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1.
J Agric Food Chem ; 68(5): 1306-1314, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31957433

RESUMO

Dimer procyanidin B2 [epicatechin-(4ß-8)-epicatechin] (PB2) has attracted a lot of interest in nutrition and medicine because of its significant health-promoting abilities. However, the function of PB2 on different types of skeletal myofiber is still unclear. Here, we have found that PB2 significantly increased protein expression of the slow myosin heavy chain (MyHC) and decreased fast MyHC protein in C2C12 myotubes, accompanied by upregulation of mRNA expression of MyHC I, MyHC IIa, and Tnni1 and downregulation of MyHC IIx and MyHC IIb. We have also found that PB2 enhanced the activities of malate dehydrogenase and succinic dehydrogenase and reduced lactate dehydrogenase activity. PB2 promoted phosphorylation of AMPK and significantly increased mRNA expression of AMPKα1. The upstream factors of AMPK, such as phospho-LKB1, NRF1, and CaMKKß, and the downstream factors of AMPK, including Sirt1 and PGC-1α, were also increased by PB2. Specific suppression of AMPK signaling by AMPKα1 siRNA or by AMPK inhibitor compound C significantly attenuated the PB2-induced upregulation of phospho-AMPK, PGC-1α, and slow MyHC and downregulation of fast MyHC. Our findings suggested that PB2 promotes skeletal slow-twitch myofiber gene expression through the AMPK signaling pathway in C2C12 myotubes.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Biflavonoides/farmacologia , Catequina/farmacologia , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/efeitos dos fármacos , Proantocianidinas/farmacologia , Proteínas Quinases Ativadas por AMP/genética , Animais , Linhagem Celular , Regulação da Expressão Gênica/efeitos dos fármacos , Camundongos , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/metabolismo , Transdução de Sinais/efeitos dos fármacos
2.
J Exp Biol ; 223(Pt 2)2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31871118

RESUMO

Muscle fibres are classified as fast, intermediate and slow. In vitro myoblast cell culture model from fast muscle is a very useful tool to study muscle growth and development; however, similar models for slow muscle do not exist. Owing to the compartmentalization of fish muscle fibres, we have developed a slow myoblast cell culture for rainbow trout (Oncorhynchus mykiss). Slow and fast muscle-derived myoblasts have similar morphology, but with differential expression of slow muscle markers such as slow myhc, sox6 and pgc-1α We also characterized the mir-133 and mir-499 microRNA families in trout slow and fast myoblasts as a case study during myogenesis and in response to electrostimulation. Three mir-133 (a-1a, a-1b and a-2) and four mir-499 (aa, ab, ba and bb) paralogues were identified for rainbow trout and named base on their phylogenetic relationship to zebrafish and Atlantic salmon orthologues. Omy-mir-499ab and omy-mir-499bb had 0.6 and 0.5-fold higher expression in slow myoblasts compared with fast myoblasts, whereas mir-133 duplicates had similar levels in both phenotypes and little variation during development. Slow myoblasts also showed increased expression for omy-mir-499b paralogues in response to chronic electrostimulation (7-fold increase for omy-mir-499ba and 2.5-fold increase for omy-mir-499bb). The higher expression of mir-499 paralogues in slow myoblasts suggests a role in phenotype determination, while the lack of significant differences of mir-133 copies during culture development might indicate a different role in fish compared with mammals. We have also found signs of sub-functionalization of mir-499 paralogues after electrostimulation, with omy-mir-499b copies more responsive to electrical signals.


Assuntos
MicroRNAs/metabolismo , Mioblastos Esqueléticos/fisiologia , Oncorhynchus mykiss , Animais , Técnicas de Cultura de Células/métodos , Desenvolvimento Muscular , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Mioblastos Esqueléticos/metabolismo
3.
Am J Physiol Regul Integr Comp Physiol ; 318(2): R360-R368, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31850817

RESUMO

We examined molecular mechanisms that were altered during rapid soleus (type I fiber-dominant) and plantaris (type II fiber-dominant) hypertrophy in rats. Twelve Wistar rats (3.5 mo old; 6 female, 6 male) were subjected to surgical right-leg soleus and plantaris dual overload [synergist ablation (SA)], and sham surgeries were performed on left legs (CTL). At 14 days after surgery, the muscles were dissected. Plantaris mass was 27% greater in the SA than CTL leg (P < 0.001), soleus mass was 13% greater in the SA than CTL leg (P < 0.001), and plantaris mass was higher than soleus mass in the SA leg (P = 0.001). Plantaris total RNA concentrations and estimated total RNA levels (suggestive of ribosome density) were 19% and 47% greater in the SA than CTL leg (P < 0.05), protein synthesis levels were 64% greater in the SA than CTL leg (P = 0.038), and satellite cell number per fiber was 60% greater in the SA than CTL leg (P = 0.003); no differences in these metrics were observed between soleus SA and CTL legs. Plantaris, as well as soleus, 20S proteasome activity was lower in the SA than CTL leg (P < 0.05), although the degree of downregulation was greater in the plantaris than soleus muscle (-63% vs. -20%, P = 0.001). These data suggest that early-phase plantaris hypertrophy occurs more rapidly than soleus hypertrophy, which coincided with greater increases in ribosome biogenesis, protein synthesis, and satellite cell density, as well as greater decrements in 20S proteasome activity, in the plantaris muscle.


