Morphology of long‐term denervated rat soleus muscle and the effect of chronic electrical stimulation.

Schmalbruch, Henning; Al-Amood, W. S.; Lewis, D. M.

doi:10.1113/jphysiol.1991.sp018748

Cited by 127 publications

(115 citation statements)

References 17 publications

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“…We attempted a light microscopical study of these muscles (Al-Amood & Lewis, 1989a) which suggested that loss of fibres could be prevented by stimulation. A more detailed ultrastructural examination, which is reported in the preceding paper, (Schmalbruch, Al-Amood & Lewis, 1991) showed, however, that the effects of electrical stimulation on degeneration and necrosis are more complicated than suggested by our preliminary histology.…”

Section: Introductionmentioning

confidence: 85%

“…It is possible to use the changes in tension following denervation and stimulation with the morphological data (light microscopy in 3 ,um epoxy sections: Schmalbruch et al 1991) to calculate the specific tension (force per unit cross-sectional area), and the results are set out in Table 3. As would be expected, there was a large (70-fold) reduction in mean fibre size in denervated soleus and this was accompanied by an 8-fold fall in specific tension.…”

Section: Tension and Fibre Sizementioning

confidence: 99%

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Effects of chronic electrical stimulation on contractile properties of long‐term denervated rat skeletal muscle.

Al-Amood¹,

Lewis²,

Schmalbruch³

1991

The Journal of Physiology

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SUMMARY1. The contractile properties of fast-twitch (extensor digitorum longus or EDL) and slow-twitch (soleus) muscles in the rat were followed for periods of between 4 and 10 months after denervation. The effects of chronic electrical stimulation during the last 3-8 weeks of denervation were investigated.2. The fall in tetanic tension that follows axotomy ended after about 4 months' denervation. The equilibrium tension was about 0 75 % of control tension in EDL and 0 2-0{3 % in soleus.3. The low tension in soleus was due partly to the small diameter of the muscle fibres (atrophy) and partly to their necrosis that resulted in an 8-fold fall in specific tension (the force per unit cross-sectional area). Similar but less extreme changes occurred in EDL.4. It is speculated that the final level of tension reached by unstimulated denervated muscles is an equilibrium between decrease in force due to atrophy and necrosis and increase due to regeneration. Differences between the final tension levels in soleus and EDL cannot be accounted for quantitatively by known differences in atrophy alone. Therefore, the rate of necrosis in soleus and of regeneration in EDL may be higher.5. Chronic stimulation of long-term denervated muscle increased force generation by about 7-fold in EDL and between 20 and 55 times in soleus. The final tension reached was between 4 and 5 % of normal in both muscles. Specific tension of fibres was almost completely restored by stimulation and the number of fibres was normal. The failure to recover full tension was largely due to failure to reverse denervation atrophy completely.6. Twitch contraction and relaxation times were identical in denervatedstimulated soleus and EDL. There was no evidence for dependence on duration of stimulation or tension of the muscle. The normalized maximum rate of rise of tetanic tension remained higher in EDL than soleus. MIS 900144 I S. AL-AMOOD. D. M. LEW'IS AND H. SCHMALBRUCH

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Section: Introductionmentioning

confidence: 85%

Section: Tension and Fibre Sizementioning

confidence: 99%

Effects of chronic electrical stimulation on contractile properties of long‐term denervated rat skeletal muscle.

Al-Amood¹,

Lewis²,

Schmalbruch³

1991

The Journal of Physiology

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“…16 Electrical stimulation has been shown to improve muscle ®ber structure and function. 15,17,18 In animal models, investigators have reported the deleterious e ect of denervation on postreceptor insulin action, 19 exercise-induced glucose uptake, 20 insulin receptor binding, 21,22 receptor phosphorylation, 21 and the glucose transporter protein (GLUT-4). 23 ± 25 In a recent study, 26 individuals with tetraplegia were found to have a marked reduction in whole body glucose transport that appeared to be due to a proportional reduction in muscle mass.…”

Section: Determinants Of Insulin Resistancementioning

confidence: 99%

Risk factors for atherogenesis and cardiovascular autonomic function in persons with spinal cord injury

