Reflex and muscular adaptations in rat soleus muscle after hindlimb suspension

1999 ◽  
Vol 202 (19) ◽  
pp. 2701-2707 ◽  
Author(s):  
J. Anderson ◽  
M.I. Almeida-Silveira ◽  
C. Perot
Keyword(s):  
Soleus Muscle ◽  
Muscle Spindles ◽  
H Reflex ◽  
Hindlimb Suspension ◽  
Type I ◽  
Shortening Velocity ◽  
Fibre Type Composition ◽  
Reflex Responses ◽  
In Series ◽  
T Reflex

Reflex, mechanical and histochemical adaptations of the soleus muscle following 3 weeks of hindlimb suspension (HS) were measured in the rat. HS transformed the soleus muscle fibre type composition from predominantly slow, type I, to approximately equal proportions of fast, type II and slow fibres. Consistent with this transformation was an increase in the maximum shortening velocity, V(max), and a decrease in the stiffness of the series elastic component. Disuse also produced muscle atrophy and a resultant decrease in twitch and tetanic force. Reflex responses of the ankle extensors were also obtained at 5 and 9 weeks of age for six control rats (C group) and six rats subjected to HS for 3 weeks (HS group). The soleus reflexes to a mechanical tap applied to the Achilles tendon (T reflex) and to an electrical stimulation of the sciatic nerve (H reflex) were measured. The maximal amplitude of these reflexes (T(max) and H(max)) were normalised to the maximal direct motor response (M(max)) and the T(max)/H(max) ratio was also calculated to give an index of the relative adaptations of the peripheral and central components of the reflex pathway. The HS group showed significantly higher H reflex gains than the C group, possibly due to changes in synaptic efficiency after HS. Conversely, the HS group presented strongly inhibited T reflexes and negative gains for the T(max)/H(max) ratios. This result indicated a reduced spindle solicitation after HS, which may reflect changes in the spindle sensitivity itself, but it could also be due to the decrease in stiffness of the musculo-tendinous elements in series with the muscle spindles. Such mechanical changes may play an important part in the decreased T reflex responses.

TGF-β1 and TNF-α are involved in the transcription of type I collagen α2 gene in soleus muscle atrophied by mechanical unloading

2008 ◽  
Vol 104 (1) ◽  
pp. 170-177 ◽  
Author(s):  
Tatsuro Hirose ◽  
Koichi Nakazato ◽  
Hongsun Song ◽  
Naokata Ishii
Keyword(s):  
Soleus Muscle ◽  
Type I Collagen ◽  
Control Level ◽  
Muscle Spindles ◽  
Hindlimb Suspension ◽  
Type I ◽  
Regulatory Factors ◽  
Tnf Α ◽  
Male Wistar Rats ◽  
Connective Tissue Sheath

The aim of this study was to examine the effect of hindlimb suspension (HS) on the expressions of COL1A2 (type I collagen α2 chain) mRNA and its regulatory factors, transforming growth factors (TGF)-β1, -β2, and -β3, phosphorylated Smad3, and tumor necrosis factor-α (TNF-α) in rat hindlimb muscles. Forty-eight male Wistar rats (age, 5 wk) were randomly assigned to HS for 1, 3, 7, and 14 days and control ( n = 6 for each). During the exposure to HS, COL1A2 mRNA expression decreased in the soleus muscle at day 3 and recovered to control level at day 7. The content of TNF-α, one of the negative regulatory factors for COL1A2, increased from day 3 until day 14. On the other hand, the contents of TGF-β1, TGF-β3, and Smad3, positive regulatory factors for COL1A2, increased at day 7. The in situ hybridization for COL1A2 and the immunohistochemistry of TGF-β1 and TNF-α revealed their expressions around nerve-related tissues, including muscle spindles and connective tissue sheath. The results indicate that the transcriptional activity of COL1A2 in the soleus muscle initially decreases in response to unloading through an increase in TNF-α production; thereafter, it returns toward normal level through the activated TGF-β/Smad pathway.

Distribution of myosin heavy chain isoforms in non-weight-bearing rat soleus muscle fibers

1996 ◽  
Vol 81 (6) ◽  
pp. 2540-2546 ◽  
Author(s):  
Robert J. Talmadge ◽  
Roland R. Roy ◽  
V. Reggie Edgerton
Keyword(s):  
Myosin Heavy Chain ◽  
Soleus Muscle ◽  
Heavy Chain ◽  
De Novo ◽  
Weight Bearing ◽  
Muscle Fibers ◽  
Myosin Heavy Chain Isoforms ◽  
Hindlimb Suspension ◽  
Type I ◽  
Rat Soleus Muscle

