Interrelationships between muscle morphology, insulin action, and adiposity

1996 ◽  
Vol 270 (6) ◽  
pp. R1332-R1339 ◽  
Author(s):  
A. D. Kriketos ◽  
D. A. Pan ◽  
S. Lillioja ◽  
G. J. Cooney ◽  
L. A. Baur ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Body Fat ◽  
Muscle Fiber ◽  
Insulin Action ◽  
Fiber Type ◽  
Oxidative Capacity ◽  
Muscle Fiber Type ◽  
Type I ◽  
Fa Composition ◽  
Type I Fibers

There is evidence that insulin resistance and obesity are associated with relative increases in the proportion of glycolytic type IIb muscle fibers and decreases in the proportion of oxidative type I fibers. Futhermore, insulin resistance and obesity are associated with the fatty acid (FA) profile of structural membrane lipids. The present study was undertaken to define interrelationships between muscle fiber type and oxidative capacity, muscle membrane FA composition, and insulin action and obesity. Muscle morphology, insulin action, and body fat content were measured in 48 male nondiabetic Pima Indians. Percent body fat (pFAT, determined by hydrodensitometry) correlated negatively with percentage of type I fibers (r = -0.44, P = 0.002) and positively with percentage of type IIb fibers (r = 0.40, P = 0.005). Consistent with this finding, pFAT was also significantly related to oxidative capacity of muscle, as assessed by NADH staining (r = -0.47, P = 0.0007) and citrate synthase (CS) activity (r = -0.43, P = 0.008). Insulin action was correlated with oxidative capacity (CS; r = 0.41, P = 0.01) and weakly correlated with percentage of type IIb fibers (r = -0.29, P = 0.05). In addition, relationships were shown between muscle fiber type and FA composition (e.g., percentage of type I fibers related to n-3 FA; r = 0.37, P = 0.01). Thus leaness and insulin sensitivity are associated with increased oxidative capacity and unsaturation of membranes in skeletal muscle. Present studies support the hypothesis that muscle oxidative capacity and fiber type may play a genetically determined or an environmentally modified role in development of obesity and insulin resistance.

Muscle fiber type is associated with obesity and weight loss

2002 ◽  
Vol 282 (6) ◽  
pp. E1191-E1196 ◽  
Author(s):  
Charles J. Tanner ◽  
Hisham A. Barakat ◽  
G. Lynis Dohm ◽  
Walter J. Pories ◽  
Kenneth G. MacDonald ◽  
...  
Keyword(s):  
Weight Loss ◽  
Muscle Fiber ◽  
Excess Weight Loss ◽  
Fiber Type ◽  
Gastric Bypass Surgery ◽  
Muscle Fiber Type ◽  
Morbidly Obese ◽  
Type I ◽  
Obese Women ◽  
Type I Fibers

The purpose of this study was to test the hypothesis that muscle fiber type is related to obesity. Fiber type was compared 1) in lean and obese women, 2) in Caucasian (C) and African-American (AA) women, and 3) in obese individuals who lost weight after gastric bypass surgery. When lean (body mass index 24.0 ± 0.9 kg/m2, n = 28) and obese (34.8 ± 0.9 kg/m2, n = 25) women were compared, there were significant ( P < 0.05) differences in muscle fiber type. The obese women possessed fewer type I (41.5 ± 1.8 vs. 54.6 ± 1.8%) and more type IIb (25.1 ± 1.5 vs. 14.4 ± 1.5%) fibers than the lean women. When ethnicity was accounted for, the percentage of type IIb fibers in obese AA was significantly higher than in obese C (31.0 ± 2.4% vs. 19.2 ± 1.9%); fewer type I fibers were also found in obese AA (34.5 ± 2.8% vs. 48.6 ± 2.2%). These data are consistent with the higher incidence of obesity and greater weight gain reported in AA women. With weight loss intervention, there was a positive relationship ( r = 0.72, P < 0.005) between the percentage of excess weight loss and the percentage of type I fibers in morbidly obese patients. These findings indicate that there is a relationship between muscle fiber type and 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.

