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1.
Several studies have reported that growth and differentiation of cultured myoblasts can be facilitated by applying appropriate mechanical stimulus. However, the effects of mechanical stimulus on the characteristics of muscle fibers have not yet been fully elucidated. In this study, we gave mechanical stress to C2C12 cells, which were myoblasts derived from mice skeletal muscle. The following myosin heavy chain (MHC) isoforms were investigated in order to clarify muscle characteristics: MHC-2b, 2d and 2a, all of which are fast-twitch fibers. After inoculating cells on a silicone chamber, the chamber was mechanically stretched, and a LightCycler was used to measure the mRNA expression of each MHC isoform at several times. The results showed that, with mechanical stretching, the expression of MHC-2b was initially high. On the other hand, without stretching, the expression of MHC-2d increased over time, but with stretching, it was hardly seen. Furthermore, the expression of MHC-2a was significantly high in the stretching group. These results of this study suggest that, when intermittently stimulated, myoblasts express increased levels of MHC-2a isoform. Therefore, it is indicated that myocytes respond to environmental changes not only to facilitate growth and differentiation, but also to alter muscle function actively at the MHC isoform level. 相似文献
2.
骨骼肌纤维类型及其表达的专一蛋白同功型的多样性,是骨骼肌功能和适应性的结构和分子基础.肌球蛋白重链同功型被认为是决定肌纤维快、慢类型的主要因素,已成为区分肌纤维类型和研究肌适应性的分子标志.运动可以导致肌球蛋白重链不同亚型之间的转变.本文就肌球蛋白重链与骨骼肌纤维类型的关系,以及不同运动模式对骨骼肌纤维肌球蛋白重链同功型转变的影响作一综述. 相似文献
3.
Akihiko Ishihara Kazuo Itoh Yasuharu Oishi Minoru Itoh Chiyoko Hirofuji Hitomi Hayashi 《Pflügers Archiv : European journal of physiology》1995,429(5):601-606
Histochemical fibre-type composition and myosin heavy chain isoform component in the soleus muscle were studied in normoxic rats at postnatal ages of 5, 10, 15, and 20 weeks and in rats exposed to hypobaric hypoxia (460 torr) for 5 weeks from postnatal ages of 5, 10, and 15 weeks. The increase in the percentage of type I fibres and the concomitant decrease in that of type IIa fibres in the soleus muscle of normoxic rats were observed until 15 weeks of age. On the other hand, no change in the fibre-type composition of the muscle during postnatal development was observed in hypoxic rats, irrespective of the age at which they were exposed to hypoxia. The changes in the myosin heavy chain isoform component (MHC I and MHC IIa) of the muscle during postnatal development and by hypoxia corresponded well with those in the muscle fibre-type composition. It is concluded that hypobaric hypoxia inhibits the growth-related shift of muscle fibre-types from type IIa to type I and of myosin heavy chain isoforms from MHC IIa to MHC I in the rat soleus muscle, and that there are no changes in the muscle fibre-type composition or the myosin heavy chain isoform component caused by hypoxia after the shifts in these parameters which occur during postnatal development are completed. 相似文献
4.
Pansarasa O D'Antona G Gualea MR Marzani B Pellegrino MA Marzatico F 《European journal of applied physiology》2002,87(6):550-555
We evaluated the effects of testosterone overload on mitochondrial superoxide dismutase (MnSOD), cytochrome oxidase (COX)
and citrate synthase (CS) activities of the rat superficial gastrocnemius both in non-exercised muscle and following moderate
endurance training. Basal (bLPO) and stimulated (sLPO) lipid peroxidation was measured as an index of oxidative tissue damage.