Assuntos
Técnicas de Ablação , Proliferação de Células , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/patologia , Músculo Esquelético/patologia , Músculo Esquelético/cirurgia , Células Satélites de Músculo Esquelético/patologia , Animais , Feminino , Hipertrofia , Masculino , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , RNA/metabolismo , Ratos Wistar , Ribossomos/metabolismo , Células Satélites de Músculo Esquelético/metabolismo , Fatores Sexuais , Fatores de Tempo
4.
Am J Physiol Cell Physiol ; 318(2): C422-C429, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31875694

RESUMO

Aerobic exercise capacity is critical to bodily health. As a model to investigate the mechanisms that determine health and disease, we employed low (LCR) and high (HCR) capacity running rat models selectively bred to concentrate the genes responsible for divergent aerobic running capacity. To investigate the skeletal muscle contribution to this innate difference in running capacity we employed an approach combining examination of the myofilament protein composition and contractile properties of the fast fiber extensor digitorum longus (EDL) and slow fiber soleus (SOL) muscles from LCR and HCR rats. Intact muscle force experiments demonstrate that SOL, but not EDL, muscles from LCR rats exhibit a three times greater decrease in fatigued force. To investigate the mechanism of this increased fatigability in the LCR SOL muscle, we determined the myofilament protein composition and functional properties. Force-Ca2+ measurements demonstrate decreased Ca2+ sensitivity of single skinned SOL muscle fibers from LCR compared with that of HCR rats. Segregating SOL fibers into fast and slow types demonstrates that the decreased Ca2+ sensitivity in LCR SOL results from a specific decrease in slow-type SOL fiber Ca2+ sensitivity such that it was similar to that of fast-type fibers. These results identify that the altered myofilament contractile properties of LCR SOL slow-type fibers result in a fast muscle type Ca2+ sensitivity and the LCR muscle phenotype. Overall our findings demonstrate alterations of the myofilament proteins could contribute to fatigability of the SOL muscle and the decreased innate aerobic running performance of LCR compared with HCR rats.


Assuntos
Tolerância ao Exercício/fisiologia , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração Lenta/fisiologia , Miofibrilas/fisiologia , Condicionamento Físico Animal/fisiologia , Animais , Cálcio/metabolismo , Feminino , Masculino , Contração Muscular/fisiologia , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Miofibrilas/metabolismo , Ratos , Corrida/fisiologia
5.
Am J Physiol Endocrinol Metab ; 317(6): E984-E998, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31573845

RESUMO

Muscle is a heterogeneous tissue composed of multiple fiber types. Earlier research revealed fiber type-selective postexercise effects on insulin-stimulated glucose uptake (ISGU) from insulin-resistant rats (increased for type IIA, IIB, IIBX, and IIX, but not type I). In whole muscle from insulin-resistant rats, the exercise increase in ISGU is accompanied by an exercise increase in insulin-stimulated AS160 phosphorylation (pAS160), an ISGU-regulating protein. We hypothesized that, in insulin-resistant muscle, the fiber type-selective exercise effects on ISGU would correspond to the fiber type-selective exercise effects on pAS160. Rats were fed a 2-wk high-fat diet (HFD) and remained sedentary (SED) or exercised before epitrochlearis muscles were dissected either immediately postexercise (IPEX) or at 3 h postexercise (3hPEX) using an exercise protocol that previously revealed fiber type-selective effects on ISGU. 3hPEX muscles and SED controls were incubated ± 100µU/mL insulin. Individual myofibers were isolated and pooled on the basis of myosin heavy chain (MHC) expression, and key phosphoproteins were measured. Myofiber glycogen and MHC expression were evaluated in muscles from other SED, IPEX, and 3hPEX rats. Insulin-stimulated pAktSer473 and pAktThr308 were unaltered by exercise in all fiber types. Insulin-stimulated pAS160 was greater for 3hPEX vs. SED on at least one phosphosite (Ser588, Thr642, and/or Ser704) in type IIA, IIBX, and IIB fibers, but not in type I or IIX fibers. Both IPEX and 3hPEX glycogen were decreased versus SED in all fiber types. These results provided evidence that fiber type-specific pAS160 in insulin-resistant muscle may play a role in the previously reported fiber type-specific elevation in ISGU in some, but not all, fiber types.