Carnitine metabolism in human muscle fiber types during submaximal dynamic exercise

1996 ◽  
Vol 80 (3) ◽  
pp. 1061-1064 ◽  
Author(s):  
D. Constantin-Teodosiu ◽  
S. Howell ◽  
P. L. Greenhaff
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Group Formation ◽  
Free Carnitine ◽  
Muscle Fiber Types ◽  
Type I ◽  
Fiber Types ◽  
Carnitine Metabolism ◽  
Type I Fibers

The effect of prolonged exhaustive exercise on free carnitine and acetylcarnitine concentrations in mixed-fiber skeletal muscle and in type I and II muscle fibers was investigated in humans. Needle biopsy samples were obtained from the vastus lateralis of six subjects immediately after exhaustive one-legged cycling at approximately 75% of maximal O2 uptake from both the exercised and nonexercised (control) legs. In the resting (control) leg, there was no difference in the free carnitine concentration between type I and II fibers (20.36 +/- 1.25 and 20.51 +/- 1.16 mmol/kg dry muscle, respectively) despite the greater potential for fat oxidation in type I fibers. However, the acetylcarnitine concentration was slightly greater in type I fibers (P < 0.01). During exercise, acetylcarnitine accumulation occurred in both muscle fiber types, but accumulation was greatest in type I fibers (P < 0.005). Correspondingly, the concentration of free carnitine was significantly lower in type I fibers at the end of exercise (P < 0.001). The sum of free carnitine and acetylcarnitine concentrations in type I and II fibers at rest was similar and was unchanged by exercise. In conclusion, the findings of the present study support the suggestion that carnitine buffers excess acetyl group formation during exercise and that this occurs in both type I and II fibers. However, the greater accumulation of acetylcarnitine in type I fibers during prolonged exercise probably reflects the greater mitochondrial content of this fiber type.

scholarly journals Overexpression of TRB3 in muscle alters muscle fiber type and improves exercise capacity in mice

2014 ◽  
Vol 306 (12) ◽  
pp. R925-R933 ◽  
Author(s):  
Ding An ◽  
Sarah J. Lessard ◽  
Taro Toyoda ◽  
Min-Young Lee ◽  
Ho-Jin Koh ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Capacity ◽  
Muscle Fiber ◽  
Wheel Running ◽  
Fiber Type ◽  
Muscle Fiber Type ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Type I ◽  
Pronounced Increase

Increasing evidence suggests that TRB3, a mammalian homolog of Drosophila tribbles, plays an important role in cell growth, differentiation, and metabolism. In the liver, TRB3 binds and inhibits Akt activity, whereas in adipocytes, TRB3 upregulates fatty acid oxidation. In cultured muscle cells, TRB3 has been identified as a potential regulator of insulin signaling. However, little is known about the function and regulation of TRB3 in skeletal muscle in vivo. In the current study, we found that 4 wk of voluntary wheel running (6.6 ± 0.4 km/day) increased TRB3 mRNA by 1.6-fold and protein by 2.5-fold in the triceps muscle. Consistent with this finding, muscle-specific transgenic mice that overexpress TRB3 (TG) had a pronounced increase in exercise capacity compared with wild-type (WT) littermates (TG: 1,535 ± 283; WT: 644 ± 67 joules). The increase in exercise capacity in TRB3 TG mice was not associated with changes in glucose uptake or glycogen levels; however, these mice displayed a dramatic shift toward a more oxidative/fatigue-resistant (type I/IIA) muscle fiber type, including threefold more type I fibers in soleus muscles. Skeletal muscle from TRB3 TG mice had significantly decreased PPARα expression, twofold higher levels of miR208b and miR499, and corresponding increases in the myosin heavy chain isoforms Myh7 and Myb7b, which encode these microRNAs. These findings suggest that TRB3 regulates muscle fiber type via a peroxisome proliferator-activated receptor-α (PPAR-α)-regulated miR499/miR208b pathway, revealing a novel function for TRB3 in the regulation of skeletal muscle fiber type and exercise capacity.

scholarly journals The influence of training status, age, and muscle fiber type on cycling efficiency and endurance performance

2013 ◽  
Vol 115 (5) ◽  
pp. 723-729 ◽  
Author(s):  
James G. Hopker ◽  
Damian A. Coleman ◽  
Hannah C. Gregson ◽  
Simon A. Jobson ◽  
Tobias Von der Haar ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Power Output ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Cycling Performance ◽  
Muscle Fiber Type ◽  
Type I ◽  
Maximal Heart Rate ◽  
Training Status ◽  
Cycling Efficiency

