Interaction of posttetanic potentiation and the catchlike property in mouse skeletal muscle

Gittings, William; Bunda, Jordan; Vandenboom, Rene

doi:10.1002/mus.25053

Cited by 12 publications

(5 citation statements)

References 31 publications

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“…The levels of RLC phosphorylation we observed following lowfrequency stimulation producing staircase potentiation are similar to those reported previously using similar stimulus protocols (MacIntosh et al, 1993) or similar muscle models (Moore et al, 1990). Consistent with previous work comparing the two genotypes, we found that RLC phosphorylation was increased by stimulation in WT but not in skMLCK −/− muscles (Bowslaugh et al, 2016;Gittings et al, 2011Gittings et al, , 2016Zhi et al, 2005). These data confirm the critical influence of skMLCK for stimulation-induced RLC phosphorylation levels.…”

Section: Myosin Rlc Phosphorylationsupporting

confidence: 91%

“…In parallel experiments, a subset of muscles were removed from −80°C storage and myosin RLC phosphate content was quantified half-relaxation time skMLCK −/− myosin light chain kinase knockout (skeletal muscle isoform) TPT time to peak tension V max maximal shortening velocity by urea-glycerol PAGE followed by immunoblotting. These methods were based on Zhi et al (2005) and have been described in detail previously (see Gittings et al, 2016;Bowslaugh et al, 2016). The primary myosin RLC antibody used in this work was graciously donated by Dr Jim Stull and his lab at the University of Texas Southwestern Medical Center.…”

Section: Myosin Rlc Phosphorylationmentioning

confidence: 99%

“…unless otherwise stated. Sample sizes (n) used to achieve statistical power were based upon previous work from our lab and others for both mechanical (Gittings et al, 2011(Gittings et al, , 2012(Gittings et al, , 2016Abbate et al, 2001) and biochemical (Zhi et al, 2005;Zhang et al, 2006) analyses. .…”

Section: Statisticsmentioning

confidence: 99%

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Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation

Bunda

Gittings

Vandenboom

2018

Journal of Experimental Biology

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Phosphorylation of the myosin regulatory light chain (RLC) by skeletal myosin light chain kinase (skMLCK) potentiates rodent fast twitch muscle but is an ATP-requiring process. Our objective was to investigate the effect of skMLCK-catalyzed RLC phosphorylation on the energetic cost of contraction and the contractile economy (ratio of mechanical output to metabolic input) of mouse fast twitch muscle (25°C). To this end, extensor digitorum longus (EDL) muscles from wild-type (WT) and from skMLCK-devoid (skMLCK) mice were subjected to repetitive low-frequency stimulation (10 Hz for 15 s) to produce staircase potentiation of isometric twitch force, after which muscles were quick frozen for determination of high-energy phosphate consumption (HEPC). During stimulation, WT muscles displayed significant potentiation of isometric twitch force while skMLCK muscles did not (i.e. 23% versus 5% change, respectively). Consistent with this, RLC phosphorylation was increased ∼3.5-fold from the unstimulated control value in WT but not in skMLCK muscles. Despite these differences, the HEPC of WT muscles was not greater than that of skMLCK muscles. As a result of the increased contractile output relative to HEPC, the calculated contractile economy of WT muscles was greater than that of skMLCK muscles. Thus, our results suggest that skMLCK-catalyzed phosphorylation of the myosin RLC increases the contractile economy of WT mouse EDL muscle compared with skMLCK muscles without RLC phosphorylation.

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Section: Myosin Rlc Phosphorylationsupporting

confidence: 91%

Section: Myosin Rlc Phosphorylationmentioning

confidence: 99%

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Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation

Bunda

Gittings

Vandenboom

2018

Journal of Experimental Biology

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“…Interestingly, Gittings et al (17) observed a reduced effect of a doublet in muscles that had received potentiating stimuli before the doublet stimulation. Based on this, it was argued that posttetanic potentiation may limit the positive effects of doublet stimulation (17). In contrast to this, our findings revealed similar activity-dependent potentiation for CFT and DT stimulation with respect to work and power.…”

Section: Discussionmentioning

confidence: 99%

Contractile benefits of doublet-initiated low-frequency stimulation in rat extensor digitorum longus muscle exposed to high extracellular [K⁺] or fatiguing contractions