Assuntos
Proteínas Ativadoras de GTPase/metabolismo , Glucose/metabolismo , Glicogênio/metabolismo , Resistência à Insulina , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/metabolismo , Condicionamento Físico Animal , Animais , Dieta Hiperlipídica , Hexoquinase , Cadeias Pesadas de Miosina/metabolismo , Fosforilação , Ratos , Comportamento Sedentário
6.
Am J Physiol Cell Physiol ; 317(6): C1143-C1152, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31532715

RESUMO

Stretch activation (SA) is a delayed increase in force following a rapid muscle length increase. SA is best known for its role in asynchronous insect flight muscle, where it has replaced calcium's typical role of modulating muscle force levels during a contraction cycle. SA also occurs in mammalian skeletal muscle but has previously been thought to be too low in magnitude, relative to calcium-activated (CA) force, to be a significant contributor to force generation during locomotion. To test this supposition, we compared SA and CA force at different Pi concentrations (0-16 mM) in skinned mouse soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscle fibers. CA isometric force decreased similarly in both muscles with increasing Pi, as expected. SA force decreased with Pi in EDL (40%), leaving the SA to CA force ratio relatively constant across Pi concentrations (17-25%). In contrast, SA force increased in soleus (42%), causing a quadrupling of the SA to CA force ratio, from 11% at 0 mM Pi to 43% at 16 mM Pi, showing that SA is a significant force modulator in slow-twitch mammalian fibers. This modulation would be most prominent during prolonged muscle use, which increases Pi concentration and impairs calcium cycling. Based upon our previous Drosophila myosin isoform studies and this work, we propose that in slow-twitch fibers a rapid stretch in the presence of Pi reverses myosin's power stroke, enabling quick rebinding to actin and enhanced force production, while in fast-twitch fibers, stretch and Pi cause myosin to detach from actin.


Assuntos
Actinas/genética , Contração Isométrica/efeitos dos fármacos , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Miosinas/genética , Fosfatos/farmacologia , Actinas/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Fenômenos Biomecânicos , Cálcio/metabolismo , Drosophila melanogaster/fisiologia , Feminino , Expressão Gênica , Contração Isométrica/fisiologia , Mecanotransdução Celular , Camundongos , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Miosinas/metabolismo , Técnicas de Cultura de Tecidos
7.
Am J Physiol Heart Circ Physiol ; 317(2): H434-H444, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31225988

RESUMO

Exercise intolerance is a primary symptom of heart failure (HF); however, the specific contribution of central and peripheral factors to this intolerance is not well described. The hyperbolic relationship between exercise intensity and time to exhaustion (speed-duration relationship) defines exercise tolerance but is underused in HF. We tested the hypotheses that critical speed (CS) would be reduced in HF, resting central functional measurements would correlate with CS, and the greatest HF-induced peripheral dysfunction would occur in more oxidative muscle. Multiple treadmill-constant speed runs to exhaustion were used to quantify CS and D' (distance coverable above CS) in healthy control (Con) and HF rats. Central function was determined via left ventricular (LV) Doppler echocardiography [fractional shortening (FS)] and a micromanometer-tipped catheter [LV end-diastolic pressure (LVEDP)]. Peripheral O2 delivery-to-utilization matching was determined via phosphorescence quenching (interstitial Po2, Po2 is) in the soleus and white gastrocnemius during electrically induced twitch contractions (1 Hz, 8V). CS was lower in HF compared with Con (37 ± 1 vs. 44 ± 1 m/min, P < 0.001), but D' was not different (77 ± 8 vs. 69 ± 13 m, P = 0.6). HF reduced FS (23 ± 2 vs. 47 ± 2%, P < 0.001) and increased LVEDP (15 ± 1 vs. 7 ± 1 mmHg, P < 0.001). CS was related to FS (r = 0.72, P = 0.045) and LVEDP (r = -0.75, P = 0.02) only in HF. HF reduced soleus Po2 is at rest and during contractions (both P < 0.01) but had no effect on white gastrocnemius Po2 is (P > 0.05). We show in HF rats that decrements in central cardiac function relate directly with impaired exercise tolerance (i.e., CS) and that this compromised exercise tolerance is likely due to reduced perfusive and diffusive O2 delivery to oxidative muscles.NEW & NOTEWORTHY We show that critical speed (CS), which defines the upper boundary of sustainable activity, can be resolved in heart failure (HF) animals and is diminished compared with controls. Central cardiac function is strongly related with CS in the HF animals, but not controls. Skeletal muscle O2 delivery-to-utilization dysfunction is evident in the more oxidative, but not glycolytic, muscles of HF rats and is explained, in part, by reduced nitric oxide bioavailability.


Assuntos
Tolerância ao Exercício , Insuficiência Cardíaca/fisiopatologia , Contração Muscular , Músculo Esquelético/fisiopatologia , Volume Sistólico , Função Ventricular Esquerda , Animais , Cateterismo Cardíaco , Modelos Animais de Doenças , Ecocardiografia Doppler , Feminino , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/metabolismo , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/metabolismo , Infarto do Miocárdio/complicações , Infarto do Miocárdio/fisiopatologia , Óxido Nítrico/metabolismo , Oxirredução , Consumo de Oxigênio , Ratos Sprague-Dawley , Corrida , Fatores de Tempo , Pressão Ventricular
8.
Pflugers Arch ; 471(7): 971-982, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31093758

