Length-dependent potentiation and myosin light chain phosphorylation in rat gastrocnemius muscle

Rassier, Dilson E.; Tubman, L. Aaron; MacIntosh, Brian R.

doi:10.1152/ajpcell.1997.273.1.c198

Cited by 30 publications

(33 citation statements)

References 25 publications

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“…Staircase potentiation was inversely related to fiber bundle length at pH levels of 7.4 and 7.8, as previously reported in muscles stimulated in situ and at physiological pH (19)(20)(21), or in vitro at pH 7.4 (11). In previous studies, we observed that this length dependence of potentiation was directly associated with the length dependence of Ca 2ϩ sensitivity.…”

Section: Discussionsupporting

confidence: 85%

“…Potentiation is greater when the contractile response is measured at short compared with long muscle lengths (19-21). However, RLC phosphorylation is not muscle length dependent (20). Therefore the force-potentiating effects of phosphorylation must be different at different lengths, and factors other than RLC phosphorylation must produce the length-dependent effect.…”

mentioning

confidence: 99%

“…Twitch potentiation is muscle length dependent. Potentiation is greater when the contractile response is measured at short compared with long muscle lengths (19)(20)(21). However, RLC phosphorylation is not muscle length dependent (20).…”

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confidence: 99%

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Effects of pH on the length-dependent twitch potentiation in skeletal muscle

Rassier

Herzog

2002

Journal of Applied Physiology

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Rassier, Dilson E., and Walter Herzog. Effects of pH on the length-dependent twitch potentiation in skeletal muscle. J Appl Physiol 92: 1293-1299, 2002; 10.1152/japplphysiol. 00912.2001.-When muscle is elongated, there is a length dependence of twitch potentiation and an increased Ca 2ϩ sensitivity of the myofilaments. Changes in the charge potential of myofilaments, induced by a decrease in pH, are known to abolish the length dependence of Ca 2ϩ sensitivity. This study was aimed at testing the hypothesis that a decrease in pH, and the concomitant loss of length dependence of Ca 2ϩ sensitivity, depresses the length dependence of staircase potentiation. In vitro, isometric twitch contractions of fiber bundles dissected from the mouse extensor digitorum longus, performed before and after 10 s of 10-Hz stimulation (i.e., the staircase potentiation protocol) were analyzed at five different lengths, ranging from optimal length for maximal force production (L o; ϭ 12 Ϯ 0.7 mm) to Lo ϩ 1.2 mm (Lo ϩ 10%). These measurements were made at an extracellular pH of 6.6, 7.4, and 7.8 (pH changes induced by altering the CO 2 concentration of the bath solution). At pH 7.4 and 7.8, the degree of potentiation after 10-Hz stimulation showed a linear decrease with increased fiber bundle length (r 2 ϭ 0.95 and r 2 ϭ 0.99, respectively). At pH 6.6, the length dependence of potentiation was abolished, and the slope of the length-potentiation relationship was not different from zero (r 2 ϭ 0.05). The results of this study indicate that length dependence of potentiation in intact skeletal muscle is abolished by lowering the pH. Because decreasing the pH decreases Ca 2ϩ sensitivity and changes the charge potential of the filaments, the mechanism of length-dependent potentiation may be closely related to the length dependence of Ca 2ϩ sensitivity, and changes in the charge potential of the myofilaments may be important in regulating this relationship.force-length relation; Ca 2ϩ sensitivity; force potentiation; twitch force FORCE PRODUCTION IN SKELETAL muscle depends on many variables. Among these, length, speed of contraction, and the history of the contractile conditions have been well studied (2,7,8). Other variables have received less attention in the biomechanical community, and mechanistic explanations that relate these variables to force production are rare. These include force potentiation after tetanic and staircase contractions and the shift of submaximal force-length relationships to the right of the length axis compared with maximal force-length relationships. In this study, we tried to gain insight into the mechanisms of staircase potentiation as a function of muscle length.Staircase potentiation is the increase in active twitch force that occurs for the first seconds of repetitive skeletal muscle stimulation. Staircase potentiation is important for in vivo skeletal muscle contractions, because it occurs at frequencies of stimulation that are within the physiological range (12). The degree of potentiation in intact muscles is...

