Neuromuscular Adaptations to Actual and Simulated Spaceflight

Edgerton, V. Reggie; Roy, Roland R.

doi:10.1002/cphy.cp040132

Cited by 75 publications

(106 citation statements)

References 180 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This direction of change is consistent with the results of previous short-term HU studies [Thomason and Booth, 1990;Edgerton and Roy, 1996;Stevens et al, 2004]. The addition of tenotomy and/or denervation in HU rats had no additional effect on the fiber phenotype, except for a significant increase in pure type II fibers in the soleus in both denervation groups ( fig.…”

Section: Muscle Fiber Phenotype Adaptationssupporting

confidence: 91%

“…The decreases in fiber size in HU rats were consistent with previous short-term HU studies [Roy et al, 1991;Edgerton and Roy, 1996;Ohira et al, 1997]. In addition, the relatively larger decreases in the pure type I fibers in the soleus and the pure type IIb fibers in the plantaris are consistent with the atrophic effect being more prominent in the predominant fiber type within a muscle [Roy et al, 1991].…”

Section: Muscle Fiber Csa Adaptationssupporting

confidence: 88%

“…When unloaded muscles were denervated (resulting in inactivity and the loss of activity-independent neural influences) during the period of rapid atrophy, i.e. the first 2 weeks of HU [Thomason and Booth, 1990;Edgerton and Roy, 1996], there was an additional effect on the reduction of fiber size in the plantaris, but not the soleus muscle, reflecting the stronger neural influence on fast than slow muscles.…”

Section: Role Of Neuromuscular Activity In Maintaining Muscle Propertiesmentioning

confidence: 99%

“…muscles composed predominantly of slow fibers [Thomason et al, 1987;Caiozzo et al, 1994;Ohira and Edgerton, 1994;Allen et al, 1996;Edgerton and Roy, 1996;Ohira, 2000;Ohira et al, 2002]. Pronounced atrophy and shift towards a faster fiber phenotype, particularly in the slow soleus muscle, has been a consistent finding in response to chronic hindlimb unloading (HU).…”

mentioning

confidence: 99%

See 3 more Smart Citations

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

Ohira

Yoshinaga

Ohara

et al. 2006

Cells Tissues Organs

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Muscle Fiber Phenotype Adaptationssupporting

confidence: 91%

Section: Muscle Fiber Csa Adaptationssupporting

confidence: 88%

Section: Role Of Neuromuscular Activity In Maintaining Muscle Propertiesmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

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

Ohira

Yoshinaga

Ohara

et al. 2006

Cells Tissues Organs

Self Cite

View full text Add to dashboard Cite

show abstract

“…The adductor longus of the rat, a predomi-nantly slow adductor of the thigh, provides a means of testing whether plasticity observed in the soleus can be attributed to the ''slowness'' of the muscle or to some other properties unique to this muscle. As in the soleus, the adductor longus atrophies markedly following short periods of space flight (D'Amelio and Daunton, 1992;Martin et al, 1988;Riley et al, 1992) or hindlimb suspension (Grindeland et al, 1994;Riley et al, 1992), two experimental models of chronic unloading (Edgerton and Roy, 1996;Roy et al, 1991a). Following 8 weeks of a moderately intense weight-lifting program (Ho et al, 1980), the adductor longus was reported to hypertrophy (14%) and show signs of fiber splitting and to show an increase in the number of fibers per unit crosssectional area.…”

mentioning

confidence: 99%