Denervation and reinnervation of fast and slow muscles. A histochemical study in rats.

Jaweed, M.M.; Herbison, Gerald J.; Ditunno, John F.

doi:10.1177/23.11.127809

Cited by 85 publications

(35 citation statements)

References 19 publications

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“…These effects appear to be even more marked than those observed in denervated type 1 fibers from soleus muscle (33), and they contradict the hypothesis that type 2B fibers are insensitive to the action of the nerve. Because these changes of type 2B fiber properties occurred before any modifications in the MHC isoform expression, our results corroborate the opinion that early changes of muscle contractile properties are primarily due to alterations of the muscle activation process (24,27,31,33,43,44,53). Consistently, changes of the excitationcontraction coupling process were noted in the denervated rat EDL muscle (16).…”

Section: Discussionsupporting

confidence: 88%

Early changes of type 2B fibers after denervation of rat EDL skeletal muscle

Germinario¹,

Esposito²,

Megighian³

et al. 2002

Journal of Applied Physiology

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Early changes of type 2B fibers after denervation of rat EDL skeletal muscle. J Appl Physiol 92: 2045-2052, 2002. First published December 21, 2001 10.1152/japplphysiol.00673.2001.-Skeletal muscle type 2B fibers normally receive a moderate level of motoneuron discharge. As a consequence, we hypothesize that type 2B fiber properties should be less sensitive to the absence of the nerve. Therefore, we have investigated the response of sarcoplasmic reticulum and myofibrillar proteins of type 2B fibers isolated from rat extensor digitorum longus muscle after denervation (2 and 7 days). Single fibers were identified by SDS-PAGE of myosin heavy chain isoforms. Electrophysiological and isometric contractile properties of the whole muscle were also analyzed. The pCa-tension relationship of type 2B single fibers was shifted to the left at 2 days and to right at 7 days after denervation, with significant differences in the Hill coefficients and pCa threshold values in 2-vs. 7-day-denervated fibers. The sarcoplasmic reticulum Ca 2ϩ uptake capacity and rate significantly decreased after 2 days of denervation, whereas both increased at 7 days. Caffeine sensitivity of sarcoplasmic reticulum Ca 2ϩ release was transitory and markedly increased in 2-day-denervated fibers. Our results indicate that type 2B fiber functional properties are highly sensitive to the interruption of nerve supply. Moreover, most of 2-day-denervated changes were reverted at 7 days. calcium sensitivity; chemically skinned muscle fibers; sarcoplasmic reticulum; extensor digitorum longus SKELETAL MUSCLES ARE COMPOSED of a variety of fiber types with different morphological, biochemical, and functional characteristics (36,42). During embryonic and postnatal developments, differentiation into the different fiber types is mainly controlled by innervation, with the pattern and amount of neuromotor impulses playing a major role (21,35,42), although the weight of neurotrophic factors cannot be excluded. Therefore, it is not surprising that denervation causes profound changes to skeletal muscle properties. Some alterations, related to sarcoplasmic reticulum properties, occur very early after denervation, whereas alterations of the myofibrillar proteins profiles need, in general, more time. We have, in fact, previously described changes in sarcoplasmic reticulum properties of the slow-twitch type 1 fibers from denervated soleus muscle showing that the maximum Ca 2ϩ uptake capacity and rate were reduced after 2 days of denervation and increased at 7 days (33). Moreover, the initial Ca 2ϩ release rate was reduced in 2-day-denervated type 1 fibers. These changes in sarcoplasmic reticulum properties were related to mechanical changes of the denervated muscle.In this study, we examined whether also the sarcoplasmic reticulum properties of fast-twitch fibers are nerve dependent and, therefore, need an intact innervation. We focused our attention to type 2B fibers from the extensor digitorum longus (EDL) muscle, i.e., to fibers that, within the continuum of fiber types (1...

