The Effect of Severe Dietary Protein Restriction on Skeletal Muscle Fiber Number, Area and Composition in Weanling Rats

1985 ◽  
Vol 61 (2) ◽  
pp. 416-422 ◽  
Author(s):  
B. F. Timson ◽  
G. A. Dudenhoeffer
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Dietary Protein ◽  
Protein Restriction ◽  
Skeletal Muscle Fiber ◽  
Dietary Protein Restriction ◽  
Weanling Rats ◽  
Fiber Number ◽  
Muscle Fiber Number

Estimation of skeletal muscle fiber number by mean fiber dry weight

1984 ◽  
Vol 56 (1) ◽  
pp. 244-247
Author(s):  
B. F. Timson ◽  
G. A. Dudenhoeffer
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Biceps Brachii ◽  
Estimation Method ◽  
Dry Weight ◽  
Skeletal Muscle Fiber ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Nitric Acid Digestion ◽  
Muscle Fiber Number

The purpose of this study was to determine whether skeletal muscle fiber number could be accurately estimated by the determination of mean fiber dry weight (MFD) and total muscle dry weight. The muscles studied were the soleus, plantaris, gastrocnemius, extensor digitorum longus, tibialis anterior, and biceps brachii of the rat, the anterior latissimus dorsi of the chicken, and the flexor carpi radialis of the cat. Bundles of fibers were carefully separated from the muscle following nitric acid digestion (ND) and placed in groups of similar length. MFD determined from 400 to 800 fibers from each group was used to estimate the number of fibers in the remainder of the group. Estimated fiber number was compared with the fiber number determined in the muscle from the contralateral limb by the ND method. No difference in fiber number was observed between the ND method and the MFD estimation method for any of the muscles used in the study. The results indicate that the MFD estimation method is an accurate and relatively rapid method of fiber number determination in skeletal muscle.

scholarly journals Mechanical overload and skeletal muscle fiber hyperplasia: a meta-analysis

1996 ◽  
Vol 81 (4) ◽  
pp. 1584-1588 ◽  
Author(s):  
George Kelley
Keyword(s):  
Skeletal Muscle ◽  
Confidence Interval ◽  
Muscle Fiber ◽  
Meta Analysis ◽  
Compensatory Hypertrophy ◽  
Skeletal Muscle Fiber ◽  
Fiber Number ◽  
Nitric Acid Digestion ◽  
Mechanical Overload ◽  
Muscle Fiber Number

Kelley, George. Mechanical overload and skeletal muscle fiber hyperplasia: a meta-analysis. J. Appl. Physiol. 81(4): 1584–1588, 1996.—With use of the meta-analytic approach, the purpose of this study was to examine the effects of mechanical overload on skeletal muscle fiber number in animals. A total of 17 studies yielding 37 data points and 360 subjects met the initial inclusion criteria: 1) “basic” research studies published in journals, 2) animals (no humans) as subjects, 3) control group included, 4) some type of mechanical overload (stretch, exercise, or compensatory hypertrophy) used to induce changes in muscle fiber number, and 5) sufficient data to accurately calculate percent changes in muscle fiber number. Across all designs and categories, statistically significant increases were found for muscle fiber number [15.00 ± 19.60% (SD), 95% confidence interval = 8.65–21.53], muscle fiber area (31.60 ± 44.30%, 95% confidence interval = 16.83–46.37), and muscle mass (90.50 ± 86.50%, 95% confidence interval = 61.59–119.34). When partitioned according to the fiber-counting technique, larger increases in muscle fiber number were found by using the histological vs. nitric acid digestion method (histological = 20.70%, nitric acid digestion = 11.10%; P = 0.14). Increases in fiber number partitioned according to species were greatest among those groups that used an avian vs. mammalian model (avian = 20.95%, mammalian = 7.97%; P = 0.07). Stretch overload yielded larger increases in muscle fiber number than did exercise and compensatory hypertrophy (stretch = 20.95%, exercise = 11.59%, compensatory hypertrophy = 5.44%; P = 0.06). No significant differences between changes in fiber number were found when data were partitioned according to type of control (intra-animal = 15.20%, between animal = 13.90%; P = 0.82) or fiber arrangement of muscle (parallel = 15.80%, pennate = 11.60%; P = 0.61). The results of this study suggest that in several animal species certain forms of mechanical overload increase muscle fiber number.

Human Skeletal Muscle Fiber Types: Delineation, Development, and Distribution

1997 ◽  
Vol 22 (4) ◽  
pp. 307-327 ◽  
Author(s):  
Robert S. Staron
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Skeletal Muscle Fiber ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Key Words Aging ◽  
Fiber Number ◽  
Human Limb

This brief review attempts to summarize a number of studies on the delineation, development, and distribution of human skeletal muscle fiber types. A total of seven fiber types can be identified in human limb and trunk musculature based on the pH stability/ability of myofibrillar adenosine triphosphatase (mATPase). For most human muscles, mATPase-based fiber types correlate with the myosin heavy chain (MHC) content. Thus, each histochemically identified fiber has a specific MHC profile. Although this categorization is useful, it must be realized that muscle fibers are highly adaptable and that innumerable fiber type transients exist. Also, some muscles contain specific MHC isoforms and/or combinations that do not permit routine mATPase-based fiber typing. Although the major populations of fast and slow are, for the most part, established shortly after birth, subtle alterations take place throughout life. These changes appear to relate to alterations in activity and/or hormonal levels, and perhaps later in life, total fiber number. Because large variations in fiber type distribution can be found within a muscle and between individuals, interpretation of data gathered from human muscle is often difficult. Key words: aging, myosin heavy chains, myogenesis, myofibrillar adenosine triphosphate

scholarly journals Maternal dietary protein restriction and excess affects offspring gene expression and methylation of non-SMC subunits of condensin I in liver and skeletal muscle

