Skeletal muscle fiber composition is related to adiposity and in vitro glucose transport rate in humans

Hickey, Matthew S.; Carey, J. O.; Azevedo, J. L.; Houmard, Joseph A.; Pories, Walter J.; Israel, R. G.; Dohm, G. Lynis

doi:10.1152/ajpendo.1995.268.3.e453

Cited by 238 publications

(264 citation statements)

References 18 publications

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“…In the group with type 2 diabetes patients, five of the eight individuals had a family history of diabetes, but at the same time had similar physical activity levels evaluated by the IPAQ to obese and lean controls, and yet the V Á O 2max was lower in patients with type 2 diabetes. The finding of an increased type IIX fibre content in patients with type 2 diabetes has been reported in some [4,36,37] but not all studies [38,39]. In the present study, fibre type distribution in the arm was similar in all groups and the fibre type distribution in lean controls was in agreement with other previously published values [40][41][42].…”

Section: Discussionsupporting

confidence: 92%

Are substrate use during exercise and mitochondrial respiratory capacity decreased in arm and leg muscle in type 2 diabetes?

Larsen¹,

Ara

Rabøl³

et al. 2009

Diabetologia

131

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Aim/hypothesis The aim of the study was to investigate mitochondrial function, fibre type distribution and substrate oxidation in arm and leg muscle during exercise in patients with type 2 diabetes and in obese and lean controls. Methods Indirect calorimetry was used to calculate fat and carbohydrate oxidation during both progressive arm-cranking and leg-cycling exercises. Muscle biopsies from arm and leg were obtained. Fibre type, as well as O 2 flux capacity of saponin-permeabilised muscle fibres were measured, the latter by high resolution respirometry, in patients with type 2 diabetes, age-and BMI-matched obese controls, and agematched lean controls. Results Fat oxidation was similar in the groups during either arm or leg exercise. During leg exercise at higher intensities, but not during arm exercise, carbohydrate oxidation was lower in patients with type 2 diabetes compared with the other groups. In patients with type 2 diabetes, ADP-stimulated state 3 respiration per mg muscle with parallel electron input from complex I+II was lower in m. vastus lateralis compared with obese and lean controls, whereas no differences between groups were present in m. deltoideus. A higher percentage of type IIX fibres was seen in m. vastus lateralis in patients with type 2 diabetes compared with obese and lean controls, whereas no difference was found in the deltoid muscle. Conclusions/interpretation This study demonstrates similar O 2 flux capacity, fibre type distribution and carbohydrate oxidation in arm muscle in the groups despite the presence of attenuated values in leg muscle in patients with type 2 diabetes compared with obese and lean controls.

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Section: Discussionsupporting

confidence: 92%

Are substrate use during exercise and mitochondrial respiratory capacity decreased in arm and leg muscle in type 2 diabetes?

Larsen¹,

Ara

Rabøl³

et al. 2009

Diabetologia

131

View full text Add to dashboard Cite

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“…It has also been shown that myostatin expression in muscle is reduced acutely with endurance and resistance exercise (39). Because physical inactivity and a glycolytic fiber type distribution are common features of obesity, elevated myostatin levels could also be secondary to sedentary lifestyle (40,41). Because insulin resistance is not consistently maintained in primary cultured muscle cells, increased myostatin expression could be an inherent characteristic of the extremely obese (14).…”

Section: Discussionmentioning

confidence: 99%

Increased Secretion and Expression of Myostatin in Skeletal Muscle From Extremely Obese Women