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Section: Discussionsupporting

confidence: 88%

Early changes of type 2B fibers after denervation of rat EDL skeletal muscle

Germinario¹,

Esposito²,

Megighian³

et al. 2002

Journal of Applied Physiology

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“…The fiber cross-sectional areas were regenerated 2 to 3 weeks after freezing. It was roughly estimated that it took approximately 3 weeks for the sciatic nerve to contact the soleus muscles over approximately 20 mm, which was compatible with data previously reported [10][11][12] . The cross-sectional area of type I and II fibers showed a progressive decrease with time after denervation 4,12) .…”

Section: Discussionsupporting

confidence: 79%

“…It was roughly estimated that it took approximately 3 weeks for the sciatic nerve to contact the soleus muscles over approximately 20 mm, which was compatible with data previously reported [10][11][12] . The cross-sectional area of type I and II fibers showed a progressive decrease with time after denervation 4,12) . The denervation produced serious atrophy compared to immobilization due to muscle disuse caused by paralysis and tenotomy in the deprivation of trophic substances 1,13,14) .…”

Section: Discussionsupporting

confidence: 79%

The Effect of Denervation and Subsequent Reinnervation on the Morphology of Rat Soleus Muscles.

et al. 2002

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Abstract.To investigate the effect of denervation and subsequent reinnervation on skeletal muscle, a histochemical study was performed on the soleus muscles of rats. Partial denervation was carried out by freezing the sciatic nerve locally, and the change in the nerve and the soleus muscles was examined for 5 weeks. The muscle fiber cross-sectional area of the denervated soleus muscles progressively declined to a minimum 2 weeks after the injury (type I fibers, 1209.1 ± 248.3 µm 2 ; type II fibers, 802.4 ± 126.8 µm 2 ) and began to reverse the decline at 3 weeks. The type II fiber ratios to total fiber of the denervated sides were consistently higher than the control levels, and muscle fibers stained in both acid preincubation and alkaline preincubation were observed. The proportion of type II fibers in the soleus muscles showed an increase and consequently a decrease with a short delay in response to denervation and consequent reinnervation. These data suggest that denervation elicits an alteration in fiber type composition and a reduction in fiber size. The increase of type II fibers seemed to occur in hybrid fibers containing both myosin heavy chains I and II at varying ratios in the same fibers. The reinnervation took the crucial role of recovering from atrophy and composing the integrity of the soleus muscles. However, the ability to generate muscle tension needs a much longer time to recover. This suggests a need to investigate interventions to facilitate the functional recovery of partially-denervated muscle.

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“…Most authors report that target fibers are more frequently found in type I fibers. However, Jaweed et al (1975), studying rats submitted to denervation, observed the presence of this phenomenon only in type II fibers.…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Study of the Denervated Diaphragm in Rats

et al. 2013

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SUMMARY:The structural alterations that occur in the muscle fibers of denervated rat diaphragms were studied. Fifteen adult male albino rats (Rattus norvegicus) with a mean weight of 200 g and about 60 days of age were used. Chronically denervated diaphragms were obtained and the animals were sacrificed after 4, 8 and 12 weeks of denervation. The left antimere of the diaphragm was denervated by sectioning of the phrenic nerve and the right antimere served as control. Each antimere was divided into fragments, which were used for analysis transmission electron microscopy. During the initial phase of denervation (4 weeks), ultrastructural muscle modifications appeared in scattered fibers and in foci along these fibers. Muscle fibers with foci of less dense and loosely arranged myofibrils, disorganized Z line, displaced T tubules, and central nucleus exhibiting reentrances and fragmented aspect were observed. After 8 weeks, formation of large aggregates of small elongated mitochondria showing altered cristae, matrix inclusions and increased electron density was noted. At 12 weeks of denervation the alterations were found to be more drastic. Nuclei with internal deposits of myofibrillar or amorphous material were observed. In these fibers, vacuoles harbored enormous myeloid structures in the subsarcolemmal or intermyofibrillar region.

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Denervation and reinnervation of fast and slow muscles. A histochemical study in rats.

Cited by 85 publications

References 19 publications

Early changes of type 2B fibers after denervation of rat EDL skeletal muscle

Early changes of type 2B fibers after denervation of rat EDL skeletal muscle

The Effect of Denervation and Subsequent Reinnervation on the Morphology of Rat Soleus Muscles.

Ultrastructural Study of the Denervated Diaphragm in Rats

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