Effect of hindlimb unloading on resting intracellular calcium in intrafusal fibers and ramp-and-hold stretches evoked responsiveness of soleus muscle spindles in conscious rats

2008 ◽  
Vol 442 (3) ◽  
pp. 169-173 ◽  
Author(s):  
Yongjin Zhu ◽  
Xiaoli Fan ◽  
Xiaohui Li ◽  
Sudi Wu ◽  
Hongmei Zhang ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Soleus Muscle ◽  
Muscle Spindles ◽  
Hindlimb Unloading ◽  
Conscious Rats ◽  
Intrafusal Fibers

scholarly journals Expression of Myosin Heavy Chain Isoforms Along Intrafusal Fibers of Rat Soleus Muscle Spindles After 14 Days of Hindlimb Unloading

2002 ◽  
Vol 50 (11) ◽  
pp. 1543-1553 ◽  
Author(s):  
L. De-Doncker ◽  
F. Picquet ◽  
G. Butler Browne ◽  
M. Falempin
Keyword(s):  
Soleus Muscle ◽  
Muscle Spindles ◽  
Myosin Heavy Chain Isoforms ◽  
Hindlimb Unloading ◽  
Cross Sectional ◽  
Intrafusal Fibers ◽  
Significant Difference ◽  
Slow Type ◽  
Rat Soleus Muscle

Morphological, contractile, histochemical, and electrophoretical characteristics of slow postural muscles are altered after hindlimb unloading (HU). However, very few data on intrafusal fibers (IFs) are available. Our aim was to determine the effects of 14 days of hindlimb unloading on the morphological and immunohistochemical characteristics of IF in rat soleus muscle. Thirty-three control and 32 unloaded spindles were analyzed. The number and distribution of muscle spindles did not appear to be affected after unloading. There was no significant difference in number, cross-sectional area, and histochemical properties of IF between the two groups. However, after unloading, a significant decrease in slow type 1 MHC isoform and a slight increase in slow-tonic MHC expression were observed in the B and C regions of the bag1 fibers. The α-cardiac MHC expression was significantly decreased along the entire length of the bag2 fibers and in the B and C regions of the bag1 fibers. In 12 muscle spindles, the chain fibers expressed the slow type 1 and α-cardiac MHC isoforms over a short distance of the A region, although these isoforms are not normally expressed. The most striking finding of the study was the relative resistance of muscle spindles to perturbation induced by HU.

Muscle regeneration during hindlimb unloading results in a reduction in muscle size after reloading

2001 ◽  
Vol 91 (1) ◽  
pp. 183-190 ◽  
Author(s):  
P. E. Mozdziak ◽  
P. M. Pulvermacher ◽  
E. Schultz
Keyword(s):  
Mitotic Activity ◽  
Satellite Cell ◽  
Soleus Muscle ◽  
Weight Bearing ◽  
Weight Ratio ◽  
The Body ◽  
Hindlimb Unloading ◽  
Muscle Size ◽  
Unit Size ◽  
Muscle Weight

The hindlimb-unloading model was used to study the ability of muscle injured in a weightless environment to recover after reloading. Satellite cell mitotic activity and DNA unit size were determined in injured and intact soleus muscles from hindlimb-unloaded and age-matched weight-bearing rats at the conclusion of 28 days of hindlimb unloading, 2 wk after reloading, and 9 wk after reloading. The body weights of hindlimb-unloaded rats were significantly ( P < 0.05) less than those of weight-bearing rats at the conclusion of hindlimb unloading, but they were the same ( P > 0.05) as those of weight-bearing rats 2 and 9 wk after reloading. The soleus muscle weight, soleus muscle weight-to-body weight ratio, myofiber diameter, number of nuclei per millimeter, and DNA unit size were significantly ( P< 0.05) smaller for the injured soleus muscles from hindlimb-unloaded rats than for the soleus muscles from weight-bearing rats at each recovery time. Satellite cell mitotic activity was significantly ( P < 0.05) higher in the injured soleus muscles from hindlimb-unloaded rats than from weight-bearing rats 2 wk after reloading, but it was the same ( P > 0.05) as in the injured soleus muscles from weight-bearing rats 9 wk after reloading. The injured soleus muscles from hindlimb-unloaded rats failed to achieve weight-bearing muscle size 9 wk after reloading, because incomplete compensation for the decrease in myonuclear accretion and DNA unit size expansion occurred during the unloading period.

scholarly journals Activity of mu- and m-calpain in regenerating fast and slow twitch skeletal muscles.

