Lower activity of oxidative key enzymes and smaller fiber areas in skeletal muscle of postobese women

1998 ◽  
Vol 275 (3) ◽  
pp. E487-E494 ◽  
Author(s):  
Anne Raben ◽  
Elsebeth Mygind ◽  
Arne Astrup
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Normal Weight ◽  
Fiber Types ◽  
Fiber Morphology ◽  
Key Enzymes ◽  
Control Subjects ◽  
Type Composition ◽  
And Control

Muscle fiber morphology and activities of four key enzymes, as well as energy metabolism, were determined in nine normal-weight postobese women and nine matched control subjects. No differences in fiber type composition, but a smaller mean fiber area and area of fiber types I and IIb, were found in postobese compared with control subjects ( P < 0.05). The activities of β-hydroxyacyl-CoA dehydrogenase (HADH) and citrate synthase (CS) were 20% lower in postobese than in control subjects ( P < 0.05). However, the activities of lactate dehydrogenase and lipoprotein lipase were not significantly different between postobese and control subjects. Basal metabolic rate and respiratory exchange ratio were also similar, but maximal oxygen uptake (V˙o 2 max) tended to be lower in postobese than in control subjects ( P = 0.06). When adjustments were made for differences inV˙o 2 max, HADH and CS were not different between postobese and control subjects. In conclusion, these data suggest that smaller fiber areas and lower enzyme activities, i.e., markers of aerobic capacity of skeletal muscle, but not fiber composition, may be factors predisposing to obesity.

Gene Polymorphisms and Fiber-Type Composition of Human Skeletal Muscle

2012 ◽  
Vol 22 (4) ◽  
pp. 292-303 ◽  
Author(s):  
Ildus I. Ahmetov ◽  
Olga L. Vinogradova ◽  
Alun G. Williams
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Fiber Type Composition ◽  
Type Composition ◽  
Type I Fibers

The ability to perform aerobic or anaerobic exercise varies widely among individuals, partially depending on their muscle-fiber composition. Variability in the proportion of skeletal-muscle fiber types may also explain marked differences in aspects of certain chronic disease states including obesity, insulin resistance, and hypertension. In untrained individuals, the proportion of slow-twitch (Type I) fibers in the vastus lateralis muscle is typically around 50% (range 5–90%), and it is unusual for them to undergo conversion to fast-twitch fibers. It has been suggested that the genetic component for the observed variability in the proportion of Type I fibers in human muscles is on the order of 40–50%, indicating that muscle fiber-type composition is determined by both genotype and environment. This article briefly reviews current progress in the understanding of genetic determinism of fiber-type proportion in human skeletal muscle. Several polymorphisms of genes involved in the calcineurin–NFAT pathway, mitochondrial biogenesis, glucose and lipid metabolism, cytoskeletal function, hypoxia and angiogenesis, and circulatory homeostasis have been associated with fiber-type composition. As muscle is a major contributor to metabolism and physical strength and can readily adapt, it is not surprising that many of these gene variants have been associated with physical performance and athlete status, as well as metabolic and cardiovascular diseases. Genetic variants associated with fiber-type proportions have important implications for our understanding of muscle function in both health and disease.

scholarly journals Calcineurin Is Necessary for the Maintenance but Not Embryonic Development of Slow Muscle Fibers

2005 ◽  
Vol 25 (15) ◽  
pp. 6629-6638 ◽  
Author(s):  
Misook Oh ◽  
Igor I. Rybkin ◽  
Victoria Copeland ◽  
Michael P. Czubryt ◽  
John M. Shelton ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Specific Expression ◽  
Interacting Protein ◽  
Type Composition ◽  
Slow Fiber ◽  
Fast Twitch

