scholarly journals Measurement of nitrate and nitrite in biopsy-sized muscle samples using HPLC

2018 ◽  
Vol 125 (5) ◽  
pp. 1475-1481 ◽  
Author(s):  
Ashley D. Troutman ◽  
Edgar J. Gallardo ◽  
Mary Beth Brown ◽  
Andrew R. Coggan
Keyword(s):  
Skeletal Muscle ◽  
Whole Body ◽  
Oxidoreductase Activity ◽  
Bead Beating ◽  
Health And Disease ◽  
Text Content ◽  
Nitrate And Nitrite ◽  
Triton X ◽  
Mechanical Homogenization

Studies of rats have indicated that skeletal muscle plays a central role in whole-body nitrate ([Formula: see text])/nitrite ([Formula: see text])/nitric oxide (NO) metabolism. Extending these results to humans, however, is challenging due to the small size of needle biopsy samples. We therefore developed a method to precisely and accurately quantify [Formula: see text] and [Formula: see text] in biopsy-sized muscle samples. [Formula: see text] and [Formula: see text] were extracted from rat soleus samples using methanol combined with mechanical homogenization + ultrasound, bead beating, pulverization at liquid N2temperature or pulverization + 0.5% Triton X-100. After centrifugation to remove proteins, [Formula: see text] and [Formula: see text] were measured using HPLC. Mechanical homogenization + ultrasound resulted in the lowest [Formula: see text] content (62 ± 20 pmol/mg), with high variability [coefficient of variation (CV) >50%] across samples from the same muscle. The [Formula: see text]/[Formula: see text] ratio (0.019 ± 0.006) was also elevated, suggestive of [Formula: see text] reduction during tissue processing. Bead beating or pulverization yielded lower [Formula: see text] and slightly higher [Formula: see text] levels, but reproducibility was still poor. Pulverization + 0.5% Triton X-100 provided the highest [Formula: see text] content (124 ± 12 pmol/mg) and lowest [Formula: see text]/[Formula: see text] ratio (0.008 ± 0.001), with the least variability between duplicate samples (CV ~15%). These values are consistent with literature data from larger rat muscle samples analyzed using chemiluminescence. Samples were stable for at least 5 wk at −80°C, provided residual xanthine oxidoreductase activity was blocked using 0.1 mmol/l oxypurinol. We have developed a method capable of measuring [Formula: see text] and [Formula: see text] in <1 mg of muscle. This method should prove highly useful in investigating the role of skeletal muscle in [Formula: see text]/[Formula: see text]/NO metabolism in human health and disease.NEW & NOTEWORTHY Measurement of nitrate and especially nitrite in small, i.e., biopsy-sized, muscle samples is analytically challenging. We have developed a precise, accurate, and convenient method for doing so using an affordable commercial HPLC system.

Determinants of maximal whole-body fat oxidation in elite cross-country skiers: Role of skeletal muscle mitochondria

2018 ◽  
Vol 28 (12) ◽  
pp. 2494-2504 ◽  
Author(s):  
Sune Dandanell ◽  
Anne-Kristine Meinild-Lundby ◽  
Andreas B. Andersen ◽  
Paul F. Lang ◽  
Laura Oberholzer ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Body Fat ◽  
Fat Oxidation ◽  
Whole Body ◽  
Muscle Mitochondria ◽  
Skeletal Muscle Mitochondria ◽  
Cross Country

scholarly journals Mechanisms of sympathetic restraint in human skeletal muscle during exercise: role of α-adrenergic and nonadrenergic mechanisms

2020 ◽  
Vol 319 (1) ◽  
pp. H192-H202
Author(s):  
Alexander B. Hansen ◽  
Gilbert Moralez ◽  
Steven A. Romero ◽  
Christopher Gasho ◽  
Michael M. Tymko ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adrenergic Receptors ◽  
Whole Body ◽  
Cycle Exercise ◽  
Vascular Conductance ◽  
Hand Grip ◽  
Vasodilatory Response ◽  
Sympathetic Vasoconstriction ◽  
Exercise Induced

Sympathetic restraint of vascular conductance to inactive skeletal muscle is critical to maintain blood pressure during moderate- to high-intensity whole body exercise. This investigation shows that cycle exercise-induced restraint of inactive skeletal muscle vascular conductance occurs primarily because of activation of α-adrenergic receptors. Furthermore, exercise-induced vasoconstriction restrains the subsequent vasodilatory response to hand-grip exercise; however, the restraint of active skeletal muscle vasodilation was in part due to nonadrenergic mechanisms. We conclude that α-adrenergic receptors are the primary but not exclusive mechanism by which sympathetic vasoconstriction restrains blood flow in humans during whole body exercise and that metabolic activity modulates the contribution of α-adrenergic receptors.