RESUMO

The relationship between the extracellular signal-regulated kinase 1 and 2 (ERK1/2), one of the mitogen-activated protein kinases (MAPKs), and mammalian skeletal muscle fiber phenotype is unclear. We looked at this relationship in three in vivo conditions in male Wistar rats. First, the levels of phosphorylated (active) ERK1/2 protein were closely associated with the fiber type composition of sedentary rat hindlimb muscles: highest in the superficial portion of the gastrocnemius (100% fast fibers), lower in the plantaris (~ 80% fast fibers), and lowest in the soleus (~ 15% fast fibers). Second, during growth, there was a gradual decrease in the percentage of fast fibers from 40% at 3 weeks to 1.5% at 65 weeks and a concomitant gradual decrease in the levels of phosphorylated ERK1/2 in the soleus muscle. Third, sciatic nerve denervation induced a significant decrease in the weight of both the soleus and plantaris, but a slow-to-fast fiber type shift and increase in phosphorylated ERK1/2 protein were observed only in the soleus. Although only a few fast and fast + slow hybrid fibers of the denervated soleus muscle reacted positively to the anti-phosphorylated ERK1/2 antibody by immuno-histochemical analysis, our results suggest that the phosphorylated form of ERK1/2 seems to be closely related to the fast fiber phenotype program. Further evidence for this relationship was provided by the observation that several slow fiber phenotype-specific proteins, i.e., Hsp72, Hsp60, and PGC-1, changed in the opposite direction of the levels of phosphorylated ERK1/2 protein.


Assuntos
Membro Posterior/metabolismo , Membro Posterior/fisiologia , Sistema de Sinalização das MAP Quinases/fisiologia , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Rápida/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Animais , Masculino , Fibras Musculares de Contração Lenta/metabolismo , Fibras Musculares de Contração Lenta/fisiologia , Atrofia Muscular/metabolismo , Atrofia Muscular/fisiopatologia , Fenótipo , Fosforilação/efeitos dos fármacos , Ratos , Ratos Wistar
9.
Eur J Orthop Surg Traumatol ; 29(7): 1539-1547, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31111314

RESUMO

Mangled extremities were classically managed by amputation. But over the past few decades, with the advancement in surgical techniques, an increased number of limb salvages have been possible. As muscles usually get damaged in such grievous injuries, a thorough understanding of muscle regeneration may give a better insight into muscle healing in these injuries. Muscles are composed of slow and fast fibers which can be represented by slow and fast myosin, respectively. There are some animal studies which reported differential regeneration of slow and fast muscle fibers during muscle healing. We conducted this pilot study to find out whether the same holds true for muscle healing in mangled extremities also. This pilot study is designed in 15 patients with lower limb mangled extremities presenting to trauma center of PGIMER, Chandigarh, who were operated within 24 h of injury to see whether muscle healing in mangled extremities follows the same pattern. Biopsies were taken during initial surgery conducted within 24 h of injury and on the 7th day of injury when patient was posted again for secondary wound closure procedure or revision amputation. The biopsy samples were subjected to histopathological and immunohistochemistry examination using antibodies against fast and slow myosin. We found that the regenerating muscle fibers in the biopsy sample taken on the 7th day of injury showed only slow muscle fibers with the absence of fast muscle fibers when compared with the initial biopsy results showing differential regeneration of slow muscle fibers.


Assuntos
Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Miosinas/metabolismo , Regeneração , Ferimentos e Lesões/metabolismo , Ferimentos e Lesões/patologia , Biomarcadores/metabolismo , Biópsia , Humanos , Extremidade Inferior/lesões , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração Lenta/patologia , Fibras Musculares de Contração Lenta/fisiologia , Músculo Esquelético/lesões , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Projetos Piloto , Estudos Prospectivos , Ferimentos e Lesões/cirurgia
10.
Endocrinology ; 160(5): 1205-1222, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30951174

RESUMO

The type 2 iodothyronine-deiodinase (D2) enzyme converts T4 to T3, and mice deficient in this enzyme [D2 knockout (D2KO) mice] have decreased T3 derived from T4 in skeletal muscle despite normal circulating T3 levels. Because slow skeletal muscle is particularly susceptible to changes in T3 levels, we expected D2 inactivation to result in more pronounced slow-muscle characteristics in the soleus muscle, mirroring hypothyroidism. However, ex vivo studies of D2KO soleus revealed higher rates of twitch contraction and relaxation and reduced resistance to fatigue. Immunostaining of D2KO soleus showed that these properties were associated with changes in muscle fiber type composition, including a marked increase in the number of fast, glycolytic type IIB fibers. D2KO soleus muscle fibers had a larger cross-sectional area, and this correlated with increased myonuclear accretion in myotubes formed from D2KO skeletal muscle precursor cells differentiated in vitro. Consistent with our functional findings, D2KO soleus gene expression was markedly different from that in hypothyroid wild-type (WT) mice. Comparison of gene expression between euthyroid WT and D2KO mice indicated that PGC-1α, a T3-dependent regulator of slow muscle fiber type, was decreased by ∼50% in D2KO soleus. Disruption of Dio2 in the C2C12 myoblast cell line led to a significant decrease in PGC-1α expression and a faster muscle phenotype upon differentiation. These results indicate that D2 loss leads to significant changes in soleus contractile function and fiber type composition that are inconsistent with local hypothyroidism and suggest that reduced levels of PCG-1α may contribute to the observed phenotypical changes.


