Recovery from central core degeneration of the tenotomized rat soleus muscle

Baker, James H.; Hall-Craggs, E. C. B.

doi:10.1002/mus.880030208

Cited by 35 publications

(21 citation statements)

References 10 publications

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“…All animals were kept under the same environmental conditions. For tenotomy, animals were intraperitoneally anesthetized with sodium pentobarbital (45 mg/kg) and both proximal and distal tendons of the soleus were transected (BAKER and HALL-CRAGGS, 1980) with standard antiseptic precautions. Through a small posterio-lateral skin incision at the knee, the proximal tendon of the soleus was cut with a scalpel while the lateral head of the gastrocnemius was pulled medially.…”

Section: Animalsmentioning

confidence: 99%

“…In the tenotomized rat soleus, muscle fibers undergo a series of ultrastructural changes. These become most extensive between 5 and 10 days postoperative, followed by a process of recovery (KARPATI et al, 1972;BAKER and HALL-CRAGGS, 1980). Our previous work on the myotendinous junction of tenotomized soleus muscles demonstrated the characteristic retraction of sarcoplasmic processes coupled with the myofibrillar disintegration basically similar to the central core lesion at the middle part of muscle (ABou SALEM et al, 1993).…”

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confidence: 95%

“…Experimental tendon transection of the soleus muscle has drawn the attention of many muscle researchers because of the unique pattern of myofibrillar degeneration in the muscle fibers (MCMINN and VERBOVA, 1962;ENGEL et al, 1966;RESNICK et al, 1968;SHAFIQ et al, 1969;KARPATI et al, 1972;BAKER and HALL-CRAGGS, 1980;MCLACHLAN, 1983;WROBLEWSKI and EDSTROM, 1983 ;JOZSA et al, 1988;BAKER and POINDEXToR,1991). As such degenerative changes resemble some of myofibrillar alterations seen in certain myopathies of the human, the tenotomized muscles have come to be studied as an experimental model of human myopathies.…”

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confidence: 99%

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Scanning Electron Microscopy of Tenotomized Soleus Muscles of the Rat.

Salem

Saito

Ishikawa

1993

Archives of Histology and Cytology

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Summary. The effects of tenotomy on the surface morphology of muscle fibers including myotendinous junctions in the rat soleus muscle were studied by scanning electron microscopy (SEM). Using potassium hydroxide (KOH) and collagenase, the extracellular materials were successfully removed to expose the surface of muscle fibers. When the soleus muscle was tenotomized at both proximal and distal ends, virtually all muscle fibers showed marked alterations of the fiber surface characterized by the formation of numerous transverse grooves and folds along their length. Narrow longitudinal grooves and folds of the sarcolemma were also observed. At myotendinous junctions, the fiber ends showed an overall rounded shape with several short sarcoplasmic processes, indicating that the processes were significantly retracted. These changes were clearly recognizable at 5 days after tenotomy, and most apparent at one week. Thin-section electron microscopy of the same SEM samples demonstrated that such folding of the sarcolemma was not directly related to the sarcomere pattern of the underlying myofibrils, suggesting that, once formed, the folds and grooves were retained for a certain period of time. At 2 and 3 weeks the surface morphology of the fibers underwent a recovery process of restoring the smooth surface on which the crossstriations of the underlying myofibrils were seen. At the fiber ends, sarcoplasmic processes regrew into slender, wavy and short forms. Such sarcoplasmic processes were greater in number and more elaborate than those in the control muscle. At 5 and 6 weeks the fiber surface resumed an almost normal morphology, except that the sarcoplasmic processes at the fiber end were still shorter and more numerous than those in the control. These observations support our previous results obtained by thin-section electron microscopy that the myotendinous junction undergoes a series of morphological changes of collapse and regrowth of the sarcoplasmic processes, reflecting changes in the underlying myofibrils. In conclusion, the changes in the surface morphology of tenotomized muscle fibers were well correlated chronologically to those of myofibrils such as the central core lesion.

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Section: Animalsmentioning

confidence: 99%

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confidence: 95%

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confidence: 99%

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Scanning Electron Microscopy of Tenotomized Soleus Muscles of the Rat.

Salem

Saito

Ishikawa

1993

Archives of Histology and Cytology

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“…The elastic bands provided resistance, albeit small, and these loaded contractions may have contributed to prevention of lesions. CCLs occur in other conditions of chronic shortening, such as tenotomy and immobilization by casting in a shortened position (4,8,19). The degeneration of myofibrils after tenotomy correlates with the hypershortened state of the sarcomeres (3).…”

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confidence: 99%

Passive stretch inhibits central corelike lesion formation in the soleus muscles of hindlimb-suspended unloaded rats