Furthermore, to assess the relationship between exercise and testosterone-induced metabolic adaptations and contractile protein
expression, the distribution of myosin heavy chain (MHC) isoforms was analysed by SDS-PAGE. Samples were obtained from: controls
(C), rats treated with testosterone propionate (Tp) (TP, 5 mg kg–1 i.m. 6 days/week), trained rats (E, 5 days/week) and rats trained and treated with Tp (ETP). MnSOD significantly increased
in E and TP in comparison with C and ETP. Training induced a significant increase in COX activity both in E and ETP whereas
a statistical reduction was observed in TP in comparison with the other groups. Moreover, testosterone administration was
associated with a significant reduction in CS activity which significantly increased in ETP. A reduction in lipid peroxidation
was observed in E and ETP in comparison with controls both in basal and stimulated conditions, whereas TP showed a significant
increase of bLPO. In trained rats enzymatic changes were correlated with an increase in the proportion of fast oxidative MHC-2A
and MHC-2X with decrease of the proportion of fast MHC-2B. In contrast, Tp treatment induced an increase in the proportion
of MHC-2B whereas MHC-2A and MHC-2X disappeared. Finally, ETP showed a reduction in MHC-2B and an increase in MHC-1 and MHC-2X.
These data suggest that testosterone supplementation seems not to significantly modify the metabolic adaptation induced by
exercise in gastrocnemius muscle. Furthermore, testosterone overload to non-exercised rats seems to reduce the mitochondrial
function and increase the lipid peroxidation of the muscle.
Electronic Publication 相似文献
5.
We have examined the effect of male sex hormones on the myosin heavy chain (MHC) expression of the soleus and extensor digitorum
longus (EDL) muscles. Young male adult Wistar rats were treated over a 25-day period with either oil (CON, n = 8), nandrolone (nortestosterone decanoate, NAN, n = 8), nandrolone combined with endurance exercise (treadmill running, NAN+EXE, n = 8), or were castrated (CAS, n = 8). The MHC composition of the soleus and EDL muscles was measured by electrophoresis. Castration and treatment with nandrolone
had no effect (P > 0.05) on the relative levels of MHC in the soleus and EDL. In contrast, in NAN+EXE rats, the relative level of MHC-1 increased
[slow isoform; mean (SD) 97.6 (4.7)% in NAN+EXE rats, versus 86.5 (7.5)% in CON rats] and MHC-2a decreased [fast isoform;
2.4 (4.7)% in NAN+EXE, versus 13.5 (7.5)% in CON rats], only in the soleus (P < 0.05). In conclusion, it appears that endogenous anabolic/androgenic steroids are not essential for the maintenance of
the MHC expression of fast- and slow-twitch muscles in the young adult male rat. In addition, nandrolone combined with endurance
exercise induced a shift from a fast to a slower MHC phenotype of the slow-twitch muscle.
Accepted: 27 July 1999 相似文献
6.
D'Antona G Megighian A Bortolotto S Pellegrino MA Marchese-Ragona R Staffieri A Bottinelli R Reggiani C 《Journal of muscle research and cell motility》2002,23(3):187-195
In the present study we aimed to determine the functional properties and the myosin heavy chain (MHC) isoform composition of single chemically skinned fibres from the vocal muscle of four adult men (age: 55–67 years). Single fibres, dissected from the bioptic samples, were chemically skinned and isometric tension (P
0) and maximal shortening velocity (V
0) were measured at pCa 4.6. MHC and myosin light chain (MLC) composition of fibre segments and MHC distribution of the biopsy samples were analysed by SDS–poly-acrylamide gel electrophoresis (SDS—PAGE) and densitometry. Four MHC isoforms (1, 2A, 2X and a fourth isoform, provisionally called L) and five MLC isoforms (MLC1s, MLC1f, MLC3f, MLC2f, MLC2s) were identified. The major findings of this study were: (1) fast MHC isoforms (in particular MHC-2A) and fast fibres were predominant, (2) one-third of the fibres were mixed or hybrid, i.e. expressed more than one MHC isoform, (3) V
0 and P
0 values were determined by the MHC isoform composition and mixed fibres showed functional properties which were intermediate between pure fibres; MHC-L was associated with V
0 values similar to those of MHC-2A, (4) compared with limb muscles, V
0 values of laryngeal fibres were similar to those of limb muscle fibres containing the same MHC isoform whereas P
0 values were lower for slow and fast 2X fibres and similar for fibres expressing MHC-2A. 相似文献
7.
