Effects of chronic stimulation on the size and speed of long‐term denervated and innervated rat fast and slow skeletal muscles

Hennig, R.; Lømo, Terje

doi:10.1111/j.1748-1716.1987.tb08118.x

Cited by 60 publications

(43 citation statements)

References 45 publications

(23 reference statements)

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“…As a matter of fact, since a growth-induced increase in SEC stiffness in soleus muscle was also found, this may shorten the twitch and hence take part in the reduction of the twitch kinetic parameters in this muscle. Differences in twitch kinetics reported in this study between fast EDL and slow soleus muscles were in accordance with the literature for adult rats (Hennig and Lomo, 1987;Gundersen and Eken, 1992) and were related to the different fibre-type distribution between these muscles. Resistance to fatigue was more pronounced in adult soleus muscle in comparison to weaning age even though no difference was observed for EDL muscle.…”

Section: Discussionsupporting

confidence: 80%

Differential adaptations during growth spurt and in young adult rat muscles

Barros

Manhães-de-Castro

Goubel

et al. 2009

Animal

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During the post-weaning growth and maturation period (25/90 days after birth), rat limb muscles are submitted to specific adaptations. Our aim was to characterize the mechanical properties of two muscles that are opposite in terms of fibre-type distribution, the soleus and the extensor digitorum longus (EDL) muscles of male Wistar rats. Results showed a fast-to-slow fibretype transition in soleus while no modification in fibre-type distribution was observed in EDL. A growth-induced increase in muscle force was observed. Soleus underwent an increase in twitch kinetics, but EDL showed no modification. Resistance to fatigue was higher in 90-day-old soleus but not modified in the EDL. Surprisingly, analysis of maximal shortening velocity showed a decrease in both soleus and EDL. Finally, tension/extension curves indicated a growth-induced increase in series elastic stiffness in the two muscles. These results suggest that during this growth period, skeletal muscles are submitted to differential adaptations. Moreover, whereas adaptation of biomechanical properties observed can be explained partly by an adaptation of fibre profile in soleus, this is not the case for EDL. It is suggested that changes in muscle architecture, which are often disregarded, could explain some variations in mechanical properties, especially when muscles undergo an increase in both mass and length.

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Section: Discussionsupporting

confidence: 80%

Differential adaptations during growth spurt and in young adult rat muscles

Barros

Manhães-de-Castro

Goubel

et al. 2009

Animal

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“…There have been some reports of the activity patterns of single motor units over prolonged periods from muscles of a predominant phenotype (Fishbach and Robbins, 1969;Hennig and Lomo, 1987). In these cases, however, there was a high probability that the recordings were from the most excitable (smaller) motor units.…”

Section: Hypothetical Muscle Fiber Recruitment Modelmentioning

confidence: 99%

“…fiber type composition Since the activity levels of a muscle can modulate the muscle fiber phenotype over a period of weeks (Al-Amood et al, 1991;Booth and Baldwin, 1996;Eisenberg et al, 1984;Hennig and Lomo, 1987;Lewis et al, 1997;Vrbova, 1992, 1999;Roy et al, 1991c;Windsich et al, 1998), we examined the degree to which these two variables are coupled. Of the hindlimb muscles for which normal daily EMG activity has been studied (Fig.·5A), the soleus muscle has one of the highest percentages (~70-100%) of slow fibers in all species (Fig.·5B).…”

Section: Lack Of a Close Relationship Between Muscle Activity Level Andmentioning

confidence: 99%

“…Furthermore, chronic electrical stimulation paradigms often result in fiber atrophy in muscles of control rats (Eisenberg et al, 1984) and are ineffective in maintaining the size of inactivated or unloaded muscles (Al Amood et al, 1991;Canon et al, 1998;Hennig and Lomo, 1987;Leterme and Falempin, 1994). In contrast, short bouts of load-bearing Daily activity levels of rat hindlimb muscles activity attenuate the loss of muscle mass associated with chronic periods of decreased neuromuscular activity (Roy et al, 1991c;Edgerton and Roy, 1996).…”

mentioning

confidence: 99%

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Does daily activity level determine muscle phenotype?

