Downhill Running Excessive Training Inhibits Hypertrophy in Mice Skeletal Muscles with Different Fiber Type Composition

2015 ◽  
Vol 231 (5) ◽  
pp. 1045-1056 ◽  
Author(s):  
Alisson L. da Rocha ◽  
Bruno C. Pereira ◽  
José R. Pauli ◽  
Claudio T. de Souza ◽  
Giovana R. Teixeira ◽  
...  
Keyword(s):  
Skeletal Muscles ◽  
Fiber Type ◽  
Fiber Type Composition ◽  
Downhill Running ◽  
Type Composition

Myosin isozyme distribution in rodent hindlimb skeletal muscle

1986 ◽  
Vol 60 (6) ◽  
pp. 1923-1931 ◽  
Author(s):  
D. B. Thomason ◽  
K. M. Baldwin ◽  
R. E. Herrick
Keyword(s):  
Atpase Activity ◽  
Light Chain ◽  
Skeletal Muscles ◽  
Fiber Type ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Fiber Type Composition ◽  
Type Composition ◽  
Myosin Isozyme ◽  
Myofibril Atpase

The purpose of this study was to examine the distribution of myosin isozymes in rodent (Rattus norvegicus) hindlimb skeletal muscles and regions of muscle known to have contrasting fiber-type composition. Muscle samples were analyzed for Ca2+-regulated myofibril adenosine triphosphatase (ATPase) activity, Ca2+-activated myosin ATPase activity, myosin isozyme profile, and myosin light chain profile. Four isozymes of myosin were identified based on native protein and light chain electrophoresis patterns: one associated primarily with slow-twitch muscle (SM) and three associated primarily with fast-twitch muscle (FM). Multiple linear regression analysis of Ca2+-regulated myofibril ATPase activity (pCA 4) vs. measured isozyme profile was used to estimate the myofibril ATPase activities of the individual isozymes (FM1 = 0.86, FM2 = 0.52, FM3 = 0.31, and SM = 0.15 mumol Pi formed . mg myofibril protein-1 . min-1 at 25 degrees C, n = 180, P less than 0.001). Differences in the native isozyme profiles and myofibril ATPase activities between muscles and muscle regions of similar fiber type composition indicate that a given fiber type may not necessarily express a single isozyme profile. These data are consistent with the hypothesis that, among rodent hindlimb skeletal muscles and inherently their motor units, a range of myosin isozyme profiles exists that may provide a broad range of mechanical expression.

scholarly journals Diversity in levels of intracellular total creatine and triglycerides in human skeletal muscles observed by1H-MRS

1999 ◽  
Vol 87 (6) ◽  
pp. 2068-2072 ◽  
Author(s):  
Jesús Rico-Sanz ◽  
E. Louise Thomas ◽  
Gabriele Jenkinson ◽  
Šárka Mierisová ◽  
Richard Iles ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Fiber Type ◽  
Resonance Spectroscopy ◽  
Fiber Type Composition ◽  
Type Composition ◽  
Total Creatine ◽  
Human Skeletal Muscles

We used1H-magnetic resonance spectroscopy to noninvasively determine total creatine (TCr), choline-containing compounds (Cho), and intracellular (IT) and extracellular (between-muscle fibers) triglycerides (ET) in three human skeletal muscles. Subjects' ( n = 15 men) TCr concentrations in soleus [Sol; 100.2 ± 8.3 (SE) mmol/kg dry wt] were lower ( P < 0.05) than those in gastrocnemius (Gast; 125.3 ± 9.2 mmol/kg dry wt) and tibialis anterior (TA; 123.7 ± 8.8 mmol/kg dry wt). The Cho levels in Sol (35.8 ± 3.6 mmol/kg dry wt) and Gast (28.5 ± 3.5 mmol/kg dry wt) were higher ( P < 0.001 and P < 0.01, respectively) compared with TA (13.6 ± 2.4 mmol/kg dry wt). The IT values were found to be 44.8 ± 4.6 and 36.5 ± 4.2 mmol/kg dry wt in Sol and Gast, respectively. The IT values of TA (24.5 ± 4.5 mmol/kg dry wt) were lower than those of Sol ( P < 0.01) and Gast ( P < 0.05). There were no differences in ET [116.0 ± 11.2 (Sol), 119.1 ± 18.5 (Gast), and 91.4 ± 19.2 mmol/kg dry wt (TA)]. It is proposed that the differences in metabolite levels may be due to the differences in fiber-type composition and deposition of metabolites due to the adaptation of different muscles during locomotion.

Fiber type composition of four hindlimb muscles of adult Fisher 344 rats

1999 ◽  
Vol 111 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Robert S. Staron ◽  
William J. Kraemer ◽  
Robert S. Hikida ◽  
Andy C. Fry ◽  
Jerry D. Murray ◽  
...  
Keyword(s):  
Fiber Type ◽  
Fiber Type Composition ◽  
Hindlimb Muscles ◽  
Type Composition

Myostatin regulates fiber-type composition of skeletal muscle by regulating MEF2 and MyoD gene expression

2009 ◽  
Vol 296 (3) ◽  
pp. C525-C534 ◽  
Author(s):  
Alex Hennebry ◽  
Carole Berry ◽  
Victoria Siriett ◽  
Paul O'Callaghan ◽  
Linda Chau ◽  
...  
Keyword(s):  
Growth Factor ◽  
Target Genes ◽  
Fiber Type ◽  
Fiber Formation ◽  
Type I ◽  
Mobility Shift ◽  
Enhancer Activity ◽  
Fiber Type Composition ◽  
Nuclear Extracts ◽  
Type Composition

Myostatin (Mstn) is a secreted growth factor belonging to the tranforming growth factor (TGF)-β superfamily. Inactivation of murine Mstn by gene targeting, or natural mutation of bovine or human Mstn, induces the double muscling (DM) phenotype. In DM cattle, Mstn deficiency increases fast glycolytic (type IIB) fiber formation in the biceps femoris (BF) muscle. Using Mstn null (−/−) mice, we suggest a possible mechanism behind Mstn-mediated fiber-type diversity. Histological analysis revealed increased type IIB fibers with a concomitant decrease in type IIA and type I fibers in the Mstn−/−tibialis anterior and BF muscle. Functional electrical stimulation of Mstn−/−BF revealed increased fatigue susceptibility, supporting increased type IIB fiber content. Given the role of myocyte enhancer factor 2 (MEF2) in oxidative type I fiber formation, MEF2 levels in Mstn−/−tissue were quantified. Results revealed reduced MEF2C protein in Mstn−/−muscle and myoblast nuclear extracts. Reduced MEF2-DNA complex was also observed in electrophoretic mobility-shift assay using Mstn−/−nuclear extracts. Furthermore, reduced expression of MEF2 downstream target genes MLC1F and calcineurin were found in Mstn−/−muscle. Conversely, Mstn addition was sufficient to directly upregulate MLC promoter-enhancer activity in cultured myoblasts. Since high MyoD levels are seen in fast fibers, we analyzed MyoD levels in the muscle. In contrast to MEF2C, MyoD levels were increased in Mstn−/−muscle. Together, these results suggest that while Mstn positively regulates MEF2C levels, it negatively regulates MyoD expression in muscle. We propose that Mstn could regulate fiber-type composition by regulating the expression of MEF2C and MyoD during myogenesis.

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