Effect of “disuse” on mammalian fast-twitch muscle: Joint fixation compared with neurally applied tetrodotoxin

St-Pierre, Diane M. M.; Gardiner, Phillip F.

doi:10.1016/0014-4886(85)90161-x

Cited by 56 publications

(46 citation statements)

References 43 publications

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“…Rassier et al use atrophy, TTX is delivered continuously to the sciatic nerve for a period of two weeks. Since TTX is a sodium channel blocker, all nerve action potential propagation is stopped, and the affected muscles are completely quiescent during the period of application (6). It has also been shown that R-LC phosphorylation is significantly lower in TTX-disuse atrophied muscle after 10 s of 10-Hz repetitive stimulation in comparison with control or sham-treated muscles (8), suggesting that the direct relation between R-LC phosphorylation and staircase response is maintained in this model.…”

Section: Introductionmentioning

confidence: 79%

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Staircase in mammalian muscle without light chain phosphorylation

Rassier

Tubman

MacIntosh

1999

Braz J Med Biol Res

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In disuse atrophied skeletal muscle, the staircase response is virtually absent and light chain phosphorylation does not occur. The purpose of the present study was to determine if staircase could be restored in atrophied muscle with continued absence of myosin light chain phosphorylation, by reducing what appears to be an otherwise enhanced calcium release. Control (untreated) and sham-operated female Sprague-Dawley rats were compared with animals after 2 weeks of complete inactivity induced by tetrodotoxin (TTX) application to the left sciatic nerve. In situ isometric contractile responses of rat gastrocnemius muscle were analyzed before and after administration of dantrolene sodium (DS), a drug which is known to inhibit Ca 2+ release in skeletal muscle. Twitch active force (AF) was attenuated by DS from 2.2 ± 0.2 N, 2.7 ± 0.1 N and 2.4 ± 0.2 N to 0.77 ± 0.2 N, 1.05 ± 0.1 N and 1.01 ± 0.2 N in TTX (N = 5), sham (N = 11) and control (N = 7) muscles, respectively. Following dantrolene treatment, 10 s of 10-Hz stimulation increased AF to 1.32 ± 0.2 N, 1.52 ± 0.1 N and 1.45 ± 0.2 N for the TTX, sham and control groups, respectively, demonstrating a positive staircase response. Regulatory light chain (R-LC) phosphorylation was lower for TTX-treated (5.5 ± 5.5%) than for control (26.1 ± 5.3%) and sham (20.0 ± 5%) groups. There was no significant change from resting levels for any of the groups after DS treatment (P = 0.88). This study shows that treatment with dantrolene permits staircase in atrophied muscle as well as control muscle, by a mechanism which appears to be independent of R-LC phosphorylation.

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Section: Introductionmentioning

confidence: 79%

“…The staircase response is greatly attenuated in rat fast-twitch skeletal muscle that has been atrophied by disuse induced by chronic tetrodotoxin (TTX) application to the sciatic nerve (5)(6)(7). In this model of dis-D.E.…”

Section: Introductionmentioning

confidence: 99%

Staircase in mammalian muscle without light chain phosphorylation

Rassier

Tubman

MacIntosh

1999

Braz J Med Biol Res

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“…In animals, experimental data indicate that disuse is not only associated with decreased muscle force generating capacity (Witzmann, Kim & Fitts, 1982;St Pierre & Gardiner, 1985), but also with alterations of the electromyographic (EMG) activity (Fudema, Fizzell & Nelson, 1961;Fournier, Roy, Perham, Simard & Edgerton, 1983). This last observation suggests that the muscle membrane electrical activity is reduced and/or that neural changes are present.…”

Section: Introductionmentioning

confidence: 92%

Effects of immobilization on contractile properties, recruitment and firing rates of human motor units.

Duchateau¹,

Hainaut²

1990

The Journal of Physiology

179

120

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SUMMARY1. The contractile properties, recruitment and firing rates of motor units from the human adductor pollicis and the first dorsal interosseous were studied during voluntary isometric contractions after 6-8 weeks' immobilization of the corresponding limbs.2. In both muscles, motor units of different force thresholds showed a proportionally identical twitch tension decrease and slowing of their time course after immobilization.3. When expressed as a percentage of the maximal voluntary contraction, more high-threshold motor units were recorded in disused muscles than in control muscles, but the order of recruitment was maintained.4. The motor unit firing rate at recruitment was identical in control and disused muscles, but the maximal firing rate decreased in all motor units after immobilization. This decrease of the maximal firing rate was greater in motor units of lower threshold than in those of higher threshold.5. The results further document motoneuronal plasticity in human muscles of different fibre type composition.

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“…The atrophied muscle presents a higher twitch: double pulse contraction ratio than nonatrophied muscle (MacIntosh et al 1988) and a higher twitch: tetanus ratio (St-Pierre & Gardiner, 1985). Furthermore, the progressive enhancement in developed tension (staircase) which occurs during low frequency repetitive activation is absent in these muscles.…”

Section: Introductionmentioning

confidence: 97%

Inhibition of Ca2+ release in rat atrophied gastrocnemius muscle

Rassier

Tubman²,

MacIntosh³

1997

Experimental Physiology

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SUMMARYContractile parameters of a twitch contraction and changes in these parameters during repetitive stimulation are modified by muscle atrophy induced by tetrodotoxin (TTX). These altered parameters include developed tension (DT), contraction time (ta), half-relaxation time (tR,J), average rate of force development (DT tC 1) and peak rate of relaxation (DTdtmin-'). These modifications may be related to different Ca concentration transients in the myoplasm during muscle stimulation.We have used dantrolene sodium (DS) in TTX-treated rat gastrocnemius muscle to test this hypothesis. In situ isometric contractile responses of rat gastrocnemius muscle during repetitive stimulation at 10 Hz were analysed before and after administration of DS. After DS administration, twitch amplitude, tC tR5 and DTtc-1 decreased and DTdtmin-I relative to DT increased in atrophied muscle. During repetitive stimulation, a progressive enhancement in developed tension (staircase) was absent in atrophied muscle, but DT increased to 171 + 4 %, presenting a staircase response after DS treatment. This potentiation was accompanied by an increase in DT tc1 to 175.6 + 7 %. Inhibition of Ca2+release in atrophied muscle resulted in twitch contractile parameters and contractile responses to 10 Hz stimulation that were similar, in many respects, to those responses in control (non-atrophied) muscles.

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Effect of “disuse” on mammalian fast-twitch muscle: Joint fixation compared with neurally applied tetrodotoxin

Cited by 56 publications

References 43 publications

Staircase in mammalian muscle without light chain phosphorylation

Staircase in mammalian muscle without light chain phosphorylation

Effects of immobilization on contractile properties, recruitment and firing rates of human motor units.

Inhibition of Ca2+ release in rat atrophied gastrocnemius muscle

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