ABSTRACT Skeletal muscles are a mosaic of slow and fast twitch myofibers. During embryogenesis, patterns of fiber type composition are initiated that change postnatally to meet physiological demand. To examine the role of the protein phosphatase calcineurin in the initiation and maintenance of muscle fiber types, we used a “Flox-ON” approach to obtain muscle-specific overexpression of the modulatory calcineurin-interacting protein 1 (MCIP1/DSCR1), an inhibitor of calcineurin. Myo-Cre transgenic mice with early skeletal muscle-specific expression of Cre recombinase were used to activate the Flox-MCIP1 transgene. Contractile components unique to type 1 slow fibers were absent from skeletal muscle of adult Myo-Cre/Flox-MCIP1 mice, whereas oxidative capacity, myoglobin content, and mitochondrial abundance were unaltered. The soleus muscles of Myo-Cre/Flox-MCIP1 mice fatigued more rapidly than the wild type as a consequence of the replacement of the slow myosin heavy chain MyHC-1 with a fast isoform, MyHC-2A. MyHC-1 expression in Myo-Cre/Flox-MCIP1 embryos and early neonates was normal. These results demonstrate that developmental patterning of slow fibers is independent of calcineurin, while the maintenance of the slow-fiber phenotype in the adult requires calcineurin activity.

Skeletal muscle structural and energetic characteristics in subjects with sickle cell trait, α-thalassemia, or dual hemoglobinopathy

2010 ◽  
Vol 109 (3) ◽  
pp. 728-734 ◽  
Author(s):  
Lucile Vincent ◽  
Léonard Féasson ◽  
Samuel Oyono-Enguéllé ◽  
Viviane Banimbek ◽  
Géraldine Monchanin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sickle Cell ◽  
Power Output ◽  
Citrate Synthase ◽  
Sickle Cell Trait ◽  
Fiber Type ◽  
Time To Exhaustion ◽  
Fiber Types ◽  
Maximal Power ◽  
Maximal Power Output

Previous studies have shown that subjects with sickle cell trait (SCT), α-thalassemia (α-t), and the dual hemoglobinopathy (SCT/α-t) manifest subtle, albeit significant, differences during exercise. To better understand such differences, we assessed skeletal muscle histomorphological and energetic characteristics in 10 control HbAA subjects (C), 5 subjects with α-t (α-t), 6 SCT carriers (SCT) and 9 SCT carriers with α-t (SCT/α-t). Subjects underwent a muscle biopsy and also performed an incremental maximal exercise and a time to exhaustion test. There were no observable differences in daily energy expenditure, maximal power output (Pmax), or time to exhaustion at 110% Pmax ( Tex) among the groups. Blood lactate concentrations measured at the end of the Tex, muscle fiber type distribution, and mean phosphofructokinase (PFK), lactate dehydrogenase (LDH), β-hydroxyacyl-CoA-dehydrogenase (HAD), and citrate synthase (CS) activities were all similar among the four groups. However, SCT was associated with a lower cytochrome- c oxidase (COx) activity in type IIa fibers ( P < 0.05), and similar trends were observed in fiber types I and IIx. Trends toward lower creatine kinase (CK) activity ( P = 0.0702) and higher surface area of type IIx fibers were observed in SCT ( P = 0.0925). In summary, these findings support most of the previous observations in SCT, such as 1) similar maximal power output and associated maximal oxygen consumption (V̇o2max) values and 2) lower exercise performances during prolonged submaximal exercise. Furthermore, performances during short supramaximal exercise were not different in SCT. Finally, the dual hemoglobinopathy condition does not seem to affect muscle characteristics.

Strength, power, fiber types, and mRNA expression in trained men and women with different ACTN3 R577X genotypes

2009 ◽  
Vol 106 (3) ◽  
pp. 959-965 ◽  
Author(s):  
Barbara Norman ◽  
Mona Esbjörnsson ◽  
Håkan Rundqvist ◽  
Ted Österlund ◽  
Ferdinand von Walden ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Muscle Fiber Types ◽  
Vastus Lateralis Muscle ◽  
Fiber Types ◽  
Mrna Levels ◽  
Men And Women ◽  
Fiber Type Composition ◽  
Type Composition