Baewer

Hoffman²,

Romatowski³

et al. 2004

Journal of Applied Physiology

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. Passive stretch inhibits central corelike lesion formation in the soleus muscles of hindlimb-suspended unloaded rats. J Appl Physiol 97: 930 -934, 2004. First published May 7, 2004 10.1152/japplphysiol.00103.2004.-Hindlimb suspension unloading (HSU) is a ground-based model simulating the effects of microgravity unloading on the musculoskeletal system. In this model, gravity causes the hind foot of the rat to drop, opening the front of the ankle to 90 -105°plantar flexion at rest. As HSU proceeds, the normal weight-bearing angle of 30°dorsiflexion is achieved progressively less, and the contraction range of soleus is abbreviated. Our laboratory reported that 12 days of HSU caused central corelike lesions (CCLs) of myofibril breakdown (Riley DA, Slocum GR, Bain JL, Sedlak FR, Sowa TE, and Mellender JW. J Appl Physiol. 69: 58 -66, 1990). The present study investigated whether daily stretch of the calf muscles prevents CCL formation. The soleus muscles of HSU SpragueDawley male rats (ϳ287 g) were lengthened by unilateral ankle splinting at 30°. Compared with the nonsplinted side, splinting for 10 or 20 min per day in awake rats significantly decreased CCLs in soleus by 88 and 91%, respectively (P Ͻ 0.01). Compared with control muscle wet weight, 20-min splinting reduced atrophy by 33%, whereas 10-min splinting ameliorated atrophy by 17% (P Ͻ 0.01). Bilateral soleus electromyograph recording revealed higher levels of contractile activity on the splinted side during splinting. To isolate the effects of stretch from isometric contractile activity, contractions were eliminated by whole animal anesthesia with isoflurane during 10-min daily splinting. The percentage of fibers with CCLs was reduced by 57%, and the average lesion size was 29% smaller in the stretched muscle (P Ͻ 0.05). Soleus muscle wet weight and fiber area were unaltered by stretch alone. Loaded contractions during splinting are necessary to prevent muscle fiber atrophy. Passive muscle stretch acts to maintain myofibril structural integrity. length; countermeasure; splint; atrophy; calcium HINDLIMB SUSPENSION UNLOADING (HSU) of rats is a well-established experimental model for simulating the effects of microgravity unloading on weight-bearing muscles (25). Preventing rats from touching the ground with their hindlimbs causes the antigravity soleus muscles to atrophy due to decreased use, unloading, and shortened working range (29). Central corelike lesions (CCLs), which are areas of focal myofibril dissolution, appear within soleus fibers by day 12 of HSU. For rat solei, the CCLs were postulated to result from the ϳ20% shortened contraction range, which is a consequence of suspensioninduced foot drop posture (plantar flexion) (22,29). Foot drop posture of humans floating in microgravity was first documented in their neutral body position during Skylab missions (26). CCLs also occur in suspension-unloaded rabbits in which soleus shortening is ϳ35% because the large hind feet are weighed down by gravity (2). A shortened length is required for CCL generati...

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“…Myofibrillar remodeling restores the initially kinked sarcomeres to normal length by approximately 4 to 6 weeks with a reduction in sarcomere number to accommodate the new muscle position and restore optimal length for active force production. 34,44 The muscle shortening that accompanies fascial separation and hernia formation requires sarcomere remodeling to adapt to the new position. During repair, significant tension was required to reapproximate the fascial edges and restore the abdominal wall muscles to their preoperative positions.…”

Section: Discussionmentioning

confidence: 99%

Reversibility of Abdominal Wall Atrophy and Fibrosis After Primary or Mesh Herniorrhaphy

et al. 2013

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Objective To determine whether primary or mesh herniorrhaphy reverses abdominal wall atrophy and fibrosis associated with hernia formation. Background We previously demonstrated that hernia formation is associated with abdominal wall atrophy and fibrosis after 5 weeks in an animal model. Methods Arat model of chronic incisional hernia was used. Groups consisted of uninjured control (UC, n = 8), sham repair (SR, n = 8), unrepaired hernia (UR, n = 8), and 2 repair groups: primary repair (PR, n = 8) or tension-free polypropylene mesh repair (MR, n = 8) hernia repair on postoperative day (POD) 35. All rats were killed on POD 70. Intact abdominal wall strips were cut perpendicular to the wound for tensiometric analysis. Internal oblique muscles were harvested for fiber type and size determination. Results No hernia recurrences occurred after PR or MR. Unrepaired abdominal walls significantly demonstrated greater stiffness, increased breaking and tensile strengths, yield load and yield energy, a shift to increased type IIa muscle fibers than SR (15.9% vs 9.13%; P < 0.001), and smaller fiber cross-sectional area (CSA, 1792 vs 2669 μm2; P < 0.001). PR failed to reverse any mechanical changes but partially restored type IIa fiber (12.9% vs 9.13% SR; P < 0.001 vs 15.9% UR; P < 0.01) and CSA (2354 vs 2669 μm2 SR;P < 0.001 vs 1792 μm2 UR; P < 0.001). Mesh-repaired abdominal walls demonstrated a trend toward an intermediate mechanical phenotype but fully restored type IIa muscle fiber (9.19% vs 9.13% SR; P > 0.05 vs 15.9% UR; P < 0.001) and nearly restored CSA (2530 vs 2669 μm2 SR; P < 0.05 vs 1792 μm2 UR; P < 0.001). Conclusions Mesh herniorrhaphy more completely reverses atrophic abdominal wall changes than primary herniorrhaphy, despite failing to restore normal anatomic muscle position. Techniques for hernia repair and mesh design should take into account abdominal wall muscle length and tension relationships and total abdominal wall compliance.

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Recovery from central core degeneration of the tenotomized rat soleus muscle

Cited by 35 publications

References 10 publications

Scanning Electron Microscopy of Tenotomized Soleus Muscles of the Rat.

Scanning Electron Microscopy of Tenotomized Soleus Muscles of the Rat.

Passive stretch inhibits central corelike lesion formation in the soleus muscles of hindlimb-suspended unloaded rats

Reversibility of Abdominal Wall Atrophy and Fibrosis After Primary or Mesh Herniorrhaphy

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