Epigenetics ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. 239-252 ◽  
Author(s):  
Simone Altmann ◽  
Eduard Murani ◽  
Manfred Schwerin ◽  
Cornelia C. Metges ◽  
Klaus Wimmers ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Dietary Protein ◽  
Protein Restriction ◽  
Dietary Protein Restriction

scholarly journals Endocrine regulation of fetal skeletal muscle growth: impact on future metabolic health

2014 ◽  
Vol 221 (2) ◽  
pp. R13-R29 ◽  
Author(s):  
Laura D Brown
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Muscle Fiber ◽  
Muscle Growth ◽  
Metabolic Health ◽  
Endocrine Regulation ◽  
Intrauterine Environment ◽  
Skeletal Muscle Growth ◽  
Fiber Number ◽  
Muscle Fiber Number

Establishing sufficient skeletal muscle mass is essential for lifelong metabolic health. The intrauterine environment is a major determinant of the muscle mass that is present during the life course of an individual, because muscle fiber number is set at the time of birth. Thus, a compromised intrauterine environment from maternal nutrient restriction or placental insufficiency that restricts muscle fiber number can have permanent effects on the amount of muscle an individual will live with. Reduced muscle mass due to fewer muscle fibers persists even after compensatory or ‘catch-up’ postnatal growth occurs. Furthermore, muscle hypertrophy can only partially compensate for this limitation in fiber number. Compelling associations link low birth weight and decreased muscle mass to future insulin resistance, which can drive the development of the metabolic syndrome and type 2 diabetes, and the risk of cardiovascular events later in life. There are gaps in knowledge about the origins of reduced muscle growth at the cellular level and how these patterns are set during fetal development. By understanding the nutrient and endocrine regulation of fetal skeletal muscle growth and development, we can direct research efforts toward improving muscle growth early in life to prevent the development of chronic metabolic diseases later in life.

scholarly journals Leucine Supplementation Does Not Restore Diminished Skeletal Muscle Satellite Cell Abundance and Myonuclear Accretion When Protein Intake Is Limiting in Neonatal Pigs

2019 ◽  
Vol 150 (1) ◽  
pp. 22-30
Author(s):  
Marko Rudar ◽  
Daniel A Columbus ◽  
Julia Steinhoff-Wagner ◽  
Agus Suryawan ◽  
Hanh V Nguyen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
G Protein ◽  
Satellite Cell ◽  
Dietary Protein ◽  
Protein Intake ◽  
Protein Restriction ◽  
Dietary Protein Restriction ◽  
Cell Abundance ◽  
Neonatal Pigs ◽  
Igf2 Expression

ABSTRACT Background Rapid growth of skeletal muscle in the neonate requires the coordination of protein deposition and myonuclear accretion. During this developmental stage, muscle protein synthesis is highly sensitive to amino acid supply, especially Leu, but we do not know if this is true for satellite cells, the source of muscle fiber myonuclei. Objective We examined whether dietary protein restriction reduces myonuclear accretion in the neonatal pig, and if any reduction in myonuclear accretion is mitigated by restoring Leu intake. Methods Neonatal pigs (1.53 ± 0.2 kg) were fitted with jugular vein and gastric catheters and fed 1 of 3 isoenergetic milk replacers every 4 h for 21 d: high protein [HP; 22.5 g protein/(kg/d); n= 8]; restricted protein [RP; 11.2 g protein/(kg/d); n= 10]; or restricted protein with Leu [RPL; 12.0 g protein/(kg/d); n= 10]. Pigs were administered 5-bromo-2’-deoxyuridine (BrdU; 15 mg/kg) intravenously every 12 h from days 6 to 8. Blood was sampled on days 6 and 21 to measure plasma Leu concentrations. On day 21, pigs were killed and the longissimus dorsi (LD) muscle was collected to measure cell morphometry, satellite cell abundance, myonuclear accretion, and insulin-like growth factor (IGF) system expression. Results Compared with HP pigs, postprandial plasma Leu concentration in RP pigs was 37% and 47% lower on days 6 and 21, respectively (P < 0.05); Leu supplementation in RPL pigs restored postprandial Leu to HP concentrations. Dietary protein restriction reduced LD myofiber cross-sectional area by 21%, satellite cell abundance by 35%, and BrdU+ myonuclear abundance by 25% (P < 0.05); Leu did not reverse these outcomes. Dietary protein restriction reduced LD muscle IGF2 expression by 60%, but not IGF1 or IGF1R expression (P < 0.05); Leu did not rescue IGF2 expression. Conclusions Satellite cell abundance and myonuclear accretion in neonatal pigs are compromised when dietary protein intake is restricted and are not restored with Leu supplementation.

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