Pedersen

Nielsen

Overgaard

2019

American Journal of Physiology-Cell Physiology

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During dynamic contractions, high-frequency muscle activation is needed to achieve optimal power. This must be balanced against an increased excitation-induced accumulation of extracellular K+, which can reduce excitability and ultimately may prevent adequate responses to high-frequency activation. Mean activation frequencies in vivo are often low (subtetanic), but activation patterns contain bursts of high (supratetanic) frequencies known as doublets, which enhance dynamic contraction in rested muscles at normal extracellular K+ concentration ([K+]o). Here, we examine how dynamic contractions in fast-twitch fibers stimulated by high frequency/doublets are affected during exposure to 11 mM [K+]o and during fatigue. Dynamic contractions were elicited by electrical stimulation in isolated rat extensor digitorum longus muscles incubated at 4 or 11 mM K+. When stimulation frequency was maintained constant, an increase from 150 to 300 Hz enhanced maximal power (Pmax), maximal velocity ( Vmax), and rate of force development (RFD) at 4 mM K+ but only Vmax at 11 mM K+. With the use of subtetanic frequency trains (50 Hz) with or without an initiating doublet (300 Hz), the addition of a doublet increased maximal force, Pmax, Vmax, and RFD at both 4 and 11 mM K+. Furthermore, a work-matched fatiguing protocol was performed comparing a doublet-initiated subtetanic train (DT) of 60 Hz with a constant-frequency train (CFT) of 71 Hz during 100 dynamic contractions. We found that DT produced higher power, velocity, and RFD than CFT throughout the fatiguing protocol. The results indicate that doublets enhance dynamic contraction in fast-twitch muscles stimulated at subtetanic frequency during both normal and fatiguing conditions.

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“…Interestingly, recently it was found that in a skeletal myosin light chain kinase knock-out (skMLCK−/−) mouse, the extensor digitorum longus (EDL) muscle exhibits no post-tetanic force potentiation after potentiating stimuli compared to that in wild-type control mice (Gittings et al 2016). This observation highlights the link between RLC phosphorylation in force potentiation as without skMLCK, the majority of skRLC would remain non-phosphorylated.…”

Section: Structure Isoforms Phosphorylation Sites and Function Of Rlcmentioning

confidence: 99%

Phosphorylation of the regulatory light chain of myosin in striated muscle: methodological perspectives

Chakravorty

Song

et al. 2016

Eur Biophys J

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Phosphorylation of the regulatory light chain (RLC) of myosin modulates cellular functions such as muscle contraction, mitosis, and cytokinesis. Phosphorylation defects are implicated in a number of diseases. Here we focus on striated muscle where changes in RLC phosphorylation relate to diseases such as hypertrophic cardiomyopathy and muscular dystrophy, or age-related changes. RLC phosphorylation in smooth muscle and non-muscle cells are covered briefly where relevant. There is much scientific interest in controlling the phosphorylation levels of RLC in vivo and in vitro in order to understand its physiological function in striated muscles. A summary of available and emerging in vivo and in vitro methods is presented. The physiological role of RLC phosphorylation and novel pathways are discussed to highlight the differences between muscle types and to gain insights into disease processes.

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Interaction of posttetanic potentiation and the catchlike property in mouse skeletal muscle

Cited by 12 publications

References 31 publications

Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation

Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation

Contractile benefits of doublet-initiated low-frequency stimulation in rat extensor digitorum longus muscle exposed to high extracellular [K⁺] or fatiguing contractions

Phosphorylation of the regulatory light chain of myosin in striated muscle: methodological perspectives

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Interaction of posttetanic potentiation and the catchlike property in mouse skeletal muscle

Cited by 12 publications

References 31 publications

Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation

Myosin phosphorylation improves contractile economy of mouse fast skeletal muscle during staircase potentiation

Contractile benefits of doublet-initiated low-frequency stimulation in rat extensor digitorum longus muscle exposed to high extracellular [K+] or fatiguing contractions

Phosphorylation of the regulatory light chain of myosin in striated muscle: methodological perspectives

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Contractile benefits of doublet-initiated low-frequency stimulation in rat extensor digitorum longus muscle exposed to high extracellular [K⁺] or fatiguing contractions