Measuring Mechanical Properties, Including Isotonic Fatigue, of Fast and Slow MLC/mIgf-1 Transgenic Skeletal Muscle

Prete, Zaccaria Del; Musarò, Antonio; Rizzuto, Emanuele

doi:10.1007/s10439-008-9496-x

Cited by 36 publications

(40 citation statements)

References 48 publications

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“…3). The effects of muscle IGF-1 on muscle force are analyzed in MLC/mIgf-1 transgenic mice, in which the local expression of Igf-1 is increased in fast-twitch muscles such as EDL muscle at high levels (5,18). In EDL muscle in MLC/mIgf-1 transgenic mice, muscle mass is increased.…”

Section: Discussionmentioning

confidence: 99%

β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

Kitakaze

Harada

Imagita

et al. 2015

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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Summary Supplements and naturally occurring nutraceuticals effective for maintenance or enhancement of skeletal muscle mass are expected to contribute to prevention of decreased mobility and increased risk of developing metabolic diseases. However, information about available food components remains widely unavailable. In the present study, we investigated the effects of dietary b-carotene on the quantity and quality of skeletal muscle under physiological conditions. Male ddY mice (8 wk old) were orally administered b-carotene (0.5 mg once daily) for 14 d. Dietary b-carotene had no influence on body weight, but increased the soleus muscle/body weight ratio. The cross-sectional area (CSA) in muscle fibers of the soleus muscle was increased, indicating that administration of b-carotene induces muscle hypertrophy. In the soleus muscle of the b-carotene-administered mice, twitch force tended to be increased (p50.06) and tetanic force was significantly increased, whereas specific force (force per CSA) remained unchanged. Dietary b-carotene increased the mRNA level of insulin-like growth factor 1 (Igf-1) as its splicing variant Igf-1ea, but had no influence on the liver Igf-1 mRNA level or serum IGF-1 level. b-Carotene promoted protein synthesis in the soleus muscle and reduced levels of ubiquitin conjugates, but had no influence on the mRNA levels of two atrogenes, Atrogin-1 and Murf1. On the other hand, b-carotene had no influence on the processing of the autophagy marker protein light chain 3. These results indicate that in mice, administration of b-carotene increases mass and induces functional hypertrophy in the soleus muscle, perhaps by promoting IGF-1-mediated protein synthesis and by reducing ubiquitin-mediated protein degradation.

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Section: Discussionmentioning

confidence: 99%

β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

Kitakaze

Harada

Imagita

et al. 2015

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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“…The method used to evaluate fatigue in isolated muscles was that of Del Prete et al (Del Prete et al, 2008). Isolated soleus and EDL were individually suspended in Krebs solution aerated with 95% O 2 and 5% CO 2 at room temperature (23° C).…”

Section: Methodsmentioning

confidence: 99%

TNF‐α‐mediated reduction in PGC‐1α may impair skeletal muscle function after cigarette smoke exposure

Tang

Wagner

Breen

2009

Journal Cellular Physiology

116

123

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Skeletal muscle dysfunction contributes to exercise limitation in COPD. In this study cigarette smoke exposure was hypothesized to increase expression of the inflammatory cytokine, TNF-α, and down stream molecules that regulate oxygen transport and muscle function. Furthermore, we hypothesized that highly-vascularized oxidative skeletal muscles would be more susceptible to the damaging effects of cigarette smoke compared to a less well-vascularized glycolytic muscle. To test these hypotheses mice were exposed to daily periods of cigarette smoke over 8 and 16-weeks resulting in 157% (8 wks) and 174% (16 wks) increases in serum TNF-α. Separately TNF-α administered to C2C12 myoblasts was found to dose dependently reduce PGC-1α mRNA. The vascular PGC-1α target molecule, VEGF, was also down-regulated but only in the soleus, which exhibited capillary regression and an oxidative to glycolytic fiber-type transition. The apoptosis PGC-1α target genes, atrogin-1 and MuRF1, were upregulated and to a greater extent in the soleus compared to the EDL. Citrate synthase (soleus −19%, EDL −17%) and β-hydroxyacyl CoA dehydrogenase (β-HAD) (soleus −22%, EDL −19%) decreased similarly in both muscle types. There was loss of body and gastrocnemius complex mass, with rapid soleus but not EDL fatigue and diminished exercise endurance. These data suggest that in response to smoke exposure, TNF-α mediated down-regulation of PGC-1α may be a key step leading to vascular and myocyte dysfunction, effects that are more evident in oxidative than glycolytic skeletal muscles.

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“…For many locomotive muscles, isotonic contractions, during which the muscle performs work, are also more physiological than isometric conditions. To date, only a few experimental studies specifically describe "isotonic fatigue," and it seems that the classical definitions of fatigue may not reflect deteriorating muscle function during these conditions (8,10,38,43,47).…”

mentioning

confidence: 98%

“…For instance, it is now clear that several effects of low pH on muscle contractility disappear as temperature is raised (35). Also biochemical reactions have different Q 10 . It is, therefore, quite probable that the rate-limiting step of a chain of reactions can vary with temperature.…”

mentioning

confidence: 98%

Causes of fatigue in slow-twitch rat skeletal muscle during dynamic activity

Munkvik¹,

Lunde²,

Sejersted³

2009

American Journal of Physiology-Regulatory, Integrative and Comp

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Skeletal muscle fatigue is most often studied in vitro at room temperature and is classically defined as a decline in maximum force production or power output, exclusively linked to repeated isometric contractions. However, most muscles shorten during normal use, and we propose that both the functional correlate of fatigue, as well as the fatigue mechanism, will be different during dynamic contractions compared with static contractions. Under isoflurane anesthesia, fatigue was induced in rat soleus muscles in situ by isotonic shortening contractions at 37 degrees C. Muscles were stimulated repeatedly for 1 s at 30 Hz every 2 s for a total of 15 min. The muscles were allowed to shorten isotonically against a load corresponding to one-third of maximal isometric force. Maximal unloaded shortening velocity (V(0)), maximum force production (F(max)), and isometric relaxation rate (-dF/dt) was reduced after 100 s but returned to almost initial values at the end of the stimulation protocol. Likewise, ATP and creatine phosphate (CrP) were reduced after 100 s, but the level of CrP was partially restored to initial values after 15 min. The rate of isometric force development, the velocity of shortening, and isotonic shortening were also reduced at 100 s, but in striking contrast, did not recover during the remainder of the stimulation protocol. The regulatory myosin light chain (MLC2s) was dephosphorylated after 100 s and did not recover. Although metabolic changes may account for the changes of F(max), -dF/dt, and V(0), dephosphorylation of MLC2s may be involved in the fatigue seen as sustained slower contraction velocities and decreased muscle shortening.

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Measuring Mechanical Properties, Including Isotonic Fatigue, of Fast and Slow MLC/mIgf-1 Transgenic Skeletal Muscle

Cited by 36 publications

References 48 publications

β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

TNF‐α‐mediated reduction in PGC‐1α may impair skeletal muscle function after cigarette smoke exposure

Causes of fatigue in slow-twitch rat skeletal muscle during dynamic activity

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Measuring Mechanical Properties, Including Isotonic Fatigue, of Fast and Slow MLC/mIgf-1 Transgenic Skeletal Muscle

Cited by 36 publications

References 48 publications

&beta;-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

&beta;-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

TNF‐α‐mediated reduction in PGC‐1α may impair skeletal muscle function after cigarette smoke exposure

Causes of fatigue in slow-twitch rat skeletal muscle during dynamic activity

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β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice

β-Carotene Increases Muscle Mass and Hypertrophy in the Soleus Muscle in Mice