Motoneuron and muscle fiber succinate dehydrogenase activity in control and overloaded plantaris

1991 ◽  
Vol 71 (4) ◽  
pp. 1589-1592 ◽  
Author(s):  
G. R. Chalmers ◽  
R. R. Roy ◽  
V. R. Edgerton
Keyword(s):  
Succinate Dehydrogenase ◽  
Muscle Fiber ◽  
Muscle Fibers ◽  
Cell Types ◽  
Mitochondrial Proteins ◽  
Succinate Dehydrogenase Activity ◽  
Fiber Size ◽  
The Right ◽  
Gastrocnemius Muscles ◽  
Selective Increase

To determine the level of coordination in succinate dehydrogenase (SDH) activity between plantaris motoneurons and muscle fibers, the soleus and gastrocnemius muscles were bilaterally excised in four cats to subject the plantaris to functional overload (FO). Five normal cats served as controls. Twelve weeks after surgery the right plantaris in each cat was injected with horseradish peroxidase to identify plantaris motoneurons. SDH activity then was measured in a population of plantaris motoneurons and muscle fibers in each cat. Control motoneurons and muscle fibers had similar mean SDH activities and a similar relationship between cell size and SDH activity. After FO, muscle fiber size doubled and mean muscle fiber SDH activity halved. Motoneuron mean SDH activity and size were unaffected by FO. Total SDH activity was unchanged in both the motoneurons and muscle fibers after FO. These changes suggest a selective increase in contractile proteins with little or no modulation of mitochondrial proteins in the muscle fibers, because total SDH activity was unchanged in muscle fibers after FO. These data demonstrate that although mean SDH activities were similar in control motoneurons and muscle fibers, mean SDH activities in these two cell types can change independently.

Variation and limitations in fiber enzymatic and size responses in hypertrophied muscle

1992 ◽  
Vol 73 (2) ◽  
pp. 631-641 ◽  
Author(s):  
G. R. Chalmers ◽  
R. R. Roy ◽  
V. R. Edgerton
Keyword(s):  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Muscle Fiber ◽  
Unit Volume ◽  
Muscle Fibers ◽  
Plantaris Muscle ◽  
Fiber Volume ◽  
Succinate Dehydrogenase Activity ◽  
Slow Myosin ◽  
Glycerophosphate Dehydrogenase

The present study was designed to determine whether the degree and kind of adaptation of a muscle fiber to a functional overload (FO) are determined by properties that are intrinsic to that fiber. The study also addresses the question of the capability of fibers to maintain a normal level of coordination of proteins per fiber as fiber volume changes dramatically. The plantaris muscle of six adult female cats was overloaded for 12 wk by bilateral synergist removal. Plantaris muscle fiber mean size doubled after FO, although some very small fibers that stained dark for adenosinetriphosphatase (ATPase) were observed in some of the FO muscles. There appeared to be no change in total succinate dehydrogenase activity per fiber. A reduction in succinate dehydrogenase activity per unit volume was observed in a substantial number of fibers, reflecting a disproportionate increase in fiber volume relative to mitochondrial volume. In contrast, total alpha-glycerophosphate dehydrogenase activity and actomyosin ATPase activity increased as fiber size increased, whereas there was no change in alpha-glycerophosphate dehydrogenase and ATPase activities per unit volume. Control and FO muscle fibers generally expressed either a fast or slow myosin heavy chain type, but in some cases FO muscle fibers expressed both fast and slow myosin heavy chains. The persistence of variability in fiber sizes and enzyme activities in fibers of overloaded muscles suggests a wide range in the adaptive potential of individual fibers to FO. These data indicate that a severalfold increase in cell size may occur without significant qualitative changes in the coordination of protein regulation associated with metabolic pathways and ATP utilization.

A semi-automated measurement of muscle fiber size using the Imaris software

2021 ◽  
Author(s):  
Jennifer E. Gilda ◽  
Joon-Hyuk Ko ◽  
Aviv-Yvonne Elfassy ◽  
Nadav Tropp ◽  
Anna Parnis ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Muscle Fiber ◽  
Cross Sections ◽  
Statistical Tests ◽  
Muscle Fibers ◽  
Fluorescent Labeling ◽  
Cross Sectional ◽  
Short Period ◽  
Fiber Size ◽  
Specific Protease

The size and shape of skeletal muscle fibers are affected by various physiological and pathological conditions, such as muscle atrophy, hypertrophy, regeneration, and dystrophies. Hence, muscle fiber cross-sectional area (CSA) is an important determinant of muscle health and plasticity. We adapted the Imaris software to automatically segment muscle fibers based on fluorescent labeling of the plasma membrane, and measure muscle fiber CSA. Analysis of muscle cross sections by the Imaris semi-automated and manual approaches demonstrated a similar decrease in CSA of atrophying muscles from fasted mice compared with fed controls. In addition, we previously demonstrated that downregulation of the Ca2+-specific protease calpain-1 attenuates muscle atrophy. Accordingly, both the Imaris semi-automated and manual approaches showed a similar increase in CSA of fibers expressing calpain-1 shRNA compared with adjacent non-transfected fibers in the same muscle cross section. Although both approaches seem valid for measurements of muscle fiber size, the manual marking method is less preferable because it is highly time-consuming, subjective, and limits the number of cells that can be analyzed. The Imaris semi-automated approach is user-friendly, requires little training or optimization, and can be used to efficiently and accurately mark thousands of fibers in a short period of time. As a novel addition to the commonly used statistics, we also describe statistical tests that quantify the strength of an effect on fiber size, enabling detection of significant differences between skewed distributions that would otherwise not be detected using typical methods.