1996 ◽  
Vol 43 (4) ◽  
pp. 693-700 ◽  
Author(s):  
J Moraczewski ◽  
E Piekarska ◽  
M Zimowska ◽  
M Sobolewska
Keyword(s):  
Intracellular Calcium ◽  
Soleus Muscle ◽  
Muscle Regeneration ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Slow Twitch ◽  
Edl Muscle ◽  
Calpain Ii ◽  
Complete Regeneration

Calpains--non-lysosomal intracellular calcium-activated neutral proteinases, form a family consisting of several distinct members. Two of the isoenzymes: mu (calpain I) and m (calpain II) responded differently to the injury during complete regeneration of Extensor digitorum longus (EDL) muscle and partial regeneration of Soleus muscle. In the crushed EDL the level of m-calpain on the 3rd and 7th day of regeneration was higher than in non-operated muscles, whereas the activity of this calpain in injured Soleus decreased. The level of mu-calpain in EDL oscillated irregularly during regeneration whereas in Soleus of both injured and contralateral muscles its level rapidly rose. Our results support the hypothesis that m-calpain is involved in the process of fusion of myogenic cells whereas mu-calpain plays a significant but indirect role in muscle regeneration.

Mechanical stimulation of the plantar foot surface attenuates soleus muscle atrophy induced by hindlimb unloading in rats

2005 ◽  
Vol 99 (2) ◽  
pp. 739-746 ◽  
Author(s):  
Antonios Kyparos ◽  
Daniel L. Feeback ◽  
Charles S. Layne ◽  
Daniel A. Martinez ◽  
Mark S. F. Clarke
Keyword(s):  
Muscle Atrophy ◽  
Soleus Muscle ◽  
Gastrocnemius Muscle ◽  
Hindlimb Unloading ◽  
Medial Gastrocnemius ◽  
Type I ◽  
Cross Sectional ◽  
Plantar Surface ◽  
Male Wistar Rats ◽  
Medial Gastrocnemius Muscle

Unloading-induced muscle atrophy occurs in the aging population, bed-ridden patients, and astronauts. This study was designed to determine whether dynamic foot stimulation (DFS) applied to the plantar surface of the rat foot can serve as a countermeasure to soleus muscle atrophy normally observed in hindlimb unloaded (HU) rats. Forty-four mature (6 mo old), male Wistar rats were randomly assigned to ambulatory control, HU alone, HU with active DFS (i.e., plantar contact with active inflation), HU with passive DFS (i.e., plantar contact without active inflation), and HU while wearing a DFS boot with no plantar contact groups. Application of active DFS during HU significantly counteracted the atrophic response by preventing ∼85% of the reduction in type I myofiber cross-sectional area (CSA) in the soleus while preventing ∼57% of the reduction in type I myofiber CSA and 43% of the reduction in type IIA myofiber CSA of the medial gastrocnemius muscle. Wearing of a DFS boot without active inflation prevented myofiber atrophy in the soleus of HU animals in a fashion similar to that observed in HU animals that wore an actively inflated DFS boot. However, when a DFS boot without plantar surface contact was worn during HU, no significant protection from HU-induced myofiber atrophy was observed. These results illustrate that the application of mechanical foot stimulation to the plantar surface of the rat foot is an effective countermeasure to muscle atrophy induced by HU.

scholarly journals Muscle Spindles in the Deep Muscles of the Human Neck: A Morphological and Immunocytochemical Study