Assuntos
Iodeto Peroxidase/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Mioblastos/metabolismo , Animais , Linhagem Celular , Expressão Gênica , Iodeto Peroxidase/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Contração Muscular/genética , Contração Muscular/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Mioblastos/citologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Tiroxina/metabolismo , Tri-Iodotironina/metabolismo
11.
Mol Cell Biochem ; 458(1-2): 79-87, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30993497

RESUMO

Although exercise affects the function and structure of skeletal muscle, our knowledge regarding the biomedical alterations induced by different intensities of exercise is incomplete. Here we report on the changes in biomarker levels and myofiber constitution in the rat soleus muscle induced by exercise intensity. Male adult rats at 7 weeks of age were divided into 3 groups by exercise intensity, which was set based on the accumulated lactate levels in the blood using a treadmill: stationary control (0 m/min), aerobic exercise (15 m/min), and anaerobic exercise (25 m/min). The rats underwent 30 min/day treadmill training at different exercise intensities for 14 days. Immediately after the last training session, the soleus muscle was dissected out in order to measure the muscle biomarker levels and evaluate the changes in the myofibers. The mRNA expression of citrate synthase, glucose-6-phosphate dehydrogenase, and Myo D increased with aerobic exercise, while the mRNA expression of myosin heavy-chain I and Myo D increased in anaerobic exercise. These results suggest that muscle biomarkers can be used as parameters for the muscle adaptation process in aerobic/anaerobic exercise. Interestingly, by 14 days after the anaerobic exercise, the number of type II (fast-twitch) myofibers had decreased by about 20%. Furthermore, many macrophages and regenerated fibers were observed in addition to the injured fibers 14 days after the anaerobic exercise. Constitutional changes in myofibers due to damage incurred during anaerobic exercise are necessary for at least about 2 weeks. These results indicate that the changes in the biomarker levels and myofiber constitution by exercise intensity are extremely important for understanding the metabolic adaptations of skeletal muscle during physical exercise.


Assuntos
Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Proteínas Musculares/metabolismo , Condicionamento Físico Animal , Animais , Biomarcadores/metabolismo , Masculino , Ratos , Ratos Wistar , Fatores de Tempo
12.
Anim Sci J ; 90(6): 781-789, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30938015

RESUMO

Skeletal muscle fiber is largely classified into two types: type 1 (slow-twitch) and type 2 (fast-twitch) fibers. Meat quality and composition of fiber types are thought to be closely related. Previous research showed that overexpression of constitutively active peroxisome proliferator-activated receptor (PPAR)δ, a nuclear receptor present in skeletal muscle, increased type 1 fibers in mice. In this study, we found that hexane extracts of Yamabushitake mushroom (Hericium erinaceus) showed PPARδ agonistic activity in vitro. Eight-week-old C57BL/6J mice were fed a diet supplemented with 5% (w/w) freeze-dried Yamabushitake mushroom for 24 hr. After the treatment period, the extensor digitorum longus (EDL) muscles were excised. The Yamabushitake-supplemented diet up-regulated the PPARδ target genes Pdk4 and Ucp3 in mouse skeletal muscles in vivo. Furthermore, feeding the Yamabushitake-supplemented diet to mice for 8 weeks resulted in a significant increase in muscle endurance. These results indicate that Yamabushitake mushroom contains PPARδ agonistic ligands and that dietary intake of Yamabushitake mushroom could activate PPARδ in skeletal muscle of mice. Unexpectedly, we observed no significant alterations in composition of muscle fiber types between the mice fed control and Yamabushitake-supplemented diets.


Assuntos
Agaricales/química , Suplementos Nutricionais , Força Muscular , Músculo Esquelético/metabolismo , PPAR delta/agonistas , Extratos Vegetais/farmacologia , Animais , Hexanos , Ligantes , Masculino , Camundongos Endogâmicos C57BL , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , PPAR delta/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Quinase Piruvato Desidrogenase (Transferência de Acetil) , Fatores de Tempo , Proteína Desacopladora 3/genética , Proteína Desacopladora 3/metabolismo , Regulação para Cima/efeitos dos fármacos
13.
Am J Physiol Endocrinol Metab ; 316(5): E967-E976, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30912963

RESUMO

Alcoholic myopathy is characterized by the reduction in cross-sectional area (CSA) of muscle fibers and impaired anabolic signaling. The goal of the current study was to investigate the causes and compare the changes in CSA and fiber type composition with the modifications of anabolic and catabolic signaling pathways at the early stages of chronic alcohol consumption in women. Skeletal muscle samples from 5 female patients with alcohol abuse (AL; 43 ± 5 yr old; alcohol abuse duration 5,6 ± 0,6 yr) were compared with the muscle from the control group of 8 healthy women (C; 35 ± 4 yr old). The average daily dose of alcohol consumption was 110 ± 10 ml of pure ethanol. In women patients, a significant decrease in CSA of type I and II muscle fibers, titin and nebulin content, plasma IGF-1 level and total IRS-1, p-Akt and p-4E-BP1 in vastus lateralis was found in comparison with the control group. The p-AMPK level was found to be increased versus the control group. In women patients with chronic alcoholic myopathy 1) both fast and slow muscle fibers are subjected to atrophy; 2) impairments in IGF-I-dependent signaling and pathways controlling translation initiation (AMPK/mTOR/4E-BP1), but not translation elongation, are observed; 3) the level of calpain-1 and ubiquitinated proteins increases, unlike E3 ligases content.