Martrette JM Hartmann N Westphal A Favot L 《Journal of muscle research and cell motility》2004,25(4-5):297-302
The influence of agonist (dexamethasone) and antagonist (mifepristone) of glucocorticoïd receptor during controllable painless stress was evaluated on myosin heavy chains expression in three masticatory and two nape rat muscles: anterior digastric (AD), anterior temporalis (AT), masseter superficialis (MS), longissimus capitis (L) and rectus capitis dorsalis major (R). The relative amounts of myosin heavy chain (MHC) protein isoform contained were significantly affected in four muscles studied by dexamethasone and in three muscles studied under mifepristone, versus control during the stress procedure, after only 1 week of treatment. The control group AT muscles contained respectively 18.2% of MHC 2A, 34.5% of MHC 2X and 47.4% of MHC 2B. The effects of dexamethasone and mifepristone were opposite in this muscle: under dexamethasone, the relative proportions of the three isoforms were 14.2, 31.0 and 54.8%: consequently, MHC 2A and 2X decreased with the profit of 2B. Under mifepristone, the relative proportions were 21.1, 36.6 and 42.3% (MHC 2A and 2X increased to the detriment of 2B). The L muscle was not affected by the two treatments and MS muscle was only affected by dexamethasone. Dexamethasone increased MHC 2B to the detriment of MHC 2A in MS, AD and R. Mifepristone and dexamethasone induced the same changes in AD. The mifepristone treatment decreased the MHC 2X profile in R. Under dexamethasone, four muscles exhibited a significantly higher proportion of the more rapid isoforms than under mifepristone. A previous work showed that controllable stress induced a marked increase in the relative expression of MHC 2B in the same skeletal muscles (Martrette et al., 1998). Our results confirm then a significant participation of glucocorticoïd in MHC isoform expression during controllable stress. 相似文献
8.
Despite many studies looking at the distribution of myosin heavy chain (MHC) isoforms across a transverse section of muscle, knowledge of MHC distribution along the longitudinal axis of a single skeletal muscle fiber has been relatively overlooked. Immunocytochemistry was performed on serial sections of rat extensor digitorum longus (EDL) muscle to identify MHC types I, IIA, IIX, IIY, and IIB. Sixteen fascicles which contained a total of 362 fibers were randomly and systematically sampled from the three EDL muscles. All MHC type I and type II isoforms were expressed. Segmental expression occurred within a very limited segment. MHC isoform expression followed the accepted traditional order from I?IIA?IIX?IIB, however, in some samples expression of an isoform was circumvented from IIB to I or from I to IIB directly. Segmental distribution of MHC isoforms along a single muscle fiber may be because of the myonuclear domain. Anat Rec, 300:1636–1642, 2017. © 2017 Wiley Periodicals, Inc. 相似文献
9.