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Section: Discussionsupporting

confidence: 85%

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confidence: 99%

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Effects of pH on the length-dependent twitch potentiation in skeletal muscle

Rassier

Herzog

2002

Journal of Applied Physiology

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“…In rat muscle, twitch potentiation is inversely proportional to muscle length, the magnitude of the enhancement being greater at shorter muscle lengths (Rassier et al 1997;Rijkelijkhuizen et al 2005). …”

Section: Muscle Activation Between Knee Anglesmentioning

confidence: 99%

“…It has further been shown that the diVerence in endurance (time to torque failure) between knee angles does not originate from diVerences in central drive at the point of torque failure or from diVerences in muscle perfusion (Kooistra et al 2005). However, potentiation, the enhancement of contractile response as a consequence of prior activation, has been suggested to contribute to the increased endurance at extended compared to Xexed knee angles (Place et al 2005) as potentiation is greater at short compared to long muscle length in rats (Rassier et al 1997;Rijkelijkhuizen et al 2005). Furthermore, potentiation may lead to a constant force output despite a decline in motor unit Wring rate (Klein et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Knee extensor muscle oxygen consumption in relation to muscle activation

et al. 2006

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Recently, fatigability and muscle oxygen consumption (mVO 2 ) during sustained isometric contractions were found to be less at shorter (30° knee angle; 0°= full extension) compared to longer knee extensor muscle lengths (90°) and, at low torques, less in the rectus femoris (RF) muscle than in the vastus lateralis and medialis. In the present study we hypothesized that these Wndings could be accounted for by a knee angle-and a muscle-dependent activation respectively. On two experimental days rectiWed surface EMG (rsEMG) was obtained as a measure of muscle activation in nine healthy young males. In addition, on day 1 maximal torque capacity (MTC) was carefully determined using superimposed nerve stimulation on brief high intensity contractions (> 70%MVC) at 30, 60 and 90° knee angles. On day 2, subjects performed longer lasting isometric contractions (10-70%MTC) while mVO 2 was measured using near-infrared spectroscopy (NIRS). At 30°, maximal mVO 2 was reached signiWcantly later (11.0 s § 6.5 s) and was 57.9 § 8.3% less (average § SD, across intensities and muscles) than mVO 2 at 60 and 90° (p < 0.05). However, rsEMG was on average only 18.0 § 11.8% (p = 0.062) less at the start of the contraction at 30°. At 10%MTC at all knee angles, maximal mVO 2 of the RF occurred signiWcantly later (28.8 § 36.0 s) and showed a signiWcantly smaller increase in rsEMG compared to both vasti. In conclusion, it is unlikely that the tendency for less intense muscle activation could fully account for the »60% lower oxygen consumption at 30°, but the later increase in RFmVO 2 seemed to be caused by a less strong activation of the RF.

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Modulation of Skeletal Muscle Contraction by Myosin Phosphorylation

Vandenboom

2016

Comprehensive Physiology

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The striated muscle sarcomere is a highly organized and complex enzymatic and structural organelle. Evolutionary pressures have played a vital role in determining the structure-function relationship of each protein within the sarcomere. A key part of this multimeric assembly is the light chain-binding domain (LCBD) of the myosin II motor molecule. This elongated "beam" functions as a biological lever, amplifying small interdomain movements within the myosin head into piconewton forces and nanometer displacements against the thin filament during the cross-bridge cycle. The LCBD contains two subunits known as the essential and regulatory myosin light chains (ELC and RLC, respectively). Isoformic differences in these respective species provide molecular diversity and, in addition, sites for phosphorylation of serine residues, a highly conserved feature of striated muscle systems. Work on permeabilized skeletal fibers and thick filament systems shows that the skeletal myosin light chain kinase catalyzed phosphorylation of the RLC alters the "interacting head motif" of myosin motor heads on the thick filament surface, with myriad consequences for muscle biology. At rest, structure-function changes may upregulate actomyosin ATPase activity of phosphorylated cross-bridges. During activation, these same changes may increase the Ca2+ sensitivity of force development to enhance force, work, and power output, outcomes known as "potentiation." Thus, although other mechanisms may contribute, RLC phosphorylation may represent a form of thick filament activation that provides a "molecular memory" of contraction. The clinical significance of these RLC phosphorylation mediated alterations to contractile performance of various striated muscle systems are just beginning to be understood. © 2017 American Physiological Society. Compr Physiol 7:171-212, 2017.

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Length-dependent potentiation and myosin light chain phosphorylation in rat gastrocnemius muscle

Cited by 30 publications

References 25 publications

Effects of pH on the length-dependent twitch potentiation in skeletal muscle

Effects of pH on the length-dependent twitch potentiation in skeletal muscle

Knee extensor muscle oxygen consumption in relation to muscle activation

Modulation of Skeletal Muscle Contraction by Myosin Phosphorylation

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