Assuntos
Transtornos Induzidos por Álcool/metabolismo , Alcoolismo/metabolismo , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Doenças Musculares/metabolismo , Músculo Quadríceps/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Adenilato Quinase/metabolismo , Adulto , Transtornos Induzidos por Álcool/patologia , Estudos de Casos e Controles , Proteínas de Ciclo Celular/metabolismo , Conectina/metabolismo , Feminino , Humanos , Proteínas Substratos do Receptor de Insulina/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Pessoa de Meia-Idade , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/patologia , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Doenças Musculares/patologia , Tamanho do Órgão , Fosfoproteínas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Músculo Quadríceps/patologia , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo
14.
Am J Physiol Endocrinol Metab ; 316(5): E837-E851, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30835507

RESUMO

Earlier research using muscle tissue demonstrated that postexercise elevation in insulin-stimulated glucose uptake (ISGU) occurs concomitant with greater insulin-stimulated Akt substrate of 160 kDa (AS160) phosphorylation (pAS160) on sites that regulate ISGU. Because skeletal muscle is a heterogeneous tissue, we previously isolated myofibers from rat epitrochlearis to assess fiber type-selective ISGU. Exercise induced greater ISGU in type I, IIA, IIB, and IIBX but not IIX fibers. This study tested if exercise effects on pAS160 correspond with previously published fiber type-selective exercise effects on ISGU. Rats were studied immediately postexercise (IPEX) or 3.5 h postexercise (3.5hPEX) with time-matched sedentary controls. Myofibers dissected from the IPEX experiment were analyzed for fiber type (myosin heavy chain isoform expression) and key phosphoproteins. Isolated muscles from the 3.5hPEX experiment were incubated with or without insulin. Myofibers (3.5hPEX) were analyzed for fiber type, key phosphoproteins, and GLUT4 protein abundance. We hypothesized that insulin-stimulated pAS160 at 3.5hPEX would exceed sedentary controls only in fiber types characterized by greater ISGU postexercise. Values for phosphorylation of AMP-activated kinase substrates (acetyl CoA carboxylaseSer79 and AS160Ser704) from IPEX muscles exceeded sedentary values in each fiber type, suggesting exercise recruitment of all fiber types. Values for pAS160Thr642 and pAS160Ser704 from insulin-stimulated muscles 3.5hPEX exceeded sedentary values for type I, IIA, IIB, and IIBX but not IIX fibers. GLUT4 abundance was unaltered 3.5hPEX in any fiber type. These results advanced understanding of exercise-induced insulin sensitization by providing compelling support for the hypothesis that enhanced insulin-stimulated phosphorylation of AS160 is linked to elevated ISGU postexercise at a fiber type-specific level independent of altered GLUT4 expression.


Assuntos
Proteínas Ativadoras de GTPase/metabolismo , Glucose/metabolismo , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Condicionamento Físico Animal , Animais , Proteínas Ativadoras de GTPase/efeitos dos fármacos , Transportador de Glucose Tipo 4/metabolismo , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Fosforilação , Ratos
15.
Int J Sports Med ; 40(4): 253-262, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30836391

RESUMO

Consequences of running mountain races on muscle damage were investigated by analysing serum muscle enzymes and fibre-type-specific sarcomere proteins. We studied 10 trained amateur and 6 highly trained runners who ran a 35 km and 55 km mountain trail race (MTR), respectively. Levels of creatine kinase (CK), CK-MB isoform (CK-MB), sarcomeric mitochondrial CK (sMtCK), transaminases (AST and ALT), cardiac troponin I (cTnI) and fast (FM) and slow myosin (SM) isoforms, were assessed before, 1 h, 24 h and 48 h after the beginning of MTR. Significant SM increases were found at 24 h in the 55 km group. Levels of CK, CK-MB, AST and cTnI were significantly elevated in both groups following MTR, but in the 55 km group they tended to stabilize in at 48 h. Using pooled data, time-independent serum peaks of SM and CK-MB were significantly correlated. Moreover, concentration of sMtCK was significantly elevated at 1 and 24 h after the race in the 35 km group. Although training volume could confer protection on the mitochondria, the increase in serum CK-MB and SM in the 55 km group might be related to damage to the contractile apparatus type I fibres. Competing in long-distance MTRs might be related to deeper type I muscle fibre damage, even in highly trained individuals.