Talmadge, Robert J., Roland R. Roy, and V. Reggie Edgerton.Distribution of myosin heavy chain isoforms in non-weight-bearing rat soleus muscle fibers. J. Appl. Physiol. 81(6): 2540–2546, 1996.—The effects of 14 days of spaceflight (SF) or hindlimb suspension (HS) (Cosmos 2044) on myosin heavy chain (MHC) isoform content of the rat soleus muscle and single muscle fibers were determined. On the basis of electrophoretic analyses, there was a de novo synthesis of type IIx MHC but no change in either type I or IIa MHC isoform proportions after either SF or HS compared with controls. The percentage of fibers containing only type I MHC decreased by 26 and 23%, and the percentage of fibers with multiple MHCs increased from 6% in controls to 32% in HS and 34% in SF rats. Type IIx MHC was always found in combination with another MHC or combination of MHCs; i.e., no fibers contained type IIx MHC exclusively. These data suggest that the expression of the normal complement of MHC isoforms in the adult rat soleus muscle is dependent, in part, on normal weight bearing and that the absence of weight bearing induces a shift toward type IIx MHC protein expression in the preexisting type I and IIa fibers of the soleus.

beta-MHC transgene expression in suspended and mechanically overloaded/suspended soleus muscle of transgenic mice

1997 ◽  
Vol 272 (5) ◽  
pp. R1552-R1561 ◽  
Author(s):  
J. J. McCarthy ◽  
A. M. Fox ◽  
G. L. Tsika ◽  
L. Gao ◽  
R. W. Tsika
Keyword(s):  
Transgenic Mice ◽  
Soleus Muscle ◽  
Transgene Expression ◽  
Specific Activity ◽  
Fiber Type ◽  
Weight Bearing ◽  
Troponin C ◽  
Hindlimb Suspension ◽  
Regulatory Sequences ◽  
Type I

Non-weight-bearing (NWB) activity [space flight and hindlimb suspension (HS)] results in the loss of soleus muscle mass, a slow-to-fast fiber-type conversion, and decreased beta-myosin heavy chain (beta-MHC) protein and mRNA expression. To identify beta-MHC promoter sequences required for decreased beta-MHC expression in response to HS, we have modified an existing noninvasive hindlimb unweighting model to accommodate the use of (transgenic) mice. After 2 wk of HS, body and muscle (soleus > gastrocnemius > plantaris) weights were decreased as was the proportion of histochemically classified type I fibers in HS soleus muscle. Northern blot analysis revealed decreases in endogenous mRNA representing beta-MHC, slow myosin light chain 1 and 2, and cardiac/slow troponin C, whereas those representing skeletal troponin C, muscle creatine kinase, and glyceraldehyde-3-phosphate dehydrogenase increased. Protein extracts prepared from HS soleus (SS) muscle of mice harboring transgenes comprised of 5.6 or 0.6 kilobase of wild type (wt) mouse beta-MHC promoter (beta 5.6 wt, beta 0.6wt) and those carrying the simultaneous mutation (mut) of the MCAT, C-rich, and beta e3 subregions (beta 5.6mut3, beta 0.6mut3) revealed decreases in chloramphenicol acetyltransferase (CAT) specific activity relative to respective controls. Decreased CAT mRNA was observed for transgene beta 5.6mut3, line 85. Two weeks of the simultaneous imposition of mechanical overload (synergist ablation) and HS (MOV/HS) countermanded the loss in absolute and normalized SS weight but did not decrease beta 0.6wt transgene expression. These transgenic results demonstrate that regulatory sequences within a 600-base pair beta-MHC promoter are sufficient to direct decreased transcription of beta-MHC transgenes after 2 wk of HS.

Myosin and troponin changes in rat soleus muscle after hindlimb suspension

1993 ◽  
Vol 74 (3) ◽  
pp. 1156-1160 ◽  
Author(s):  
M. Campione ◽  
S. Ausoni ◽  
C. Y. Guezennec ◽  
S. Schiaffino
Keyword(s):  
Soleus Muscle ◽  
Troponin I ◽  
Troponin T ◽  
High Mobility ◽  
Calcium Sensitivity ◽  
Hindlimb Suspension ◽  
Type I ◽  
Maximal Velocity ◽  
Rat Soleus Muscle ◽  
Fast Twitch

We examined the myosin heavy-chain (MHC), troponin T (TnT), and troponin I (TnI) isoform composition in the rat soleus muscle after 21 days of hindlimb suspension using electrophoretic and immunoblotting analysis with specific monoclonal antibodies. The suspended soleus showed a shift in the MHC isoform distribution with a marked increase (from 1.0 to 33%) in the relative amount of type IIa and IIx MHC and a corresponding decrease in type I MHC. However, type IIb MHC, which represents a major component in fast-twitch muscles, was not detected in suspended soleus muscles. TnT and TnI isoform composition was also changed with the appearance of fast-type TnI and TnT bands. However, a high-mobility TnT band, which represents a major component in fast-twitch muscles, was not expressed in suspended soleus. These isoform transitions may be related to the increased maximal velocity of shortening and higher calcium sensitivity previously reported in the rat soleus after hindlimb suspension.