α-Actinins are structural proteins of the Z-line. Human skeletal muscle expresses two α-actinin isoforms, α-actinin-2 and α-actinin-3, encoded by their respective genes ACTN2 and ACTN3. ACTN2 is expressed in all muscle fiber types, while only type II fibers, and particularly the type IIb fibers, express ACTN3. ACTN3 (R577X) polymorphism results in loss of α-actinin-3 and has been suggested to influence skeletal muscle function. The X allele is less common in elite sprint and power athletes than in the general population and has been suggested to be detrimental for performance requiring high power. The present study investigated the association of ACTN3 genotype with muscle power during 30-s Wingate cycling in 120 moderately to well-trained men and women and with knee extensor strength and fatigability in a subset of 21 men performing isokinetic exercise. Muscle biopsies were obtained from the vastus lateralis muscle to determine fiber-type composition and ACTN2 and ACTN3 mRNA levels. Peak and mean power and the torque-velocity relationship and fatigability output showed no difference across ACTN3 genotypes. Thus this study suggests that R577X polymorphism in ACTN3 is not associated with differences in power output, fatigability, or force-velocity characteristics in moderately trained individuals. However, repeated exercise bouts prompted an increase in peak torque in RR but not in XX genotypes, suggesting that ACTN3 genotype may modulate responsiveness to training. Our data further suggest that α-actinins do not play a significant role in determining muscle fiber-type composition. Finally, we show that ACTN2 expression is affected by the content of α-actinin-3, which implies that α-actinin-2 may compensate for the lack of α-actinin-3 and hence counteract the phenotypic consequences of the deficiency.

scholarly journals Skeletal muscle of females and males with constitutional thinness: a low intramuscular lipid content and oxidative profile

2020 ◽  
Vol 45 (11) ◽  
pp. 1287-1298 ◽  
Author(s):  
Mélina Bailly ◽  
Natacha Germain ◽  
Léonard Féasson ◽  
Frédéric Costes ◽  
Bruno Estour ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Weight Control ◽  
Glycogen Content ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Oxidative Capacity ◽  
Normal Weight ◽  
Type I ◽  
Before And After

Constitutional thinness (CT) is a nonpathological state of underweight. The current study aimed to explore skeletal muscle energy storage in individuals with CT and to further characterize muscle phenotype at baseline and in response to overfeeding. Thirty subjects with CT (15 females, 15 males) and 31 normal-weight control subjects (16 females, 15 males) participated in the study. Histological and enzymological analyses were performed on muscle biopsy specimens before and after overfeeding. In the skeletal muscle of CT participants compared with controls, we observed a lower content of intramuscular triglycerides for type I (−17%, p < 0.01) and type IIA (−14%, p < 0.05) muscle fibers, a lower glycogen content for type I (−6%, p < 0.01) and type IIA (−5%, p < 0.05) muscle fibers, a specific fiber-type distribution, a marked muscle hypotrophy (−20%, p < 0.001), a low capillary-to-fiber ratio (−19%, p < 0.001), and low citrate synthase activity (−18%, p < 0.05). In response to overfeeding, CT participants increased their intramuscular triglycerides content in type I (+10%, p < 0.01) and type IIA (+9%, p < 0.01) muscle fibers. CT individuals seem to present an unusual muscle phenotype and different adaptations to overfeeding compared with normal-weight individuals, suggesting a specific energy metabolism and muscle adaptations. ClinicalTrials.gov registration no. NCT02004821. Novelty Low intramuscular triglycerides and glycogen content in skeletal muscle of constitutionally thin individuals. Low oxidative capacity, low capillary supply, and fiber hypotrophy in skeletal muscle of constitutionally thin individuals. Increase in intramuscular triglycerides in constitutional thinness in response to overfeeding.