ROLE OF NA+, K+-ATPase IN MUSCULAR ENERGY EXPENDITURE OF WARM- AND COLD-EXPOSED SHEEP

1982 ◽  
Vol 62 (1) ◽  
pp. 123-132 ◽  
Author(s):  
V. A. GREGG ◽  
L. P. MILLIGAN
Keyword(s):  
Skeletal Muscle ◽  
Energy Expenditure ◽  
Cold Exposure ◽  
Whole Body ◽  
Random Group ◽  
Key Words Skeletal Muscle ◽  
Maximum Inhibition ◽  
Functional Membrane

The role of Na+, K+-ATPase in the energy expenditure of sheep skeletal muscle and the influence of exposure to cold on this role were studied. An in vitro preparation of muscle was developed that achieved O2 availability and a functional membrane potential. A 10−6 M concentration of ouabain yielded a maximum inhibition of respiration of 38.9 ± 1.8% using muscle preparations from a random group of sheep. Whole body and muscle O2 consumptions and ouabain-sensitive muscle respiration were measured for warm- and cold-exposed sheep fed at maintenance or 1150 g of alfalfa pellets per day. Cold exposure increased whole body and muscle O2 consumption. Inhibition of respiration by ouabain was 37.6 ± 1.2% and 41.0 ± 3.6% for warm- and cold-exposed sheep fed at maintenance, and 28.5 ± 4.0% and 45.0 ± 4.0% for warm- and cold-exposed sheep fed 1150 g of alfalfa pellets per day. The increase in the ouabain-sensitive component of respiration accounted for 48–79% of the increased O2 consumption of muscle from cold-exposed sheep. It was concluded that the Na+, K+-ATPase of sheep muscle is a major means of energy expenditure and has an important role in the increased thermogenesis resulting from cold exposure. Key words: Skeletal muscle, Energy expenditure, muscle respiration, cold thermogenesis, sodium-potassium transport

scholarly journals Neuropeptide Y and neurovascular control in skeletal muscle and skin

2009 ◽  
Vol 297 (3) ◽  
pp. R546-R555 ◽  
Author(s):  
Gary J. Hodges ◽  
Dwayne N. Jackson ◽  
Louis Mattar ◽  
John M. Johnson ◽  
J. Kevin Shoemaker
Keyword(s):  
Skeletal Muscle ◽  
Neuropeptide Y ◽  
Receptor Activation ◽  
Female Rats ◽  
Whole Body ◽  
Vasomotor Tone ◽  
Local Cooling ◽  
Vascular Conductance ◽  
Vasoactive Agent

Neuropeptide Y (NPY) is a ubiquitous peptide with multiple effects on energy metabolism, reproduction, neurogenesis, and emotion. In addition, NPY is an important sympathetic neurotransmitter involved in neurovascular regulation. Although early studies suggested that the vasoactive effects of NPY were limited to periods of high stress, there is growing evidence for the involvement of NPY on baseline vasomotor tone and sympathetically evoked vasoconstriction in vivo in both skeletal muscle and the cutaneous circulation. In Sprague-Dawley rat skeletal muscle, Y1-receptor activation appears to play an important role in the regulation of basal vascular conductance, and this effect is similar in magnitude to the α1-receptor contribution. Furthermore, under baseline conditions, agonist and receptor-based mechanisms for Y1-receptor-dependent control of vascular conductance in skeletal muscle are greater in male than female rats. In skin, there is Y1-receptor-mediated vasoconstriction during whole body, but not local, cooling. As with the NPY system in muscle, this neural effect in skin differs between males and females and in addition, declines with aging. Intriguingly, skin vasodilation to local heating also requires NPY and is currently thought to be acting via a nitric oxide pathway. These studies are establishing further interest in the role of NPY as an important vasoactive agent in muscle and skin, adding to the complexity of neurovascular regulation in these tissues. In this review, we focus on the role of NPY on baseline vasomotor tone in skeletal muscle and skin and how NPY modulates vasomotor tone in response to stress, with the aim of compiling what is currently known, while highlighting some of the more pertinent questions yet to be answered.

