| 1. |
- Edman, Anne-Christine, et al.
(författare)
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Structural diversity in muscle fibres of chicken breast
- 1988
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Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 251:2, s. 281-289
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Tidskriftsartikel (refereegranskat)abstract
- hicken breast muscle is usually considered to be a relatively homogeneous white muscle and has therefore been widely used for studies of muscle proteins. In a previous study, however, we have found different M-region structures in different fibres from this muscle. Because of this result, we have now carried out a combined histochemical and ultrastructural survey of this muscle. In particular, we have made use of large transverse cryo-sections that include most of the muscle cross-section. Although the white region is fairly homogeneous in fibre content according to normal histochemical criteria (mATPase), we have found that there is a gradation of fibre structure across the muscle. The bulk of the muscle stains conventionally for Type-II fibres according to mATPase tests (the "white" part) but, in the small "red" part of the muscle, there are also Type-I fibres together with the Type-II fibres. Superimposed on this division into Type-I and Type-II fibres are variations in fibre size, oxidative and glycolytic staining properties, and variations of Z-band width and M-band structure; there is no strict correlation among any of these parameters. The apparently uniform staining across most of the muscle when tested for myofibrillar ATPase may be a misleading indicator of fibre properties.
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| 2. |
- Lexell, Jan, et al.
(författare)
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Quantitative morphology of stimulation-induced damage in rabbit fast-twitch skeletal muscles
- 1992
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Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 269:2, s. 195-204
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to examine the contention that stimulation-induced damage, resulting in degeneration with subsequent regeneration, plays a major role in the transformation of fibre type brought about by chronic electrical stimulation. Data from histological and histochemical sections of 9-day-stimulated rabbit fast-twitch muscles were analysed with multivariate statistical techniques. Fibre degeneration and regeneration varied non-systematically between sample areas at any given cross-sectional level. In the extensor digitorum longus muscle, but not in the tibialis anterior, there was more degeneration in proximal than in distal portions of the muscle. The extensor digitorum longus muscle consistently showed more degeneration than the tibialis anterior muscle. Degeneration was less extensive for an intermittent pattern of stimulation that delivered half the aggregate number of impulses of continuous stimulation. Degeneration and regeneration varied markedly between individual rabbits in each of the groups. Sections that revealed the most degeneration and regeneration also had more fibres that reacted positively with an anti-neonatal antibody. Rigorous analysis of different sources of variation has helped to explain apparent conflicts in the literature. The incidence of muscle fibre damage in the stimulated tibialis anterior muscle is low, showing that the contribution of degenerative-regenerative phenomena to fibre type conversion in this muscle is insignificant.
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| 3. |
- Lexell, Jan, et al.
(författare)
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Stimulation-induced damage in rabbit fast-twitch skeletal muscles : a quantitative morphological study of the influence of pattern and frequency
- 1993
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Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 273:2, s. 357-362
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine whether muscle fibre degeneration brought about by chronic low-frequency electrical stimulation was related to the pattern and frequency of stimulation. Rabbit fast-twitch muscles, tibialis anterior and extensor digitorum longus, were stimulated for 9 days with pulse trains ranging in frequency from 1.25 Hz to 10 Hz. Histological data from these muscles were analysed with multivariate statistical techniques. At the lower stimulation frequencies there was a significantly lower incidence of degenerating muscle fibres. Fibres that reacted positively with an antineonatal antibody were most numerous in the sections that revealed the most degeneration. The dependence on frequency was generally similar for the two muscles, but the extensor digitorum longus muscles showed more degeneration than the tibialis anterior at every frequency. Muscles subjected to 10 Hz intermittent stimulation showed significantly less degeneration than muscles stimulated with 5 Hz continuously, although the aggregate number of impulses delivered was the same. The incidence of degeneration in the extensor digitorum longus muscles stimulated at 1.25 Hz was indistinguishable from that in control, unstimulated muscles; for the tibialis anterior muscles, this was also true for stimulation at 2.5 Hz. We conclude that damage is not an inevitable consequence of electrical stimulation. The influence of pattern and frequency on damage should be taken into account when devising neuromuscular stimulation regimes for clinical use
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