Assuntos
Mitocôndrias Musculares/metabolismo , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/lesões , Músculo Esquelético/metabolismo , Resistência Física/fisiologia , Corrida/lesões , Adulto , Alanina Transaminase/metabolismo , Aspartato Aminotransferases/metabolismo , Biomarcadores/sangue , Biomarcadores/metabolismo , Comportamento Competitivo/fisiologia , Creatina Quinase/sangue , Creatina Quinase Forma MB/sangue , Humanos , Masculino , Mitocôndrias Musculares/enzimologia , Fibras Musculares de Contração Rápida/enzimologia , Fibras Musculares de Contração Lenta/enzimologia , Miosinas/metabolismo , Condicionamento Físico Humano , Isoformas de Proteínas/metabolismo , Sarcômeros/enzimologia , Troponina I/metabolismo
16.
Am J Physiol Regul Integr Comp Physiol ; 316(5): R584-R593, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30789789

RESUMO

An impaired capacity of muscle to regenerate after critical illness results in long-term functional disability. We previously described in a long-term rat peritonitis model that gastrocnemius displays near-normal histology whereas soleus demonstrates a necrotizing phenotype. We thus investigated the link between the necrotizing phenotype of critical illness myopathy and proteasome activity in these two limb muscles. We studied male Wistar rats that underwent an intraperitoneal injection of the fungal cell wall constituent zymosan or n-saline as a sham-treated control. Rats (n = 74) were killed at 2, 7, and 14 days postintervention with gastrocnemius and soleus muscle removed and studied ex vivo. Zymosan-treated animals displayed an initial reduction of body weight but a persistent decrease in mass of both lower hindlimb muscles. Zymosan increased chymotrypsin- and trypsin-like proteasome activities in gastrocnemius at days 2 and 7 but in soleus at day 2 only. Activated caspases-3 and -9, polyubiquitin proteins, and 14-kDa fragments of myofibrillar actin (proteasome substrates) remained persistently increased from day 2 to day 14 in soleus but not in gastrocnemius. These results suggest that a relative proteasome deficiency in soleus is associated with a necrotizing phenotype during long-term critical illness. Rescuing proteasome clearance may offer a potential therapeutic option to prevent long-term functional disability in critically ill patients.


Assuntos
Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Proteínas Musculares/metabolismo , Peritonite/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Regeneração , Animais , Autofagia , Estado Terminal , Modelos Animais de Doenças , Membro Posterior , Masculino , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/patologia , Necrose , Peritonite/patologia , Peritonite/fisiopatologia , Fenótipo , Proteólise , Ratos Wistar , Fatores de Tempo , Ubiquitinação
17.
J Oleo Sci ; 68(2): 141-148, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30713267

RESUMO

Alaska pollack protein (APP) was previously shown to reduce serum triacylglycerol and the atherogenic index and significantly increase gastrocnemius muscle mass in rats. To determine which myofibers are involved in this observed hypertrophy, we stained the gastrocnemius muscle with fast and slow fiber-specific antibodies and measured the muscle fiber diameter. We observed muscle hypertrophy in both the fast and slow fibers of APP-fed rats. Although muscle hypertrophy leads to drastic lipid changes, the amount of lipids did not differ significantly between casein-fed and APP-fed rats. To determine the lipid changes at the molecular species level and their localization, we performed matrix-assisted laser desorption/ionization mass spectrometry imaging to visualize lipids in the gastrocnemius muscles. We determined that lipid molecules were significantly changed due to APP feeding. Thus, APP feeding changes muscle lipid metabolism, and these metabolic changes might be related to hypertrophy.


Assuntos
Proteínas de Peixes/administração & dosagem , Hipertrofia , Metabolismo dos Lipídeos , Lipídeos/análise , Músculo Esquelético/metabolismo , Animais , Gadiformes , Masculino , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/anormalidades , Ratos Sprague-Dawley , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
18.
Respir Res ; 20(1): 31, 2019 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-30764835

RESUMO

BACKGROUND: The pathophysiology of obstruction and swallowing dysfunction in snores and sleep apnea patients remains unclear. Neuropathy and to some extent myopathy have been suggested as contributing causes. Recently we reported an absence and an abnormal isoform of two cytoskeletal proteins, desmin, and dystrophin, in upper airway muscles of healthy humans. These cytoskeletal proteins are considered vital for muscle function. We aimed to investigate for muscle cytoskeletal abnormalities in upper airways and its association with swallowing dysfunction and severity of sleep apnea. METHODS: Cytoskeletal proteins desmin and dystrophin were morphologically evaluated in the uvula muscle of 22 patients undergoing soft palate surgery due to snoring and sleep apnea and in 10 healthy controls. The muscles were analysed with immunohistochemical methods, and swallowing function was assessed using videoradiography. RESULTS: Desmin displayed a disorganized pattern in 21 ± 13% of the muscle fibres in patients, while these fibers were not present in controls. Muscle fibres lacking desmin were present in both patients and controls, but the proportion was higher in patients (25 ± 12% vs. 14 ± 7%, p = 0.009). The overall desmin abnormalities were significantly more frequent in patients than in controls (46 ± 18% vs. 14 ± 7%, p < 0.001). In patients, the C-terminus of the dystrophin molecule was absent in 19 ± 18% of the desmin-abnormal muscle fibres. Patients with swallowing dysfunction had 55 ± 10% desmin-abnormal muscle fibres vs. 22 ± 6% in patients without swallowing dysfunction, p = 0.002. CONCLUSION: Cytoskeletal abnormalities in soft palate muscles most likely contribute to pharyngeal dysfunction in snorers and sleep apnea patients. Plausible causes for the presence of these abnormalities is traumatic snoring vibrations, tissue stretch or muscle overload.