Lowe DA Husom AD Ferrington DA Thompson LV 《Mechanisms of ageing and development》2004,125(9):619-627
We tested the hypothesis that Ca(2+)-activated myosin ATPase activity is lower in muscles of aged rats relative to muscles of young rats, independent of changes in myosin isoform expression. Myofibrils were prepared from permeabilized fibers of soleus, plantaris, and semimembranosus muscles of young (8-12 months) and aged (32-38 months) F344 x BN rats and assayed for resting myosin ATPase, Ca(2+)-activated myosin ATPase, and myosin heavy chain (MHC) and myosin light chain (MLC) isoform compositions. Resting myosin ATPases were not affected by age in any muscle (P > or = 0.42). Ca(2+)-activated myosin ATPases of soleus and plantaris myofibrils were not affected by age (P > or = 0.31) but were 16% lower in semimembranosus myofibrils from aged rats (0.448 +/- 0.019 micromol P(i)/min/mg) compared to young rats (0.533 +/- 0.031 micromol P(i)/min/mg; P = 0.03). Correspondingly, maximal unloaded shortening velocity of single semimembranosus fibers from aged rats was slow (4.6 +/- 0.2 fiber lengths/s) compared with fibers from young rats (5.8 +/- 0.3 fiber lengths/s; P < 0.01). No age-related changes in MHC or regulatory MLC isoforms were detected in any muscle (P > or = 0.08) but changes in the essential MLC occurred in plantaris and semimembranosus muscles. The data indicate that Ca(2+)-activated myosin ATPase activity is reduced with age in semimembranosus muscle, independent of age-related changes in MHC isoform expression, and is one mechanism contributing to age-related slowing of contraction in that muscle. 相似文献
10.
11.
Jaak Jürimäe Peter J. Abernethy Kirsten Blake Michael T. McEniery 《European journal of applied physiology》1996,74(3):287-292
The purpose of this investigation was to determine whether 12 weeks of resistance training, which increased arm girth (5%) and forearm extensor strength (39%), also altered the myosin heavy chain (MHC) characteristics of the triceps brachii muscle. Fifteen healthy, active men volunteered to participate under experimental (n = 11) or control (n = 4) conditions. The experimental group completed four sets of eight to 12 repetitions for each exercise (i.e. triceps pushdown, close grip bench press, triceps kickbacks and biceps curl) with loads of between 70–75% of one repetition maximum (1RM) three times a week. The inter-set and inter-exercise recovery period was only 90 s. Skeletal muscle tissue was removed from the triceps brachii muscle prior to (W0) and following 4 (W4), 8 (W8) and 12 (W12) weeks of the investigation. Samples were analysed for MHC isoform content using 6% sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). MHC isoform composition in the control group did not change significantly. However, the percentage of MHC type IIb isoform decreased significantly from W0 to W4 and again from W4 to W12 [W0: 39.7 (9.2); W12: 29.2 (8.2)%] in the experimental condition. The increments in MHC type IIa [W0: 34.0 (9.9); W12: 41.5 (10.4)] and type I [W0: 26.3 (7.9); W12: 29.3 (9.6)] isoforms were not significant for the experimental group. However, the effect size (ES) transformation of changes in types IIa MHC content was moderate (ES = 0.75). Changes in MHC isoform content were not significantly correlated with changes in 1RM strength for the triceps pushdown exercise. These data indicated that resistance training rapidly, and in an ongoing manner, changed the contractile protein profile of trained skeletal muscle. However, changes in MHC isoform composition in the first 12 weeks of training were not implicated in the development of 1RM triceps pushdown strength. 相似文献
12.
Pellegrino MA Brocca L Dioguardi FS Bottinelli R D'Antona G 《European journal of applied physiology》2005,93(5-6):655-664
The aims of the present study were as follows: (1) to examine the adaptational changes to chronic endurance voluntary exercise and (2) to investigate the effects of amino acid supplementation on the adaptational changes induced by endurance training in hindlimb (gastrocnemius, tibialis, soleus) and respiratory (diaphragm) muscles of mice. Male C57Bl6 mice were divided in four groups: control sedentary, sedentary supplemented with amino acid mixture (BigOne, 1.5 mg g day–1 in drinking water for 8 weeks), running (free access to running wheels for 8 weeks), and running supplemented with amino acid mixture. Myosin heavy chain (MHC) isoform distribution was determined in all muscles considered. Fiber cross-sectional area (CSA) was measured in the soleus muscle. In all muscles except the tibialis, endurance training was associated with an overall shift towards the expression of slower MHC isoforms. Amino acid supplementation produced a shift towards the expression of faster MHC isoforms in the soleus and diaphragm muscles, and partially antagonized the effects of training. Immunohistochemical analysis of CSA of individual muscle fibers from the soleus muscle suggests that voluntary running produced a decrease in the size of type 1 fibers, and amino acid supplementation during training resulted in an increase in size in both type 1 and type 2A fibers. Collectively, these results suggest that the endurance adaptations induced by voluntary running depend on the muscle type, and that amino acid supplementation is able to modulate both fiber size and MHC isoform composition of skeletal muscles in sedentary and exercised mice. 相似文献
13.
