Responses of ankle plantar-flexors to various inhibitions of muscular activities in rats.

Ohara, Makoto; Yoshinaga, Tetsutaro; Tanaka, Takato; Ohira, Yoshinobu

doi:10.2187/bss.10.112

Cited by 5 publications

(5 citation statements)

References 11 publications

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“…It is also indicated that the neurons distributed at the L 5 may also innervate other muscles and/or tissues. For example, the EMG activity of MG did not change and that of TA was even increased slightly (P Ͼ 0.05) in response to unloading, as was mentioned above (12,18,22). Thus the responses of soleus EMG and the efferent neurogram recorded at the L 5 may not be correlated.…”

Section: Acute Responses Of Neuromuscular Activitiesmentioning

confidence: 87%

“…Ohara et al (18) reported that suspension-related atrophy of soleus muscle was not promoted when tenotomy of ankle extensors, denervation, or both tenotomy and denervation were performed in addition to hindlimb suspension. These data suggest that the decreases of EMG and afferent neurogram associated with the passive shortening of soleus, which inhibits tension development and afferent input, reach the maximum levels by plantarflexion of ankle joint alone during hindlimb suspension.…”

Section: Acute Responses Of Neuromuscular Activitiesmentioning

confidence: 99%

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Tension- and afferent input-associated responses of neuromuscular system of rats to hindlimb unloading and/or tenotomy

Kawano¹,

Ishihara²,

Stevens³

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

122

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Responses of electromyogram (EMG) in soleus muscle and both afferent and efferent neurograms at the fifth lumbar (L(5)) segmental level of spinal cord were investigated during acute and chronic unloading induced by hindlimb suspension and/or tenotomy in adult rats. The soleus EMG and afferent neurogram decreased 88 and 37%, respectively, relative to those at quadrupedal posture on the floor after acute hindlimb suspension that causes passive shortening of soleus due to ankle plantarflexion. However, the afferent neurogram (P < 0.05) and soleus EMG (P > 0.05) recorded on the floor increased after tenotomy of synergists. Furthermore, the afferent input was inhibited when the soleus EMG disappeared after tenotomy of soleus. The afferent neurogram and EMG of the soleus showed correlated responses to a variety of treatments, suggesting that the afferent neurogram recorded at the L(5) segmental level reflects the neural input associated with the activity level of the soleus predominantly. The level of efferent neurogram decreased after acute hindlimb suspension but was not influenced significantly by tenotomy of synergists and/or soleus itself. The EMG and afferent neurograms remained low up to the 4th day but recovered to the preexperimental levels within 14 days, due to reorganization of sarcomere number and length, as well as the shortening of muscle fiber length and recovery of tension development. It is suggested that the levels of EMG and afferent neurogram associated with antigravity muscle are closely related to the tension development of the muscle.

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Section: Acute Responses Of Neuromuscular Activitiesmentioning

confidence: 87%

Section: Acute Responses Of Neuromuscular Activitiesmentioning

confidence: 99%

Tension- and afferent input-associated responses of neuromuscular system of rats to hindlimb unloading and/or tenotomy

Kawano¹,

Ishihara²,

Stevens³

et al. 2004

American Journal of Physiology-Regulatory, Integrative and Comp

122

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“…Hind limb unloading was performed as described by Morey (1979). Tenotomy was induced by cutting the Achilles tendon bilaterally (Ohara et al . 1996, Yoshinaga et al .…”

Section: Methodsmentioning

confidence: 99%

“…1987). Tenotomy results in a further decrease in the loading of these muscles by eliminating active and passive stretch (Ohara et al . 1996).…”