The purpose of this study was to assess the influence of age, training status, and muscle fiber-type distribution on cycling efficiency. Forty men were recruited into one of four groups: young and old trained cyclists, and young and old untrained individuals. All participants completed an incremental ramp test to measure their peak O2 uptake, maximal heart rate, and maximal minute power output; a submaximal test of cycling gross efficiency (GE) at a series of absolute and relative work rates; and, in trained participants only, a 1-h cycling time trial. Finally, all participants underwent a muscle biopsy of their right vastus lateralis muscle. At relative work rates, a general linear model found significant main effects of age and training status on GE ( P < 0.01). The percentage of type I muscle fibers was higher in the trained groups ( P < 0.01), with no difference between age groups. There was no relationship between fiber type and cycling efficiency at any work rate or cadence combination. Stepwise multiple regression indicated that muscle fiber type did not influence cycling performance ( P > 0.05). Power output in the 1-h performance trial was predicted by average O2 uptake and GE, with standardized β-coefficients of 0.94 and 0.34, respectively, although some mathematical coupling is evident. These data demonstrate that muscle fiber type does not affect cycling efficiency and was not influenced by the aging process. Cycling efficiency and the percentage of type I muscle fibers were influenced by training status, but only GE at 120 revolutions/min was seen to predict cycling performance.

Muscle Fiber Type Distribution in the Normal Human Levator Veli Palatini Muscle

1998 ◽  
Vol 35 (5) ◽  
pp. 419-424 ◽  
Author(s):  
Jerald B. Moon ◽  
Sue Ann Thompson ◽  
Elise Jaeckel ◽  
John W. Canady
Keyword(s):  
Muscle Tissue ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Type I ◽  
Type Ii ◽  
Type Distribution ◽  
Levator Veli Palatini ◽  
Fiber Type Distribution ◽  
Type I Fibers ◽  
Type Ii Fibers

Objective This study examined the muscle fiber type distribution within the normal adult levator veli palatini muscle. Methods Levator veli palatini muscle tissue was harvested from the palates of 12 (seven female, five male) adult noncleft cadavers. Adjacent sections were stained for adenosine triphosphatase at pH 10.4 or 4.2. After mounting, magnifying, and photographing, Type I versus Type II fiber types were differentiated by the intensity of, or by the inhibition of, staining of matched fibers at each pH level. Type I fibers stained light at pH 10.4 and dark at pH 4.2, while Type II fibers stained light at pH 4.2 and dark at pH 10.4. Main outcome Measures The number of fibers counted for each specimen ranged from 60 to 616. The numbers of Type I and Type II stained fibers appearing in each muscle tissue sample were determined and expressed as a percentage of the total number of fibers identified. A few identified fibers could not be labelled as either Type I or Type II. Results The overall proportion of Type I fibers, averaged across all specimens, was 59.8%. Male specimens had 67.4% Type I fibers and 31.8% Type II fibers, while female specimens had 54.4% Type I fibers and 44.4% Type II fibers. Conclusions Observed fiber type distributions were similar to those reported for other articulatory muscles, but differed slightly from previously reported distributions for normal levator veli palatini. The distributions observed in this study provide a baseline against which to relate fiber type data from the levator veli palatini of cleft palates to the functional status of the velopharyngeal mechanism.

Muscle fiber type specificity in insulin signal transduction

1999 ◽  
Vol 277 (6) ◽  
pp. R1690-R1696 ◽  
Author(s):  
Xiao Mei Song ◽  
Jeffrey W. Ryder ◽  
Yuichi Kawano ◽  
Alexander V. Chibalin ◽  
Anna Krook ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Tyrosine Phosphorylation ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Insulin Response ◽  
Muscle Fiber Type ◽  
Specific Response ◽  
Type I ◽  
Akt Kinase ◽  
Sustained Activity

We determined the muscle fiber type-specific response of intracellular signaling proteins to insulin. Epitrochlearis (Epi; 15% type I, 20% type IIa, and 65% type IIb), soleus (84, 16, and 0%), and extensor digitorum longus (EDL; 3, 57, and 40%) muscles from Wistar rats were incubated without or with 120 nM insulin (3–40 min). Peak insulin receptor (IR) tyrosine phosphorylation was reached after 6 (soleus) and 20 (Epi and EDL) min, with sustained activity throughout insulin exposure (40 min). Insulin increased insulin receptor substrate (IRS)-1 and IRS-2 tyrosine phosphorylation and phosphotyrosine-associated phosphatidylinositol (PI)-3-kinase activity to a maximal level after 3–10 min, with subsequent downregulation. Akt kinase phosphorylation peaked at 20 min, with sustained activity throughout insulin exposure. Importantly, the greatest insulin response for all signaling intermediates was observed in soleus, whereas the insulin response between EDL and Epi was similar. Protein expression of the p85α-subunit of PI 3-kinase and Akt kinase, but not IR, IRS-1, or IRS-2, was greater in oxidative versus glycolytic muscle. In conclusion, increased function and/or expression of key proteins in the insulin-signaling cascade contribute to fiber type-specific differences in insulin action in skeletal muscle.