Phase-Dependent Inhibition of H-Reflexes During Walking in Humans Is Independent of Reduction in Knee Angular Velocity

1999 ◽  
Vol 82 (2) ◽  
pp. 747-753 ◽  
Author(s):  
M. Garrett ◽  
T. Kerr ◽  
B. Caulfield
Keyword(s):  
Angular Velocity ◽  
Knee Joint ◽  
Soleus Muscle ◽  
Normal Subjects ◽  
Afferent Input ◽  
H Reflex ◽  
Short Latency ◽  
Reflex Modulation ◽  
Reflex Responses ◽  
Knee Movement

The purpose of this investigation was to investigate whether reduction in impulses arising from stretch of the quadriceps by restricting rapid knee flexion in early swing would affect inhibition of the H-reflex during swing. The contribution of afferent input arising from knee angular velocity to phase-dependent modulation of short-latency responses in the soleus was studied by simultaneously measuring joint velocity and soleus H-reflex responses at midstance and midswing phases of treadmill walking in 15 normal subjects. Stimulus strength was varied so that both maximal M and H waves were identified in each subject at midswing and midstance with the knee unrestricted (UK) and with knee movement restricted (RK), using a full leg bivalved cast to immobilize the knee joint. All subjects exhibited short-latency reflex responses in the soleus muscle. The H/M ratio at midswing was significantly reduced compared with midstance under both UK and RK walking conditions ( P < 0.0001). When compared with UK walking, knee joint angular velocity during RK walking was significantly reduced at midswing ( P < 0.001) and midstance ( P < 0.005) compared with UK. There were, however, no significant differences in H/M ratios at midswing and midstance between UK and RK walking tests. Inhibition of the H-reflex in the soleus muscle during swing was not affected by significant reduction in knee angular velocity. These results indicate that the sensory input from changes in angular velocity at the knee does not lay the inhibitory foundation of phase-related reflex modulation in the ankle extensors during walking as suggested by Brooke and colleagues.

scholarly journals Force-velocity-power and force-pCa relationships of human soleus fibers after 17 days of bed rest

1998 ◽  
Vol 85 (5) ◽  
pp. 1949-1956 ◽  
Author(s):  
J. J. Widrick ◽  
K. M. Norenberg ◽  
J. G. Romatowski ◽  
C. A. Blaser ◽  
M. Karhanek ◽  
...  
Keyword(s):  
Peak Power ◽  
Weight Bearing ◽  
Bed Rest ◽  
Force Transducer ◽  
Hindlimb Suspension ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Adult Men ◽  
Force Velocity

Soleus muscle fibers from the rat display a reduction in peak power and Ca2+ sensitivity after hindlimb suspension. To examine human responses to non-weight bearing, we obtained soleus biopsies from eight adult men before and immediately after 17 days of bed rest (BR). Single chemically skinned fibers were mounted between a force transducer and a servo-controlled position motor and activated with maximal (isotonic properties) and/or submaximal (Ca2+ sensitivity) levels of free Ca2+. Gel electrophoresis indicated that all pre- and post-BR fibers expressed type I myosin heavy chain. Post-BR fibers obtained from one subject displayed increases in peak power and Ca2+ sensitivity. In contrast, post-BR fibers obtained from the seven remaining subjects showed an average 11% reduction in peak power ( P < 0.05), with each individual displaying a 7–27% reduction in this variable. Post-BR fibers from these subjects were smaller in diameter and produced 21% less force at the shortening velocity associated with peak power. However, the shortening velocity at peak power output was elevated 13% in the post-BR fibers, which partially compensated for their lower force. Post-BR fibers from these same seven subjects also displayed a reduced sensitivity to free Ca2+( P < 0.05). These results indicate that the reduced functional capacity of human lower limb extensor muscles after BR may be in part caused by alterations in the cross-bridge mechanisms of contraction.

scholarly journals Slow recovery of the impaired fatigue resistance in postunloading mouse soleus muscle corresponding to decreased mitochondrial function and a compensatory increase in type I slow fibers

2016 ◽  
Vol 310 (1) ◽  
pp. C27-C40 ◽  
Author(s):  
Han-Zhong Feng ◽  
Xuequn Chen ◽  
Moh H. Malek ◽  
J.-P. Jin
Keyword(s):  
Fatigue Resistance ◽  
Soleus Muscle ◽  
Mitochondrial Function ◽  
Troponin T ◽  
Contractile Force ◽  
Hindlimb Suspension ◽  
Skeletal Muscle Atrophy ◽  
Type I ◽  
Myosin Isoforms ◽  
Slow Recovery