Rivero José-luis L. Serrano Antonio L. Barrey Eric Valette Jean P. Jouglin Maggy 《Journal of muscle research and cell motility》1999,20(2):211-221
Combined methodologies of enzyme-linked immunosorbent assay (ELISA), sodium dodecyl sulphate polyacrilamide gel electrophoresis (SDS-PAGE), immunoblotting, traditional myofibrillar ATPase (mATPase) histochemistry and immunocytochemistry of whole biopsied samples were used to study myosin heavy chain (MHC) isoforms in the equine gluteus medius muscle. The ELISA technique allowed the quantification of the three MHC isoforms known to be present in different horse muscles: slow (MHC-I) and two fast (termed MHC-IIA and MCH-IIX). The SDS-PAGE method resolved MHCs in three bands: MHC-I, MHC-IIX and MHC-IIA from the fastest to the slowest migrating band and a quantification by densitometry for each MHC isoform was also possible. The identity of these three MHCs was confirmed by immunoblots with specific monoclonal antibodies. Five fibre types were defined immunohistochemically according to their MHC content: I, I + IIA, IIA, the hybrid IIAX and IIX. When quantitative data obtained with the four different methodologies were combined and compared, they were consistent and, when considered together, showed significant correlation. Nevertheless, the percentage of MHC-IIA histochemically derived was underestimated, while that of MHC-IIX was overestimated in comparison with the immunocytochemical determination of these MHC isoforms. The percentage of MHC-I obtained by ELISA technique was underestimated. In short, these integrated methods for the analysis of MHCs at the protein level demonstrate that equine skeletal muscle does not express the MHC-IIB, so type II fibres have been misclassified in numerous previous studies based upon the very traditional mATPase histochemistry. They also offer new prospects for muscle fibre typing in equine experimental studies and veterinary medicine. 相似文献
14.
S. Masuda T. Hayashi T. Hashimoto S. Taguchi 《Acta physiologica (Oxford, England)》2009,195(4):483-494
Aim: The dystrophin–glycoprotein complex (DGC) and focal adhesion complex (FAC) are transmembrane structures in muscle fibres that link the intracellular cytoskeleton to the extracellular matrix. DGC and FAC proteins are abundant in slow‐type muscles, indicating the structural reinforcement which play a pivotal role in continuous force output to maintain posture for long periods. The aim of the present study was to examine the expression of these structures across fast‐type muscles containing different myosin heavy chain (MHC) isoform patterns which reflect the fatigue‐resistant characteristics of skeletal muscle. Methods: We measured the expression of dystrophin and β1 integrin (representative proteins of DGC and FAC respectively) in plantaris, extensor digitorum longus, tibialis anterior, red and white portions of gastrocnemius, superficial portion of vastus lateralis and diaphragm, in comparison with soleus (SOL) and cardiac muscle from rats. Results: The expression of dystrophin and β1 integrin correlated positively with the percentage of type I, IIa and IIx MHC isoforms and negatively with that of type IIb MHC isoform in fast‐type skeletal muscles, and their expression was abundant in SOL and cardiac muscle. Conclusion: Our results support the idea that DGC and FAC are among the factors that explain the fatigue‐resistant property not only of slow‐type but also of fast‐type skeletal muscles. 相似文献
15.