mentioning

confidence: 99%

Expression of heat shock protein 72 in atrophied rat skeletal muscles

Oishi

Ishihara

Talmadge

et al. 2001

Acta Physiologica Scandinavica

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Changes in the expression of heat shock protein 72 (HSP72) in response to atrophic-inducing perturbations of muscle involving chronic mechanical unloading and denervation were determined. Adult male Wistar rats were assigned randomly to a sedentary cage control (CON), hind limb unloading (HU, via tail suspension), HU plus tenotomy (HU + TEN), HU plus denervation (HU + DEN), or HU + TEN + DEN group. Tenotomy and DEN involved cutting the Achilles tendon and removing a segment of the sciatic nerve, respectively. After 5 days, HSP72 levels in the soleus of the HU + DEN and HU + TEN + DEN groups were 42 (P < 0.05) and 53% (P < 0.01) less than CON, respectively. Soleus weight decreased in both groups. Heat shock protein 72 levels in the plantaris of the HU + TEN, HU + DEN, and HU + TEN + DEN groups were 31, 25, and 30% lower than CON, respectively (P < 0.05). Plantaris weight decreased in the HU + DEN and HU + TEN + DEN, but not in the HU + TEN group. Hind limb unloading alone had little effect on the HSP72 level in either muscle. Reduced levels of HSP72 were associated with a decreased soleus (r=0.62, P < 0.01) and plantaris (r=0.78, P < 0.001) weight. These results indicate that the levels of HSP72 in both a slow and a fast rat plantarflexor are responsive to a chronic decrease in the levels of loading and/or activation and suggest that the neuromuscular activity level and the presence of innervation of a muscle are important factors that induce HSP72 expression.

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“…Suspensionrelated decrease of soleus weight was not promoted by addition of tenotomy, denervation, or both ( table 1 ) [Ohara et al, 1996]. And that of plantaris was gradually increased as HU-C !…”

Section: Muscle Fiber Csa Adaptationsmentioning

confidence: 98%

The Role of Neural and Mechanical Influences in Maintaining Normal Fast and Slow Muscle Properties

Ohira

Yoshinaga

Ohara

et al. 2006

Cells Tissues Organs

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The relative importance of neural and mechanical influences in maintaining normal slow and fast muscle properties remains unclear. To address this issue, we studied the effects of 10 days of hindlimb unloading (HU) with or without tenotomy and/or denervation on the cross-sectional area (CSA), myosin heavy chain (MHC) expression (immunohistochemistry) and composition (gel electrophoresis), and myonuclear number in soleus and plantaris fibers in adult male Wistar rats. In general, the adaptations in fiber type and size were similar using either single fiber gel or immunohistochemical analyses. HU resulted in atrophy of type I and I+IIa/x MHC fibers in the soleus and in type I, I+IIa/x, IIa/x, IIa/x+IIb, and IIb MHC fibers in the plantaris. Addition of tenotomy and/or denervation in HU rats had minimal effects on fiber CSA in the soleus, but fiber CSA in the plantaris further decreased, particularly in fibers expressing only fast MHCs. HU resulted in a de novo appearance of type I+IIa/x+IIb and IIa/x+IIb MHC fibers in the soleus and of type I+IIa/x+IIb MHC fibers in the plantaris.Tenotomy and/or denervation in HU rats had no further effect on the fiber type composition of either muscle. Mean myonuclear number/mm of type I fibers was decreased in the soleus of HU rats, and increased in type I and I+IIa/x fibers in HU plus tenotomy (HU+Ten) rats. In the plantaris, mean myonuclear number/mm of type IIa/x, IIa/x+IIb, and IIb fibers was lower after HU with or without tenotomy and/or denervation. Mean cytoplasmic volume/myonucleus ratio of type I and I+IIa/x fibers in the soleus of the HU group tended to be smaller than in controls. The largest decrease was noted in the HU+Ten group. In the plantaris, this ratio was unaffected by HU alone, but was decreased by addition of tenotomy and/or denervation when all fiber types were combined. These data indicate that the major cause of fiber atrophy and adaptations in myonuclear domain size in the slow soleus of HU rats is the chronic reduction in force generation, whereas the elimination of neuromuscular contact via denervation results in additional fiber atrophy and adaptations in myonuclear domain size in the fast plantaris.

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Responses of ankle plantar-flexors to various inhibitions of muscular activities in rats.

Cited by 5 publications

References 11 publications

Tension- and afferent input-associated responses of neuromuscular system of rats to hindlimb unloading and/or tenotomy

Tension- and afferent input-associated responses of neuromuscular system of rats to hindlimb unloading and/or tenotomy

Expression of heat shock protein 72 in atrophied rat skeletal muscles

The Role of Neural and Mechanical Influences in Maintaining Normal Fast and Slow Muscle Properties

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