Cold-induced PGC-1α expression modulates muscle glucose uptake through an insulin receptor/Akt-independent, AMPK-dependent pathway

2004 ◽  
Vol 287 (4) ◽  
pp. E686-E695 ◽  
Author(s):  
Rachel L. G. S. Oliveira ◽  
Mirian Ueno ◽  
Cláudio T. de Souza ◽  
Márcio Pereira-da-Silva ◽  
Alessandra L. Gasparetti ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Glucose Uptake ◽  
Tyrosine Phosphorylation ◽  
Muscle Fiber ◽  
Cold Exposure ◽  
Antisense Oligonucleotide ◽  
Fiber Type ◽  
Muscle Fiber Type ◽  
Membrane Localization ◽  
Type I

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) participates in control of expression of genes involved in adaptive thermogenesis, muscle fiber type differentiation, and fuel homeostasis. The objective of the present study was to evaluate the participation of cold-induced PGC-1α expression in muscle fiber type-specific activity of proteins that belong to the insulin-signaling pathway. Rats were exposed to 4°C for 4 days and acutely treated with insulin in the presence or absence of an antisense oligonucleotide to PGC-1α. Cold exposure promoted a significant increase of PGC-1α and uncoupling protein-3 protein expression in type I and type II fibers of gastrocnemius muscle. In addition, cold exposure led to higher glucose uptake during a hyperinsulinemic clamp, which was accompanied by higher expression and membrane localization of GLUT4 in both muscle fiber types. Cold exposure promoted significantly lower insulin-induced tyrosine phosphorylation of the insulin receptor (IR) and Ser473 phosphorylation of acute transforming retrovirus thymoma (Akt) and an insulin-independent increase of Thr172 phosphorylation of adenosine 5′-monophosphate-activated protein kinase (AMPK). Inhibition of PGC-1α expression in cold-exposed rats by antisense oligonucleotide treatment diminished glucose clearance rates during a hyperinsulinemic clamp and reduced expression and membrane localization of GLUT4. Reduction of PGC-1α expression resulted in no modification of insulin-induced tyrosine phosphorylation of the IR and Ser473 phosphorylation of Akt. Finally, reduction of PGC-1α resulted in lower Thr172 phosphorylation of AMPK. Thus cold-induced hyperexpression of PGC-1α participates in control of skeletal muscle glucose uptake through a mechanism that controls GLUT4 expression and subcellular localization independent of the IR and Akt activities but dependent on AMPK.

scholarly journals Fiber Composition and Oxidative Capacity of Hamster Skeletal Muscle

2002 ◽  
Vol 50 (12) ◽  
pp. 1685-1692 ◽  
Author(s):  
John P. Mattson ◽  
Todd A. Miller ◽  
David C. Poole ◽  
Michael D. Delp
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Rank Order ◽  
Oxidative Capacity ◽  
Type I ◽  
Cross Sectional ◽  
Physiological Investigation ◽  
Combining Data ◽  
Type I Fibers

The hamster is a valuable biological model for physiological investigation. Despite the obvious importance of the integration of cardiorespiratory and muscular system function, little information is available regarding hamster muscle fiber type and oxidative capacity, both of which are key determinants of muscle function. The purpose of this investigation was to measure immunohistochemically the relative composition and size of muscle fibers composed of types I, IIA, IIX, and IIB fibers in hamster skeletal muscle. The oxidative capacity of each muscle was also assessed by measuring citrate synthase activity. Twenty-eight hindlimb, respiratory, and facial muscles or muscle parts from adult (144–147 g bw) male Syrian golden hamsters ( n=3) were dissected bilaterally, weighed, and frozen for immunohistochemical and biochemical analysis. Combining data from all 28 muscles analyzed, type I fibers made up 5% of the muscle mass, type IIA fibers 16%, type IIX fibers 39%, and type IIB fibers 40%. Mean fiber cross-sectional area across muscles was 1665 ± 328 μm2 for type I fibers, 1900 ± 417 μm2 for type IIA fibers, 3230 ± 784 μm2 for type IIX fibers, and 4171 ± 864 μm2 for type IIB fibers. Citrate synthase activity was most closely related to the population of type IIA fibers ( r=0.68, p<0.0001) and was in the rank order of type IIA > I > IIX > IIB. These data demonstrate that hamster skeletal muscle is predominantly composed of type IIB and IIX fibers.

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