scholarly journals Skeletal Muscle Na,K-ATPase as a Target for Circulating Ouabain

2020 ◽  
Vol 21 (8) ◽  
pp. 2875 ◽  
Author(s):  
Violetta V. Kravtsova ◽  
Elena V. Bouzinova ◽  
Vladimir V. Matchkov ◽  
Igor I. Krivoi
Keyword(s):  
Skeletal Muscle ◽  
Diaphragm Muscle ◽  
Hindlimb Suspension ◽  
Resting Potential ◽  
Human Red Blood Cells ◽  
Central Nervous Systems ◽  
Health And Disease ◽  
Specific Increase ◽  
20 Nm

While the role of circulating ouabain-like compounds in the cardiovascular and central nervous systems, kidney and other tissues in health and disease is well documented, little is known about its effects in skeletal muscle. In this study, rats were intraperitoneally injected with ouabain (0.1–10 µg/kg for 4 days) alone or with subsequent injections of lipopolysaccharide (1 mg/kg). Some rats were also subjected to disuse for 6 h by hindlimb suspension. In the diaphragm muscle, chronic ouabain (1 µg/kg) hyperpolarized resting potential of extrajunctional membrane due to specific increase in electrogenic transport activity of the α2 Na,K-ATPase isozyme and without changes in α1 and α2 Na,K-ATPase protein content. Ouabain (10–20 nM), acutely applied to isolated intact diaphragm muscle from not injected rats, hyperpolarized the membrane to a similar extent. Chronic ouabain administration prevented lipopolysaccharide-induced (diaphragm muscle) or disuse-induced (soleus muscle) depolarization of the extrajunctional membrane. No stimulation of the α1 Na,K-ATPase activity in human red blood cells, purified lamb kidney and Torpedo membrane preparations by low ouabain concentrations was observed. Our results suggest that skeletal muscle electrogenesis is subjected to regulation by circulating ouabain via the α2 Na,K-ATPase isozyme that could be important for adaptation of this tissue to functional impairment.

scholarly journals Increased glucose metabolism in Arid5b−/− skeletal muscle is associated with the down-regulation of TBC1 domain family member 1 (TBC1D1)

2020 ◽  
Vol 53 (1) ◽  
Author(s):  
Yuri Okazaki ◽  
Jennifer Murray ◽  
Ali Ehsani ◽  
Jessica Clark ◽  
Robert H. Whitson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Energy Metabolism ◽  
Glucose Metabolism ◽  
Family Member ◽  
Glucose Transporter ◽  
Whole Body ◽  
Domain Family ◽  
Glucose Transporter 1

Abstract Background Skeletal muscle has an important role in regulating whole-body energy homeostasis, and energy production depends on the efficient function of mitochondria. We demonstrated previously that AT-rich interactive domain 5b (Arid5b) knockout (Arid5b−/−) mice were lean and resistant to high-fat diet (HFD)-induced obesity. While a potential role of Arid5b in energy metabolism has been suggested in adipocytes and hepatocytes, the role of Arid5b in skeletal muscle metabolism has not been studied. Therefore, we investigated whether energy metabolism is altered in Arid5b−/− skeletal muscle. Results Arid5b−/− skeletal muscles showed increased basal glucose uptake, glycogen content, glucose oxidation and ATP content. Additionally, glucose clearance and oxygen consumption were upregulated in Arid5b−/− mice. The expression of glucose transporter 1 (GLUT1) and 4 (GLUT4) in the gastrocnemius (GC) muscle remained unchanged. Intriguingly, the expression of TBC domain family member 1 (TBC1D1), which negatively regulates GLUT4 translocation to the plasma membrane, was suppressed in Arid5b−/− skeletal muscle. Coimmunofluorescence staining of the GC muscle sections for GLUT4 and dystrophin revealed increased GLUT4 localization at the plasma membrane in Arid5b−/− muscle. Conclusions The current study showed that the knockout of Arid5b enhanced glucose metabolism through the downregulation of TBC1D1 and increased GLUT4 membrane translocation in skeletal muscle.