et al. 1999

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Persons with spinal cord injury (SCI) have been recognized to have several metabolic changes that adversely impact their risk for cardiovascular disease. An increased prevalence of disorders of carbohydrate metabolism and dyslipidemia may be related predominantly to paralysis with immobilization and associated loss of lean body tissue and gain in relative adiposity. Studies have reported an increased risk of vascular disease in those with SCI. As such, an understanding of the constellation of carbohydrate and lipid changes that occur after SCI is relevant to the clinical practice of medicine in this population. Oral glucose tolerance testing and associated studiesImpaired glucose tolerance and diabetes mellitus are more prevalent in individuals with SCI than in those who are able-bodied. 1 ± 4 In most of the individuals with SCI and abnormal carbohydrate tolerance, resistance to insulin mediation of glucose uptake by peripheral tissues may be demonstrable. In the presence of insulin resistance, the normal homeostatic response to glucose challenge is increased pancreatic b-cell secretion of insulin. If the compensatory response of the pancreas is insu cient to control the serum glucose concentration, worsening of carbohydrate tolerance will ensue.Bauman et al 3 performed a 75 g oral glucose tolerance test in 100 male veterans with SCI and in 50 able-bodied veteran controls. According to criteria established by the World Health Organization, 5 22% of those with SCI were diabetic whereas only 6% of the control group were diabetic. Eighty-two per cent of the controls had normal oral glucose tolerance, compared with 38% of those with quadriplegia and 50% of those with paraplegia. Subjects with SCI had signi®cantly higher mean plasma glucose and insulin values at several points during the oral glucose tolerance test when compared with controls ( Figure 1). In subgroups, determinants of insulin sensitivity were measured: per cent lean body mass, per cent fat mass, and cardiopulmonary ®tness. Values for insulin sensitivity were linearly related with those of ®tness (VO 2 max) determined from a progressive incremental upper-body exercise stress test. Insulin sensitivity was suggestively correlated with lean body mass, and negatively correlated with body fat. Thus, in a relatively small subgroup of untrained subjects with paraplegia, the strongest determinant of insulin sensitivity was cardiopulmonary ®tness.In 201 non-veteran subjects with SCI, Bauman et al 2 studied the relationship of oral carbohydrate tolerance after a 75 g glucose load to several variables, including level and completeness of lesion, gender, ethnicity, age, duration of injury, and anthropometric measures. Of the total group, 27 (13%) had diabetes mellitus and 56 (29%) had impaired glucose tolerance. 2,6 The subjects with complete tetraplegia had sign®cantly worse carbohydrate tolerance (Figure 2) and were more frequently classi®ed with a disorder of carbohydrate tolerance than the other neurological de®cit subgroups. 2 There were no signi®cant gend...

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“…4,6,23 These newly formed fibers, thoroughly characterized at the ultrastructural level, contain a poorly developed contractile system with many degenerated elements. 4 These incompletely differentiated fibers appear to arise from satellite cells that have detached from their parent myofibers, representing an "abortive" attempt at myogenesis.…”

mentioning

confidence: 99%

“…4 Schmalbruch and colleagues described similar myofibers in rat muscle denervated for 6 -10 months. 23 As small as 1 m in diameter, the majority of these muscle cells were so small that they could not be identified by routine light microscopy. Schmalbruch and colleagues further noted that some of the smaller fibers were completely devoid of myofilaments.…”

mentioning

confidence: 99%

Myogenesis in human denervated muscle biopsies

2007

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Electron microscopic studies of long-term denervated rat muscles have identified very small, immature myofibers that are believed to arise from detached satellite cells that have fused to form new fibers within the interstitial space. At present, it is unknown whether and to what extent equivalent fibers exist in denervated human muscle. Serial sections of muscle biopsies from 66 patients diagnosed with polyneuropathy or amyotrophic lateral sclerosis were immunolabeled with anti-NCAM and antineonatal myosin heavy chain monoclonal antibodies that are both neurally and developmentally regulated. We evaluated 200 myofibers in each section. Of the biopsy specimens, 75% contained small myofibers that showed a thin perinuclear cytoplasmic rim. Small fibers expressing neonatal myosin heavy chain (MHCnϩ) were found in all of these biopsies (100%) and NCAMϩ fibers in 98%. The percentage of MHCnϩ small fibers averaged 82% and NCAMϩ small myofibers averaged 40%. The percentage of NCAMϩ small fibers was significantly lower than that of MHCnϩ fibers. In contrast, the percentage of MHCnϩ vs. NCAMϩ angular atrophic fibers did not show a significant difference. A substantial subset of neurogenic biopsies showed small fibers that differ from angular atrophic fibers both in size and expression pattern of MHCn and NCAM. Myogenesis appears to be a frequent finding in neurogenic atrophy.

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Morphology of long‐term denervated rat soleus muscle and the effect of chronic electrical stimulation.

Cited by 127 publications

References 17 publications

Effects of chronic electrical stimulation on contractile properties of long‐term denervated rat skeletal muscle.

Effects of chronic electrical stimulation on contractile properties of long‐term denervated rat skeletal muscle.

Risk factors for atherogenesis and cardiovascular autonomic function in persons with spinal cord injury

Myogenesis in human denervated muscle biopsies

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