T. SUGIURA H. MATOBA H. MIYATA Y. KAWAI N. MURAKAMI 《Acta physiologica (Oxford, England)》1992,144(4):419-423
Sugiura , T., Matoba , H., Miyata , H., Kawai , Y. & Murakami , N. 1992. Myosin heavy chain isoform transition in ageing fast and slow muscles of the rat. Acta Physiol Scand 144 , 419423. Received 26 August 1 991 , accepted 3 December 1991. ISSN 0001–6772. Laboratory of Biomechanics and Physiology, Faculty of Liberal Arts, Yamaguchi University, Yamaguchi, Faculty of Integrated Arts and Sciences, Tokushima University, Tokushima, and Department of Physiology, Yamaguchi University School of Medicine, Ube, Yamaguchi, Japan. Using gradient sodium dodecyl sulphate-polyacrylamide gel electrophoresis, myosin heavy chain (MHC) isoforms were studied in the extensor digitorum longus (EDI,) and the soleus muscles of male Wistar rats at different ages ( 5, 10 , 20 weeks, 1 and 2 years). In the EDL muscle, four types of MHC isoforms were observed in all age groups. There was an increase in the percentage of HCIId and a concomitant decrease in the percentage of HCIIb with increasing age. No significant difference was observed in the percentages of HCI and HCIIa isoforms in all the age groups. In contrast, the soleus muscle contained two MHC isoforms, HCI and HCIIa. There was an increase in the percentage of HCI and a concomitant decrease in the percentage of HCIIa with increasing age. These results suggest that age-related changes in the MHC isoforms in both the fast-twitch EDI, and the slow-twitch soleus muscles are one factor underlying the age-related decrease in the speed of muscle contraction. 相似文献
16.
Robert J. Talmadge Roland R. Roy V. Reggie Edgerton 《Anatomical record (Hoboken, N.J. : 2007)》1999,255(2):188-201
The effects of a chronic (up to 360 days) reduction in neuromuscular activity (defined as electrical activation and loading) on myosin heavy chain (MHC) isoform expression in the rat soleus muscle were studied. A complete mid‐thoracic (T7‐T8) spinal cord transection (ST) was used to induce a reduction in soleus muscle neuromuscular activity. Electrophoretic analyses revealed that MHC‐I was progressively decreased after ST, accounting for approx. 90% of the total soleus MHC in controls and only approx. 12% 1 year after ST. The reductions in the proportion of MHC‐I were countered by increases in MHC‐IIa and MHC‐IIx with the increase in MHC‐IIx preceding the increase in MHC‐IIa. Curiously, MHC‐IIb was expressed only at very low levels. Thus, a complete transformation from predominantly MHC‐I to MHC‐IIb did not occur. Many fibers (up to approx. 80%) contained multiple MHCs (hybrid fibers) after ST. The proportion of hybrid fibers was maintained at a high level (approx. 50%) 1 year after ST. These data suggest that: 1) a prolonged reduction in neuromuscular activity was not sufficient to induce high level MHC‐IIb expression by the soleus muscle; and 2) hybrid fibers were not simply transitional fibers. Thus, it appears that under appropriate conditions hybrid fibers may represent a “stable” fiber phenotype. Anat Rec 255:188–201, 1999. © 1999 Wiley‐Liss, Inc. 相似文献
17.
Parente V D'Antona G Adami R Miotti D Capodaglio P De Vito G Bottinelli R 《European journal of applied physiology》2008,104(5):885-893
Four elderly women (78 ± 4.3 years) were resistance trained (RT) for one year and needle biopsies of the vastus lateralis
muscle were taken pre- and post-RT. A training intensity of 60% one-repetition maximum (1RM) was adopted for the entire duration
of the study. Following RT, significant gain in isometric force of the quadriceps muscles was observed and MHC isoform distribution
of vastus lateralis muscle showed a very significant shift from MHC-1 and MHC-2X towards MHC-2A, i.e. a bi-directional shift.