Intracellular distribution of succinate dehydrogenase activity in skeletal muscle fibers of geese

1984 ◽  
Vol 62 (2) ◽  
pp. 235-240 ◽  
Author(s):  
H. J. Swatland
Keyword(s):  
Skeletal Muscle ◽  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Adenosine Triphosphatase ◽  
Muscle Fibers ◽  
Fiber Types ◽  
Succinate Dehydrogenase Activity ◽  
Individual Muscle ◽  
Concentric Zone ◽  
Pectoralis Muscles

Samples of iliotibialis anterior and pectoralis muscles were taken from five ganders (Anser domesticus). Serial transverse sections were reacted for succinate dehydrogenase (SDH) and alkali-stable adenosine triphosphatase (ATPase). The distribution of SDH activity within individual muscle fibers was measured with a scanning photometer. In many individual fibers, SDH activity was stronger in the periphery than in the axis. This gradient was steepest (−0.034 ± 0.019 absorbance units per concentric zone of 2 μm diameter measurements) in pectoralis fibers with strong SDH activity. In the pectoralis, radial gradients were correlated with fiber area so that the smallest fibers tended to have the steepest gradients of SDH activity. However, this relationship was reversed in fibers with strong ATPase and weak SDH activity in the iliotibialis anterior, and the largest fibers tended to have the steepest gradients. In all fiber types of both muscles, fibers with greater mean SDH activity tended to have steeper gradients.

Free autografting of entire limb muscles in the cat: histochemistry and biochemistry

1978 ◽  
Vol 44 (3) ◽  
pp. 431-437 ◽  
Author(s):  
L. C. Maxwell ◽  
J. A. Faulkner ◽  
S. A. Mufti ◽  
A. M. Turowski
Keyword(s):  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Muscle Fibers ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Succinate Dehydrogenase Activity ◽  
Cross Sectional ◽  
The Mean ◽  
Fast Twitch

Fifty extensor digitorium longus muscles of 25 cats were autografted, 33 with and 17 without prior denervation. After 50 days, no significant differences were observed between predenervated and nonpredenervated autografts. Autografted muscles weighed 48% of the weight of control muscles. Few original muscle fibers survived and within 2 wk autografts contained regenerating muscle fibers. The mean cross-sectional area of muscle fibers in the autografts reached 125% of the value for control nontransplanted muscles. The mean percentage of fibers classified high oxidative in autografted muscles was 67% of values for control muscles. SDH activity of autografted muscle homogenates reached 55% of control values. Up to 60 days after surgery autografts had only fast-twitch fibers. At 170 days autografts remained 95% fast twitch in composition. Revascularization began within 4 days, but the capillary to fiber ratio of long term autografts reached only 60% of control values. Although fiber hypertrophy suggests that cats use autografted muscles, lower than control succinate dehydrogenase activity may result from altered recruitment.

scholarly journals Genomic predictors of testosterone levels are associated with muscle fiber size and strength

2021 ◽  
Author(s):  
João Paulo L. F. Guilherme ◽  
Ekaterina A. Semenova ◽  
Oleg V. Borisov ◽  
Andrey K. Larin ◽  
Ethan Moreland ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Handgrip Strength ◽  
Muscle Fibers ◽  
Fat Free Mass ◽  
Nucleotide Polymorphisms ◽  
Cross Sectional ◽  
Testosterone Levels ◽  
Fiber Size ◽  
Fast Twitch Muscle ◽  
Fast Twitch

Abstract Purpose Circulating testosterone levels are a heritable trait with anabolic properties in various tissues, including skeletal muscle. So far, hundreds of single nucleotide polymorphisms (SNPs) associated with testosterone levels have been identified in nonathletic populations. The aim of the present study was to test the association of 822 testosterone-increasing SNPs with muscle-related traits (muscle fiber size, fat-free mass and handgrip strength) and to validate the identified SNPs in independent cohorts of strength and power athletes. Methods One hundred and forty-eight physically active individuals (47 females, 101 males) were assessed for cross-sectional area (CSA) of fast-twitch muscle fibers. Significant SNPs were further assessed for fat-free mass and handgrip strength in > 354,000 participants from the UK Biobank cohort. The validation cohorts included Russian elite athletes. Results From an initial panel of 822 SNPs, we identified five testosterone-increasing alleles (DOCK3 rs77031559 G, ESR1 rs190930099 G, GLIS3 rs34706136 TG, GRAMD1B rs850294 T, TRAIP rs62260729 C) nominally associated (P < 0.05) with CSA of fast-twitch muscle fibers, fat-free mass and handgrip strength. Based on these five SNPs, the number of testosterone-increasing alleles was positively associated with testosterone levels in male athletes (P = 0.048) and greater strength performance in weightlifters (P = 0.017). Moreover, the proportion of participants with ≥ 2 testosterone-increasing alleles was higher in power athletes compared to controls (68.9 vs. 55.6%; P = 0.012). Conclusion Testosterone-related SNPs are associated with muscle fiber size, fat-free mass and strength, which combined can partially contribute to a greater predisposition to strength/power sports.

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