Assuntos
Desmina/metabolismo , Distrofina/metabolismo , Músculos Respiratórios/metabolismo , Síndromes da Apneia do Sono/metabolismo , Ronco/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Citoesqueleto/patologia , Transtornos de Deglutição/metabolismo , Transtornos de Deglutição/patologia , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/metabolismo , Fibras Musculares de Contração Lenta/patologia , Palato Mole/metabolismo , Palato Mole/patologia , Músculos Respiratórios/patologia , Síndromes da Apneia do Sono/patologia , Ronco/patologia , Úvula/metabolismo , Úvula/patologia , Adulto Jovem
19.
Anim Sci J ; 90(4): 604-609, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30811817

RESUMO

Free amino acids are important components of tastants and flavor precursors in meat. To clarify the correlation between muscle fiber type and free amino acids, we determined the concentrations of various free amino acids and dipeptides in samples of different muscle tissues (n = 21), collected from 26-month-old Japanese Black steers (n = 3) at 2 days postmortem. The proportions of the myosin heavy chain (MyHC), slow (MyHC1) and fast (MyHC2) isoforms were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The contents of free amino acids and dipeptides were measured by high performance liquid chromatography (HPLC). The MyHC isoform composition varied among the tissue samples. The MyHC1 proportion ranged from 6.9% ± 3.9% to 83.3% ± 16.7%. We confirmed that there was a strong positive correlation between MyHC1 composition and total free amino acid concentrations, including those for two dipeptides. Among the 31 measured free amino acids and dipeptides, 11 showed significant positive correlations and five showed significant negative correlations with MyHC1 composition. These results suggest that a high MyHC1 content induces high free amino acid contents in bovine muscles possibly because of greater oxidative metabolism. This high level of free amino acids could contribute to the intense flavor of meat that is rich in slow-twitch fibers.


Assuntos
Aminoácidos/análise , Aminoácidos/metabolismo , Análise de Alimentos , Qualidade dos Alimentos , Fibras Musculares de Contração Lenta/metabolismo , Músculo Esquelético/metabolismo , Carne Vermelha/análise , Animais , Bovinos , Dipeptídeos/análise , Dipeptídeos/metabolismo , Masculino , Cadeias Pesadas de Miosina/análise , Cadeias Pesadas de Miosina/metabolismo , Isoformas de Proteínas/análise , Isoformas de Proteínas/metabolismo
20.
Am J Physiol Endocrinol Metab ; 316(5): E695-E706, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30753114

RESUMO

Insulin-stimulated glucose uptake (GU) by skeletal muscle is enhanced several hours after acute exercise in rats with normal or reduced insulin sensitivity. Skeletal muscle is composed of multiple fiber types, but exercise's effect on fiber type-specific insulin-stimulated GU in insulin-resistant muscle was previously unknown. Male rats were fed a high-fat diet (HFD; 2 wk) and were either sedentary (SED) or exercised (2-h exercise). Other, low-fat diet-fed (LFD) rats remained SED. Rats were studied immediately postexercise (IPEX) or 3 h postexercise (3hPEX). Epitrochlearis muscles from IPEX rats were incubated in 2-deoxy-[3H]glucose (2-[3H]DG) without insulin. Epitrochlearis muscles from 3hPEX rats were incubated with 2-[3H]DG ± 100 µU/ml insulin. After single fiber isolation, GU and fiber type were determined. Glycogen and lipid droplets (LDs) were assessed histochemically. GLUT4 abundance was determined by immunoblotting. In HFD-SED vs. LFD-SED rats, insulin-stimulated GU was decreased in type IIB, IIX, IIAX, and IIBX fibers. Insulin-independent GU IPEX was increased and glycogen content was decreased in all fiber types (types I, IIA, IIB, IIX, IIAX, and IIBX). Exercise by HFD-fed rats enhanced insulin-stimulated GU in all fiber types except type I. Single fiber analyses enabled discovery of striking fiber type-specific differences in HFD and exercise effects on insulin-stimulated GU. The fiber type-specific differences in insulin-stimulated GU postexercise in insulin-resistant muscle were not attributable to a lack of fiber recruitment, as indirectly evidenced by insulin-independent GU and glycogen IPEX, differences in multiple LD indexes, or altered GLUT4 abundance, implicating fiber type-selective differences in the cellular processes responsible for postexercise enhancement of insulin-mediated GLUT4 translocation.


Assuntos
Glucose/metabolismo , Resistência à Insulina , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Animais , Dieta Hiperlipídica , Transportador de Glucose Tipo 4/metabolismo , Glicogênio/metabolismo , Insulina/farmacologia , Gotículas Lipídicas/metabolismo , Masculino , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Condicionamento Físico Animal , Ratos , Ratos Wistar , Comportamento Sedentário
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