et al. 2009

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OBJECTIVE-Obesity is associated with endocrine abnormalities that predict the progression of insulin resistance to type 2 diabetes. Because skeletal muscle has been shown to secrete proteins that could be used as biomarkers, we characterized the secreted protein profile of muscle cells derived from extremely obese (BMI 48.8 Ϯ 14.8 kg/m 2 ; homeostasis model assessment [HOMA] 3.6 Ϯ 1.0) relative to lean healthy subjects (BMI 25.7 Ϯ 3.2 kg/m 2 ; HOMA 0.8 Ϯ 0.2).RESEARCH DESIGN AND METHODS-We hypothesized that skeletal muscle would secrete proteins that predict the severity of obesity. To test this hypothesis, we used a "bottom-up" experimental design using stable isotope labeling by amino acids in culture (SILAC) and liquid chromatography/mass spectometry/ mass spectometry (LC-MS/MS) to both identify and quantify proteins secreted from cultured myotubes derived from extremely obese compared with healthy nonobese women.RESULTS-Using SILAC, we discovered a 2.9-fold increase in the secretion of myostatin from extremely obese human myotubes. The increased secretion and biological activity of myostatin were validated by immunoblot (3.16 Ϯ 0.18, P Ͻ 0.01) and a myoblast proliferation assay using conditioned growth medium. Myostatin was subsequently shown to increase in skeletal muscle (23%, P Ͻ 0.05) and plasma (35%, P Ͻ 0.05) and to correlate (r 2 ϭ 0.6, P Ͻ 0.05) with the severity of insulin resistance.CONCLUSIONS-Myostatin is a potent antianabolic regulator of muscle mass that may also play a role in energy metabolism. These findings show that increased expression of myostatin in skeletal muscle with obesity and insulin resistance results in elevated circulating myostatin. This may contribute to systemic metabolic deterioration of skeletal muscle with the progression of insulin resistance to type 2 diabetes. Diabetes 58: [30][31][32][33][34][35][36][37][38] 2009 O besity and type 2 diabetes are associated with endocrine abnormalities that are either precipitated by or precede the onset of peripheral insulin resistance (1). These include changes in circulating proteins and peptides that produce endothelial dysfunction, low-grade inflammation, and a prothrombotic state, all of which contribute to increased cardiovascular risk (2-4). Secreted proteins or the "secretome" constitute an important class of biologically active molecules that are released into circulation where they facilitate cross-talk between organ systems. Because secreted proteins are also involved in the progression of cardiovascular disease and cancer, there is significant interest in mining the secretome for novel biological markers (5). Whereas endocrine organs specialize in the secretion of proteins into circulation, there is mounting evidence that adipose tissue and skeletal muscle constitutively or intermittently secrete bioactive proteins (6,7). In this study, we hypothesized that skeletal muscle of extremely obese and insulinresistant women would secrete proteins into circulation that act as prognostic or diagnostic biomarkers of obesityass...

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“…Obese and diabetic patients have reduced oxidative capacity, increased glycolytic capacity and a decreased percentage of type I fibers in muscles [38][39]. Increasing the percentage of oxidative fibers can lead to improved insulin action and reduced adipocyte size [3][4][5].…”

Section: Discussionmentioning

confidence: 99%

TRPV1 activation improves exercise endurance and energy metabolism through PGC-1α upregulation in mice

et al. 2011

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Impaired aerobic exercise capacity and skeletal muscle dysfunction are associated with cardiometabolic diseases. Acute administration of capsaicin enhances exercise endurance in rodents, but the long-term effect of dietary capsaicin is unknown. The capsaicin receptor, the transient receptor potential vanilloid 1 (TRPV1) cation channel has been detected in skeletal muscle, the role of which remains unclear. Here we report the function of TRPV1 in cultured C2C12 myocytes and the effect of TRPV1 activation by dietary capsaicin on energy metabolism and exercise endurance of skeletal muscles in mice. In vitro, capsaicin increased cytosolic free calcium and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) expression in C2C12 myotubes through activating TRPV1. In vivo, PGC-1α in skeletal muscle was upregulated by capsaicin-induced TRPV1 activation or genetic overexpression of TRPV1 in mice. TRPV1 activation increased the expression of genes involved in fatty acid oxidation and mitochondrial respiration, promoted mitochondrial biogenesis, increased oxidative fibers, enhanced exercise endurance and prevented high-fat diet-induced metabolic disorders. Importantly, these effects of capsaicin were absent in TRPV1-deficient mice. We conclude that TRPV1 activation by dietary capsaicin improves energy metabolism and exercise endurance by upregulating PGC-1α in skeletal muscles. The present results indicate a novel therapeutic strategy for managing metabolic diseases and improving exercise endurance.

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Skeletal muscle fiber composition is related to adiposity and in vitro glucose transport rate in humans

Cited by 238 publications

References 18 publications

Are substrate use during exercise and mitochondrial respiratory capacity decreased in arm and leg muscle in type 2 diabetes?

Are substrate use during exercise and mitochondrial respiratory capacity decreased in arm and leg muscle in type 2 diabetes?

Increased Secretion and Expression of Myostatin in Skeletal Muscle From Extremely Obese Women

TRPV1 activation improves exercise endurance and energy metabolism through PGC-1α upregulation in mice

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