brevis Fenn effect 89, 249, 251, 262–265 FHC, see familial hypertrophic cardiomyopathy fibroblasts 388, 390–391, 394, 396–401, 403–404 fish keratocytes 430 fish muscle 47–48, 56, 64, 66 flagella 371–374, 376, 380–382, 388 flagellar oscillation 372–375, 383–384 flexor digitorum brevis (FDB) 172, 186, 237 Force Potentiation 169–170, 172, 174, 176, 178, 180, 182, 184, 186 Fourier synthesis 49–53 gold particles 14–15, 17–19, 23, 26–27, 30 heart 90, 259, 265, 274, 276, 284, 286–287, 290, 303–304, 306–310, 312–316, 318–320 heart failure, animal models of 304, 309, 311 Index heart muscle 86, 101 human muscles 144, 209, 212–214, 216, 219 hydrated myosin filaments 16, 22, 31, 129 hypertrophic cardiomyopathy 286, 289 inorganic phosphate 144, 151, 158, 250, 259–261 insect flight muscle 64, 66–67 interfilamentary distance 182 isoforms fast-twitch skeletal muscle 306 slow-twitch skeletal muscle 306 isometric contraction 90, 150, 197, 210, 224–226, 250, 253–254, 262 isometric muscle 143, 147, 149, 152–154, 159 isometric tension 94, 133, 135, 151, 169, 174–175, 261, 265 isometric value 263–264 keratocytes 393, 398–399 kinases 86, 313, 316, 346–347, 357 kinetic modelling 158 length–force relation 212, 221–222 length–shear modulus relation 221–223 lever arm 31, 40–41, 59, 62, 118, 172, 237, 275, 278–279, 281–282, 284, 287–288, 434 helical 275, 278, 281 lever arm domain 91, 129, 432 lever arm mechanism 136, 138 light chains 40–41, 82–83, 129–130, 133 alkali 275–276 regulatory myosin 347, 355 ventricular myosin 276 light meromyosin 5, 82, 119, 275, 347 mammalian muscle 144, 160, 353 active 144, 147–148 mammalian non-muscle cells 416 maximal voluntary contraction (MVC) 215, 217, 219, 222–225 membrane lipid rafts 333–334, 337–338 meridional reflections 59, 61, 63 meromyosin, heavy 5, 82, 119 mesenchymal stem cells 403 MgADP 147, 151–152, 155–156 MgATPase activity 25, 118, 135, 137–138 MHC, see myosin heavy chain MHC isoform 261–262 microtubule sliding 372, 375–377, 379–382 microtubules 377, 379–380, 383, 389, 395–396 central pair 377, 382–384 MLC, see myosin light chain MLCK, see myosin light chain kinase molecular clutches 393–394, 396 449 450 Index molluscan 346 molluscan smooth muscle 343–344, 346, 348, 350, 352, 354, 356, 358, 360 motility assay systems 119, 137, 139 motor domain 40–41, 275, 278–279, 281–282, 421, 434 motor proteins 376 motor unit activity 209–210, 218–220, 223, 225–227 mouse muscle 181, 183, 186 mouse muscle fibres 171, 235 muscle activated 56, 203, 222 invertebrate 346 lengthening 154, 160, 225–226 overstretched 86 relaxed 93–94, 98, 100–101 skinned 55, 84, 93 slow 250 muscle actin 417 muscle activation 193–194, 202, 210, 213, 219, 226, 228, 285 muscle axis 51, 57 muscle-based thermogenesis 316 muscle biologists 35 muscle biophysics 103 muscle cells 55, 77, 79–80, 87–89, 92, 96, 100, 102, 416–417 activated 251–252 isolated smooth 288 real life 79 striated 75 muscle contractile proteins 35, 243 muscle contractility 310 muscle contraction skeletal 194 static 223 voluntary 219, 223 muscle development 318 muscle diffraction experiments 45 muscle efficiency 254, 262 muscle energetics 250–251, 253, 263 muscle fatigue 213, 260–261 muscle fiber contraction 118, 136, 139 muscle fiber stiffness 225 muscle fibers 4–5, 118–119, 122–123, 133, 135, 137–138, 