scholarly journals Muscling in on mitochondrial sexual dimorphism; role of mitochondrial dimorphism in skeletal muscle health and disease

2017 ◽  
Vol 131 (15) ◽  
pp. 1919-1922 ◽  
Author(s):  
Gareth A. Nye ◽  
Giorgos K. Sakellariou ◽  
Hans Degens ◽  
Adam P. Lightfoot
Keyword(s):  
Skeletal Muscle ◽  
Sexual Dimorphism ◽  
Mitochondrial Function ◽  
Recent Article ◽  
Cellular Processes ◽  
Wide Range ◽  
Health And Disease ◽  
Muscle Health ◽  
The Impact

Mitochondria are no longer solely regarded as the cellular powerhouse; instead, they are now implicated in mediating a wide-range of cellular processes, in the context of health and disease. A recent article in Clinical Science, Ventura-Clapier et al. highlights the role of sexual dimorphism in mitochondrial function in health and disease. However, we feel the authors have overlooked arguably one of the most mitochondria-rich organs in skeletal muscle. Many studies have demonstrated that mitochondria have a central role in mediating the pathogenesis of myopathologies. However, the impact of sexual dimorphism in this context is less clear, with several studies reporting conflicting observations. For instance in ageing studies, a rodent model reported female muscles have higher antioxidant capacity compared with males; in contrast, human studies demonstrate no sex difference in mitochondrial bioenergetics and oxidative damage. These divergent observations highlight the importance of considering models and methods used to examine mitochondrial function, when interpreting these data. The use of either isolated or intact mitochondrial preparations in many studies appears likely to be a source of discord, when comparing many studies. Overall, it is now clear that more research is needed to determine if sexual dimorphism is a contributing factor in the development of myopathologies.

scholarly journals Role of Adenosine 5′-Monophosphate-Activated Protein Kinase in Interleukin-6 Release from Isolated Mouse Skeletal Muscle

Endocrinology ◽  
2009 ◽  
Vol 150 (2) ◽  
pp. 600-606 ◽  
Author(s):  
Stephan Glund ◽  
Jonas T. Treebak ◽  
Yun Chau Long ◽  
Romain Barres ◽  
Benoit Viollet ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Extensor Digitorum Longus ◽  
Protein Release ◽  
Extensor Digitorum ◽  
Whole Body ◽  
Wild Type ◽  
Amp Activated Protein Kinase ◽  
Respective Wild Type

IL-6 is released from skeletal muscle during exercise and has consequently been implicated to mediate beneficial effects on whole-body metabolism. Using 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR), a pharmacological activator of 5′-AMP-activated protein kinase (AMPK), we tested the hypothesis that AMPK modulates IL-6 release from isolated muscle. Skeletal muscle from AMPKα2 kinase-dead transgenic, AMPKα1 knockout (KO) and AMPKγ3 KO mice and respective wild-type littermates was incubated in vitro, in the absence or presence of 2 mmol/liter AICAR. Skeletal muscle from wild-type mice was also incubated with the AMPK activator A-769662. Incubation of mouse glycolytic extensor digitorum longus and oxidative soleus muscle for 2 h was associated with profound IL-6 mRNA production and protein release, which was suppressed by AICAR (P &lt; 0.001). Basal IL-6 release from soleus was increased between AMPKα2 kinase-dead and AMPKα1 KO and their respective wild-type littermates (P &lt; 0.05), suggesting AMPK participates in the regulation of IL-6 release from oxidative muscle. The effect of AICAR on muscle IL-6 release was similar between AMPKα2 KD, AMPKα1 KO, and AMPKγ3 KO mice and their respective wild-type littermates (P &lt; 0.001), indicating AICAR-mediated suppression of IL-6 mRNA expression and protein release is independent of AMPK function. However, IL-6 release from soleus, but not extensor digitorum longus, was reduced 45% by A-769662. Our results on basal and A-769662-mediated IL-6 release provide evidence for a role of AMPK in the regulation of IL-6 release from oxidative skeletal muscle. Furthermore, in addition to activating AMPK, AICAR suppresses IL-6 release by an unknown, AMPK-independent mechanism. Using transgenic and knockout mouse models to perturb AMP-activated protein kinase (AMPK) signaling, we provide evidence that AMPK-dependent pathways regulate IL-6 release from isolated oxidative skeletal muscle.

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