Unloading or disuse rapidly results in skeletal muscle atrophy, switching to fast-type fibers, and decreased resistance to fatigue. The recovery process is of major importance in rehabilitation for various clinical conditions. Here we studied mouse soleus muscle during 60 days of reloading after 4 wk of hindlimb suspension. Unloading produced significant atrophy of soleus muscle with decreased contractile force and fatigue resistance, accompanied by switches of myosin isoforms from IIa to IIx and IIb and fast troponin T to more low-molecular-weight splice forms. The total mass, fiber size, and contractile force of soleus muscle recovered to control levels after 15 days of reloading. However, the fatigue resistance showed a trend of worsening during this period with significant infiltration of inflammatory cells at days 3 and 7, indicating reloading injuries that were accompanied by active regeneration with upregulations of filamin-C, αB-crystallin, and desmin. The fatigue resistance partially recovered after 30–60 days of reloading. The expression of peroxisome proliferator-activated receptor γ coactivator 1α and mitofusin-2 showed changes parallel to that of fatigue resistance after unloading and during reloading, suggesting a causal role of decreased mitochondrial function. Slow fiber contents in the soleus muscle were increased after 30–60 days of reloading to become significantly higher than the normal level, indicating a secondary adaption to compensate for the slow recovery of fatigue resistance.

Running during recovery from hindlimb suspension induces transient muscle injury

1990 ◽  
Vol 68 (2) ◽  
pp. 533-539 ◽  
Author(s):  
C. E. Kasper ◽  
T. P. White ◽  
L. C. Maxwell
Keyword(s):  
Soleus Muscle ◽  
Recovery Period ◽  
Morphological Characteristics ◽  
Cross Sectional Area ◽  
Hindlimb Suspension ◽  
Type I ◽  
Sectional Area ◽  
Cross Sectional ◽  
Female Wistar Rats ◽  
Type I Fibers

The objectives were to study morphological adaptations of soleus muscle to decreased loading induced by hindlimb suspension and the effect of run training during the subsequent recovery period. Adult female Wistar rats were kept for 28 days with hindlimbs suspended. For the next 28 days, rats were assigned to a cage-sedentary or daily running group. Compared with control soleus muscles, 28 days of hindlimb suspension reduced the mass and fiber cross-sectional area to 58 and 53% of control values, respectively, and decreased type I fibers from 92 +/- 2 to 81 +/- 2%. During recovery, clusters of damaged fibers were observed in the soleus muscle, and this observation was more pronounced in trained animals. Type IIc fibers appeared transiently during recovery, and their presence was exacerbated with training, as IIc fibers increased to approximately 20% of the total by day 14 of recovery and were no longer evident at day 28. Although muscle wet mass does not differ as a result of mode of recovery at day 14, training transiently decreased the overall fiber area compared with sedentary recovery at this point. By day 28 of recovery the morphological characteristics of soleus muscle in the trained group did not differ from control muscle, whereas in the sedentary group muscle mass and overall fiber cross-sectional area were approximately 14% less than control values.

scholarly journals Force-velocity and power characteristics of rat soleus muscle fibers after hindlimb suspension

1994 ◽  
Vol 77 (4) ◽  
pp. 1609-1616 ◽  
Author(s):  
K. S. McDonald ◽  
C. A. Blaser ◽  
R. H. Fitts
Keyword(s):  
Isometric Force ◽  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hindlimb Suspension ◽  
Type I ◽  
Shortening Velocity ◽  
Power Characteristics ◽  
Sds Page ◽  
Force Velocity

The effects of 1, 2, and 3 wk of hindlimb suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HS, small fiber bundles were isolated, placed in skinning solution, and stored at -20 degrees C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control and after 1 and 3 wk of HS, and fiber type distribution and myosin light chain stoichiometry were determined from SDS-PAGE analysis. After 1 wk of HS, percent type I fibers declined from 82 to 74%, whereas hybrid fibers increased from 10 to 18%. Percent fast type II fibers increased from 8% in control and 1 wk of HS to 26% by 3 wk of HS. Most fibers showed an increased unloaded maximal shortening velocity (Vo), but myosin heavy chain remained entirely slow type I. The mechanism for increased Vo is unknown. There was a progressive decrease in fiber diameter (14, 30, and 38%) and peak force (38, 56, and 63%) after 1, 2, and 3 wk of HS, respectively. One week of HS resulted in a shift of the force-velocity curve, and between 2 and 3 wk of HS the curve shifted further such that Vo was higher than control at all relative loads < 45% peak isometric force. Peak absolute power output of soleus fibers progressively decreased through 2 wk of HS but showed no further change at 3 wk.(ABSTRACT TRUNCATED AT 250 WORDS)

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