214, 219, 225–228, 356 force-generating capacity of 212, 220 mammalian 254, 284 rabbit psoas 260, 262 skinned 25, 28, 30, 119, 131, 134 skinned skeletal 25 slow 260, 263 muscle filaments 5, 46, 87 muscle mechanics 8, 123, 210 muscle physiology 118 human skeletal 215 muscle proteins 9, 49, 77, 100, 102, 157 muscle regulation 201 muscle sarcomere 36, 64 muscle shear modulus 209–210, 215–216, 218–219, 221, 223–228 muscle shortening 61, 153, 160–161, 225, 249, 252–253, 262 muscle stiffness 210, 216 muscle stimulation 195, 358 Index muscle stretch 198, 228 mutations 285, 289, 291, 308–309, 433 sarcomeric 262 MVC, see maximal voluntary contraction MyHC, see myosin heavy chains myosin-associated kinase 357, 360 myosin head theory, traditional 350–351 myosin heavy chain (MHC) 259–260, 262 myosin heavy chains (MyHC) 273–275, 278–279, 282–283 myosin II 274, 276, 282, 394–396, 401–402, 405, 421, 423–426, 428–430, 433–434 myosin II binding 429, 434 myosin II distribution 394, 402 myosin II filaments 429 bipolar 390 myosin II localization 401 myosin II motor molecules 393–394 myosin II motors 434 myosin inhibitors 358 myosin lever arm 290 myosin light chain (MLC) 263, 273–282, 284, 286, 288, 290, 334, 336, 346–347, 355 myosin light chain kinase (MLCK) 280, 334, 347 myosin molecules 5–6, 13, 36, 38, 93, 97, 119, 122, 125, 127, 129, 211, 251, 274, 281 myosin motility 433 myosin motors 274, 432, 434–435 myosin movement 18, 433 myosin rod 40–41, 93 myosin stiffness 281, 290 myosin–actin interaction 193–194, 196, 199, 202 neutrophils 388, 390, 397–398, 403–404 non-muscle cells turnover 419 paramyosin 346, 349 peptides 12, 118, 129, 131, 353–354 phosphate 39, 87, 89, 93, 99, 101, 103 phospholamban 304–305, 307, 314–315 phosphorylation 92, 101, 185, 280, 307–308, 316, 347, 353–355, 357, 373 PKA, see PLN by protein kinase A PLN by protein kinase A (PKA) 259, 304–305, 307–308, 312, 345, 347 PLN gene 308–309, 312 PLN mutations 308 polarity generation 387, 405 power stroke 4, 7–8, 22, 24–26, 29–31, 122, 138, 210, 252, 260, 282 average amplitude of myosin head 25, 28 lever arm mechanism of myosin head 25, 32 mode of myosin head 31 451 452 Index proteins actin filament capping 85 living interacting structured 75 myosin binding 41, 251, 265 psoas muscle 146, 198 pyrophosphate 91, 93, 99 reactive lysine residue 12, 129, 131, 136–137 reactive oxygen species (ROS) 235–236, 244 recovery strokes 4, 8, 17–18, 20, 22, 29, 137 regulatory light chain (RLC) 13, 41, 91–92, 118, 129–130, 273, 275–276, 278–279, 281 residual force enhancement (RFE) 169–172, 174, 178, 181–182, 184–185, 187, 194, 203, 228 resting muscle tension 148 RFE, see residual force enhancement rigor muscle 49, 51, 55, 66, 101 rigor muscle tension 148 rigor state 77, 79, 83, 98, 210, 344, 350–351 RLC, see regulatory light chain ROS, see reactive oxygen species SAR, see sarcalumenin sarcalumenin (SAR) 304–305, 318–319 sarcolipin (SLN) 304–306, 315–317 sarcomere stiffness 172, 186–187, 193–194, 200, 202 sarcomeres 6, 36–40, 51, 60–62, 81–83, 85–86, 92, 96, 98, 100–102, 120, 148, 187, 200, 202–203 sarcomeric cytoskeleton 82, 85, 96, 101 sarcoplasmic reticulum (SR) 81, 84–85, 95, 197, 254, 259, 303–314, 316, 318–320 scallop myosin 285 SERCA activity 312–313, 315 SERCA1a 306, 316 SERCA2a 254, 303–308, 310, 312–315, 317, 320 