2003 ◽  
Vol 51 (2) ◽  
pp. 175-186 ◽  
Author(s):  
Jing-Xia Liu ◽  
Lars-Eric Thornell ◽  
Fatima Pedrosa-Domellöf
Keyword(s):  
Fiber Length ◽  
Biceps Brachii ◽  
Muscle Spindles ◽  
Functional Specialization ◽  
Immunocytochemical Study ◽  
Intrafusal Fibers ◽  
Myhc Isoforms ◽  
Nuclear Chain ◽  
Human Muscles ◽  
Lumbrical Muscles

Muscle spindle density is extremely high in the deep muscles of the human neck. However, there is a paucity of information regarding the morphology and immunoreactivity of these muscle spindles. The objective of this study was to investigate the intrafusal fiber content and to assess the myosin heavy chain (MyHC) composition of muscle spindles from human deep neck muscles. In addition to the conventional spindles containing bag1, bag2, and chain fibers (b1b2c spindle), we observed a number of spindles lacking bag1 (b2c spindle) or bag2 (b1c spindle) fibers. Both bag1 and bag2 fibers contained slow tonic MyHCs along their entire fiber length and MyHCI, MyHCIIa, embryonic, and α-cardiac MyHC isoforms along a variable length of the fibers. Fetal MyHC was present in bag2 fibers but not in bag1 fibers. Nuclear chain fibers contained MyHCIIa, embryonic, and fetal isoforms with regional variations. We also compared the present data with our previous results obtained from muscle spindles in human biceps brachii and the first lumbrical muscles. The allotment of numbers of intrafusal fibers and the MyHC composition showed some muscle-related differences, suggesting functional specialization in the control of movement among different human muscles.

Structural and functional remodeling of skeletal muscle microvasculature is induced by simulated microgravity

2000 ◽  
Vol 278 (6) ◽  
pp. H1866-H1873 ◽  
Author(s):  
Michael D. Delp ◽  
Patrick N. Colleran ◽  
M. Keith Wilkerson ◽  
Matthew R. McCurdy ◽  
Judy Muller-Delp
Keyword(s):  
Skeletal Muscle ◽  
Soleus Muscle ◽  
Skeletal Muscles ◽  
Gastrocnemius Muscle ◽  
Fluid Pressure ◽  
Hindlimb Unloading ◽  
Cross Sectional ◽  
Luminal Diameter ◽  
Structural Remodeling

Hindlimb unloading of rats results in a diminished ability of skeletal muscle arterioles to constrict in vitro and elevate vascular resistance in vivo. The purpose of the present study was to determine whether alterations in the mechanical environment (i.e., reduced fluid pressure and blood flow) of the vasculature in hindlimb skeletal muscles from 2-wk hindlimb-unloaded (HU) rats induces a structural remodeling of arterial microvessels that may account for these observations. Transverse cross sections were used to determine media cross-sectional area (CSA), wall thickness, outer perimeter, number of media nuclei, and vessel luminal diameter of feed arteries and first-order (1A) arterioles from soleus and the superficial portion of gastrocnemius muscles. Endothelium-dependent dilation (ACh) was also determined. Media CSA of resistance arteries was diminished by hindlimb unloading as a result of decreased media thickness (gastrocnemius muscle) or reduced vessel diameter (soleus muscle). ACh-induced dilation was diminished by 2 wk of hindlimb unloading in soleus 1A arterioles, but not in gastrocnemius 1A arterioles. These results indicate that structural remodeling and functional adaptations of the arterial microvasculature occur in skeletal muscles of the HU rat; the data suggest that these alterations may be induced by reductions in transmural pressure (gastrocnemius muscle) and wall shear stress (soleus muscle).

scholarly journals Sex differences in forkhead box O3a signaling response to hindlimb unloading in rat soleus muscle

2018 ◽  
Vol 69 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Toshinori Yoshihara ◽  
Toshiharu Natsume ◽  
Takamasa Tsuzuki ◽  
Shuo-wen Chang ◽  
Ryo Kakigi ◽  
...  
Keyword(s):  
Sex Differences ◽  
Soleus Muscle ◽  
Hindlimb Unloading ◽  
Forkhead Box ◽  
Rat Soleus Muscle ◽  
Forkhead Box O3a
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