The KATP channel Kir6.2 subunit content is higher in glycolytic than oxidative skeletal muscle fibers

2011 ◽  
Vol 301 (4) ◽  
pp. R916-R925 ◽  
Author(s):  
Krystyna Banas ◽  
Charlene Clow ◽  
Bernard J. Jasmin ◽  
Jean-Marc Renaud
Keyword(s):  
Skeletal Muscle ◽  
Cross Sections ◽  
Fiber Type ◽  
Energy Levels ◽  
Muscle Fibers ◽  
Metabolic Stress ◽  
Oxidative Capacity ◽  
Fiber Types ◽  
Fiber Damage ◽  
The Individual

It has long been suggested that in skeletal muscle, the ATP-sensitive K+ channel (KATP) channel is important in protecting energy levels and that abolishing its activity causes fiber damage and severely impairs function. The responses to a lack of KATP channel activity vary between muscles and fibers, with the severity of the impairment being the highest in the most glycolytic muscle fibers. Furthermore, glycolytic muscle fibers are also expected to face metabolic stress more often than oxidative ones. The objective of this study was to determine whether the t-tubular KATP channel content differs between muscles and fiber types. KATP channel content was estimated using a semiquantitative immunofluorescence approach by staining cross sections from soleus, extensor digitorum longus (EDL), and flexor digitorum brevis (FDB) muscles with anti-Kir6.2 antibody. Fiber types were determined using serial cross sections stained with specific antimyosin I, IIA, IIB, and IIX antibodies. Changes in Kir6.2 content were compared with changes in CaV1.1 content, as this Ca2+ channel is responsible for triggering Ca2+ release from sarcoplasmic reticulum. The Kir6.2 content was the lowest in the oxidative soleus and the highest in the glycolytic EDL and FDB. At the individual fiber level, the Kir6.2 content within a muscle was in the order of type IIB > IIX > IIA ≥ I. Interestingly, the Kir6.2 content for a given fiber type was significantly different between soleus, EDL, and FDB, and highest in FDB. Correlations of relative fluorescence intensities from the Kir6.2 and CaV1.1 antibodies were significant for all three muscles. However, the variability in content between the three muscles or individual fibers was much greater for Kir6.2 than for CaV1.1. It is suggested that the t-tubular KATP channel content increases as the glycolytic capacity increases and as the oxidative capacity decreases and that the expression of KATP channels may be linked to how often muscles/fibers face metabolic stress.

Endotoxin administration alters the force vs. pCa relationship of skeletal muscle fibers

2000 ◽  
Vol 278 (4) ◽  
pp. R891-R896 ◽  
Author(s):  
G. Supinski ◽  
D. Nethery ◽  
T. M. Nosek ◽  
L. A. Callahan ◽  
D. Stofan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Force ◽  
Fiber Type ◽  
Contractile Proteins ◽  
Hill Coefficient ◽  
Control Group ◽  
Fiber Types ◽  
Endotoxin Administration ◽  
Generating Capacity ◽  
The Hill

Recent work indicates that endotoxemia elicits severe reductions in skeletal muscle force-generating capacity. The subcellular alterations responsible for these decrements have not, however, been fully characterized. One possibility is that the contractile proteins per se are altered in endotoxemia and another is that the mechanism by which these proteins are activated is affected. The purpose of the present study was to assess the effects of endotoxin administration on the contractile proteins by examining the maximum calcium-activated force (Fmax) and calcium sensitivity of single Triton-skinned fibers of diaphragm, soleus, and extensor digitorum longus (EDL) muscles taken from control and endotoxin-treated (8 mg/kg) rats. Fibers were mounted on a force transducer and sequentially activated by serial immersion in solutions of increasing Ca2+ concentration (i.e., pCa 6.0 to pCa 5.0); force vs. pCa data were fit to the Hill equation. All fibers were typed at the conclusion of studies using gel electrophoresis. Fmax, the calcium concentration required for half-maximal activation (Ca50), and the Hill coefficient were compared as a function of muscle and fiber type for the control and endotoxin-treated animals. Control group Fmax was similar for diaphragm, soleus, and EDL fibers, i.e., 112.34 ± 2.64, 111.55 ± 3.66, and 104.05 ± 4.33 kPa, respectively. Endotoxin administration reduced the average Fmax for fibers from all three muscles to 80.25 ± 2.30, 72.47 ± 2.97, and 78.32 ± 2.43 kPa, respectively ( P < 0.001 for comparison of each to control). All fiber types in diaphragm, soleus, and EDL muscles manifested similar endotoxin-related reductions in Fmax. The Ca50 and the Hill coefficient for all fiber types and all muscles were unaffected by endotoxin administration. We speculate that these alterations in the intrinsic properties of the contractile proteins represent a major mechanism by which endotoxemia reduces muscle force-generating capacity.