down-regulation of 306 SERCA2a activity 305, 307, 309, 312–313, 316 SERCA2a protein 304–306 SERCA2a pump activity 304–305, 317, 320 serotonin 343–345, 347–349, 352, 357 skeletal muscle fast 261, 289 fast-twitch 276, 286, 315 fiber types 259 human 320, 416 slow 276 slow-twitch 276, 315 skeletal muscle fibers 273 skeletal muscle myosin 274–275, 277, 282 skeletal muscle myosin II 274, 433–434 skeletal muscle titin isoforms 201 sliding filament theory 77, 81, 89, 94 Index SLN, see sarcolipin smooth muscle 276, 288, 334, 338, 346–347, 350, 357, 359 smooth muscle cells 273, 338, 400 smooth muscle myosin-II 285 soleus muscle 186, 260 sperm flagella 371–374, 376, 378, 380, 382, 384 sphingosylphosphorylcholine 334–336, 338 SR, see sarcoplasmic reticulum SR calcium ATPase 254, 303–305 SR lumen 304–306 SSI, see supersonic shear imaging static stiffness 174, 180–183, 186, 199, 239 static tension 169–172, 174–187, 193–201, 203 stretch resistance 352–353, 355–356 striated muscle 36, 38, 48, 79, 120, 194, 200, 318, 346 striated muscle contraction 75, 79 subarachnoid hemorrhage 334 substratum 23, 387–391, 396–405 elastic 397, 400 periodic stretching of 391 supersonic shear imaging (SSI) 209–210, 212–218, 220, 222–224, 226–228 supertwisting 420–421, 426 T-jump, see temperature-jump T-jump tension 153, 157 temperature-jump (T-jump) 143–145, 147–148, 152–161 tendons 146, 172–174, 220, 237, 251, 265 tension recovery 90, 147, 159, 243 tetanic contractions 56, 58, 67, 195–196, 220, 222–223, 240 tetanic tension 148, 152–153, 183, 240 tetanus plateau 171, 174, 179, 181 tibialis anterior muscle 220–223 tetanized 220–221 titin 77, 82, 85–87, 96, 98–99, 101–102, 170–171, 184–186, 193–194, 196, 198, 200–203, 251, 261, 265 titin filaments 97–98, 101, 148, 170–171, 180 titin isoforms 198–199 titin molecules 40, 194, 198, 201, 203 titin stiffening 171, 184–186 titin stiffness 185–186, 193, 200–203 titin–actin interaction 183, 185, 187, 200, 202 tropomyosin 6, 38, 40, 82, 84, 120, 285, 424 tropomyosin strands 42 troponin 6, 38, 40, 42, 47, 60, 82, 84, 86, 93, 98–99, 120, 198, 277, 285 twitch tension 196 twitchin 346–348, 352–355, 357, 359 dephosphorylation of 348 twitchin kinase 355, 357 453 454 Index twitchin phosphorylation 347, 353–354 twitchin segments 353–354, 359 vascular smooth muscle (VSM) 333–335, 337 vasospasm 333–339 ventricular muscle 315 ventricular myosin light chain (VLC-1) 276, 286–287 vertebrate muscles 53 VLC-1, see ventricular myosin light chain VSM, see vascular smooth muscle VSM cells 336 VSM contraction 335, 338 wound healing 387–388 X-ray diffraction 35–36, 42, 44, 50, 67, 77–78, 160 X-rays 35, 41–42, 45, 50, 88, 91 yeasts 416–417, 433 ... brevis muscle at 22 24 °C Fibres were repetitively stimulated to induce fatigue and then force and stiffness recovery were followed during Muscle Contraction and Cell Motility: Fundamentals and Developments... activation patterns in elbow flexor muscles during isometric, concentric and eccentric contractions Eur J Appl Physiol, 66: 21 4 22 0 23 1 23 2 Stiffness of Contracting Human Muscle Measured with Supersonic... significant positive association of muscle force with shear modulus (R2 = 0. 52, n = 45, P < 0.001) (adapted from Sasaki et al., 20 14) 22 1 22 2 Stiffness of Contracting Human Muscle Measured with Supersonic