Hodgson

Roy

Higuchi

et al. 2005

Journal of Experimental Biology

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SUMMARY The activation level of a muscle is presumed to be a major determinant of many mechanical and phenotypic properties of its muscle fibers. However, the relationship between the daily activation levels of a muscle and these properties has not been well defined, largely because of the lack of accurate and sustained assessments of the spontaneous activity levels of the muscle. Therefore, we determined the daily activity levels of selected rat hindlimb muscles using intramuscular EMG recordings. To allow comparisons across muscles having varying activity levels and/or muscle fiber type compositions,we recorded EMG activity in a predominantly slow plantarflexor (soleus), a predominantly fast plantarflexor (medial gastrocnemius, MG), a predominantly fast ankle dorsiflexor (tibialis anterior, TA) and a predominantly fast knee extensor (vastus lateralis, VL) in six unanesthetized rats for periods of 24 h. EMG activity levels were correlated with the light:dark cycle, with peak activity levels occurring during the dark period. The soleus was the most active and the TA the least active muscle in all rats. Daily EMG durations were highest for soleus (11–15 h), intermediate for MG (5–9 h) and VL (3–14 h) and lowest for TA (2–3 h). Daily mean EMG amplitudes and integrated EMG levels in the soleus were two- to threefold higher than in the MG and VL and seven- to eightfold higher than in the TA. Despite the three- to fourfold difference in activation levels of the MG and VL vs the TA, all three predominantly fast muscles have been reported to have a similar, very low percentage of slow fibers. Comparing these relative EMG levels to the published fiber type profiles of these muscles yields a very poor relationship between daily activity level and fiber type composition in the same muscles across several species. Although it is clear that changing the levels of activity can modulate the expression of the myosin phenotype,these results indicate that factors other than activation must play critical roles in determining and maintaining normal phenotypic properties of skeletal muscle fibers.

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“…Although this technique did not distinguish between satellite cells and myonuclei, the finding opens up the possibility that there is no loss of myonuclei even after very long disuse periods. If nuclei and fiber integrity persist even in the extremely atrophic fibers induced by long-term disuse, this might explain the remarkable recovery of muscle strength when nerve activity is restored or substituted by electrodes even after prolonged inactivity both in rodents (46) and in humans (47).…”

Section: Figurementioning

confidence: 99%

In vivo time-lapse microscopy reveals no loss of murine myonuclei during weeks of muscle atrophy

Bruusgaard¹,

Gundersen²

2008

J. Clin. Invest.

151

177

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Numerous studies have suggested that muscle atrophy is accompanied by apoptotic loss of myonuclei and therefore recovery would require replenishment by muscle stem cells. We used in vivo time-lapse microscopy to observe the loss and replenishment of myonuclei in murine muscle fibers following induced muscle atrophy. To our surprise, imaging of single fibers for up to 28 days did not support the concept of nuclear loss during atrophy. Muscles were inactivated by denervation, nerve impulse block, or mechanical unloading. Nuclei were stained in vivo either acutely by intracellular injection of fluorescent oligonucleotides or in time-lapse studies after transfection with a plasmid encoding GFP with a nuclear localization signal. We observed no loss of myonuclei in fast-or slow-twitch muscle fibers despite a greater than 50% reduction in fiber cross-sectional area. TUNEL labeling of fragmented DNA on histological sections revealed high levels of apoptotic nuclei in inactive muscles. However, when costained for laminin and dystrophin, virtually none of the TUNEL-positive nuclei could be classified as myonuclei; apoptosis was confined to stromal and satellite cells. We conclude that disuse atrophy is not a degenerative process, but is rather a change in the balance between protein synthesis and proteolysis in a permanent cell syncytium.

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Effects of chronic stimulation on the size and speed of long‐term denervated and innervated rat fast and slow skeletal muscles

Cited by 60 publications

References 45 publications

Differential adaptations during growth spurt and in young adult rat muscles

Differential adaptations during growth spurt and in young adult rat muscles

Does daily activity level determine muscle phenotype?

In vivo time-lapse microscopy reveals no loss of murine myonuclei during weeks of muscle atrophy

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