Blood flow to different skeletal muscle fiber types during contraction

1983 ◽  
Vol 245 (2) ◽  
pp. H265-H275 ◽  
Author(s):  
B. G. Mackie ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Skeletal Muscle Fiber ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Blood Flows ◽  
Fast Twitch

Blood flow to fast-twitch red (FTR), fast-twitch white (FTW), and slow-twitch red (STR) muscle fiber sections of the gastrocnemius-plantaris-soleus muscle group was determined using 15 +/- 3-microns microspheres during in situ stimulation in pentobarbital-anesthetized rats. Steady-state blood flows were assessed during the 10th min of contraction using twitch (0.1, 0.5, 1, 3, and 5 Hz) and tetanic (7.5, 15, 30, 60, and 120/min) stimulation conditions. In addition, an earlier blood flow determination was begun at 3 min (twitch series) or at 30 s (tetanic series) of stimulation. Blood flow was highest in the FTR (220-240 ml X min-1 X 100 g-1), intermediate in the STR (140), and lowest in the FTW (70-80) section during tetanic contraction conditions estimated to coincide with the peak aerobic function of each fiber type. These blood flows are fairly proportional to the differences in oxidative capacity among fiber types. Further, their absolute values are similar to those predicted from the relationship between blood flow and oxidative capacity found by others for dog and cat muscles. During low-frequency contraction conditions, initial blood flow to the FTR and STR sections were excessively high and not dependent on contraction frequency. However, blood flows subsequently decreased to values in keeping with the relative energy demands. In contrast, FTW muscle did not exhibit this time-dependent relative hyperemia. Thus, besides the obvious quantitative differences between skeletal muscle fiber types, there are qualitative differences in blood flow response during contractions. Our findings establish that, based on fiber type composition, a heterogeneity in blood flow distribution can occur within a whole muscle during contraction.

Influence of training on skeletal muscle enzymatic adaptations in normal and diabetic rats

1985 ◽  
Vol 249 (4) ◽  
pp. E360-E365 ◽  
Author(s):  
E. G. Noble ◽  
C. D. Ianuzzo
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
Citrate Synthase ◽  
Diabetic Rats ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Marker Enzymes ◽  
Oxidative Potential ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Fast Twitch

Muscle homogenates representing slow-twitch oxidative, fast-twitch oxidative-glycolytic, fast-twitch glycolytic, and mixed fiber types were prepared from normal, diabetic, and insulin-treated diabetic rats. Diabetes was induced by injection of 80 mg . kg-1 of streptozotocin. The activities of citrate synthase, succinate dehydrogenase, and 3-hydroxyacyl-CoA dehydrogenase were employed as markers of oxidative potential, whereas phosphorylase, hexokinase, and phosphofructokinase activities were used as an indication of glycolytic capacity. Diabetes was associated with a general decrement in the activity of oxidative marker enzymes for all fiber types except the fast-twitch glycolytic fiber. In contrast, the fast-twitch glycolytic fibers demonstrated the greatest decline in glycolytic enzymatic activity. Insulin-treated animals, either trained or untrained, exhibited enzyme activities similar to their normal counterparts. Exercise training of diabetic rats mimicked the effect of insulin treatment and caused a near normalization of the activity of the marker enzymes. These findings suggest that the enzymatic potential of all skeletal muscle fiber types of diabetic rats may be normalized by exercise training even in the absence of significant amounts of insulin.

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