A large population (n = 310) of individual skinned muscle fibres were dissected from biopsy samples and used for determination of cross-sectional
area (CSA), specific force (Po/CSA) and unloaded shortening velocity (Vo) at 12°C and maximum activation. Fibres were classified
on the basis of their MHC isoform content determined by SDS-PAGE in three pure fibre types (1, 2A and 2X) and two hybrid fibre
types (1-2A and 2AX). Whereas the CSA of individual muscle fibres did not change, Po/CSA was significantly higher in both
type 1 and type 2A fibres post training. Vo of type 1 fibres was significantly higher post-training, whereas no change in
Vo was observed in type 2A fibres. The number of pure type 2X fibres was very low especially post-training and did not enable
a statistically significant comparison. The data suggest that in elderly women moderate and prolonged RT: (1) can determine
similar adaptations in MHC distribution of skeletal muscle to those expected in young subjects; (2) can improve function of
muscle fibres. 相似文献
18.
J. L. ANDERSEN H. KLITGAARD J. BANGSBO B. SALTIN 《Acta physiologica (Oxford, England)》1994,150(1):21-26
The myosin heavy chain (MHC) composition of single fibres (n= 2171) was analysed with an electrophoretic technique in biopsy material from m. vastus lateralis of two groups of soccer players before and after a 3-month period of either strength- (n= 8) or non-training (control) (n= 6). Traditional myofibrillar ATPase histochemistry demonstrated a decrease in type IIA fibres with strength-training (35.4 ± 2.1 vs. 26.7 ± 2.4% (P < 0.05)). This was not observed in the non-training group (25.7 ± 4.6 vs. 23.8 ± 1.7%). One-dimensional electrophoresis on muscle homogenates showed no significant change in the amount of MHC isoforms in either of the two groups. The MHC isoform I IB was undetectable in all but three samples. No changes in the proportions of fibres containing any of the MHC isoforms were observed. Fibres containing only MHC isoform I IB were found in very small numbers (only 11 out of 2171). Before the experimental period, between 6 and 10% histochemical type IIB fibres were found in both groups. This was identical with the proportion of fibres showing co-existence of MHC isoforms IIA and IIB, but in contrast to the very few fibres containing only MHC isoform IIB. This suggests that nearly all histochemical type IIB fibres of the soccer players display co-existence of both MHC isoform IIA and IIB. No major change in the muscle fibre area of the two groups was observed. The strength-training group increased mean power output in a short-term dynamic knee-extensor test after strength-training (119 ± 6.6 vs. 136.5 ± 4.7 W (P < 0.01)), whereas no change was observed in the non-training group (151.2 ± 4.5 vs. 148.4 ± 6.5 W). 相似文献
19.
20.
Objective and design: The objective of this study was to characterize the response of skeletal muscle to a localized inflammation induced by the
inflammatory agent casein.
Methods: An inflammatory agent, casein, was injected into the right hindlimb and saline was injected into the left hindlimb of normal
adult mice, once daily for six consecutive days. Inflammatory response was monitored by immunohistochemical labeling of leukocytes.
Muscle protein levels were determined by electrophoresis and muscle function was determined by isometric force measurements.
Results: Local inflammation was induced by casein in association with the accumulation of extensive neutrophils and macrophages in
the solues muscle. This local inflammation resulted in a shift in myosin heavy chain (MHC) isoform expression and a significant
reduction in total MHC concentration in the soleus. Maximal twitch and tetanic forces were significantly reduced in the inflamed
soleus. Contractile function in soleus was fully restored after two weeks of recovery, along with the restoration of protein
concentration and the disappearance of inflammatory cells.
Conclusion: This study establishes a unique and robust model in which mechanisms of local inflammation induced muscle protein degradation,
reduction of contractile force, and subsequent recovery from this condition can be further studied.
Received 22 February 2008; returned for revision 17 April 2008; received from final revision 2 July 2008; accepted by M. Parnham
7 July 2008 相似文献