scholarly journals Skeletal muscle signaling, metabolism, and performance during sprint exercise in severe acute hypoxia after the ingestion of antioxidants

2017 ◽  
Vol 123 (5) ◽  
pp. 1235-1245 ◽  
Author(s):  
David Morales-Alamo ◽  
Borja Guerra ◽  
Jesús Gustavo Ponce-González ◽  
Amelia Guadalupe-Grau ◽  
Alfredo Santana ◽  
...  

The aim of this study was to determine if reactive oxygen species (ROS) could play a role in blunting Thr172-AMP-activated protein kinase (AMPK)-α phosphorylation in human skeletal muscle after sprint exercise in hypoxia and to elucidate the potential signaling mechanisms responsible for this response. Nine volunteers performed a single 30-s sprint (Wingate test) in two occasions while breathing hypoxic gas ([Formula: see text] = 75 mmHg): one after the ingestion of placebo and another following the intake of antioxidants (α-lipoic acid, vitamin C, and vitamin E), with a randomized double-blind design. Vastus lateralis muscle biopsies were obtained before, immediately after, and 30- and 120-min postsprint. Compared with the control condition, the ingestion of antioxidants resulted in lower plasma carbonylated proteins, attenuated elevation of the AMP-to-ATP molar ratio, and reduced glycolytic rate ( P < 0.05) without significant effects on performance or V̇o2. The ingestion of antioxidants did not alter the basal muscle signaling. Thr172-AMPKα and Thr184/187-transforming growth factor-β-activated kinase 1 (TAK1) phosphorylation were not increased after the sprint regardless of the ingestion of antioxidants. Thr286-CaMKII phosphorylation was increased after the sprint, but this response was blunted by the antioxidants. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation increased immediately after the sprints coincident with increased Akt phosphorylation. In summary, antioxidants attenuate the glycolytic response to sprint exercise in severe acute hypoxia and modify the muscle signaling response to exercise. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation, a known mechanism of Thr172-AMPKα phosphorylation inhibition, is increased immediately after sprint exercise in hypoxia, probably by a mechanism independent of ROS. NEW & NOTEWORTHY The glycolytic rate is increased during sprint exercise in severe acute hypoxia. This study showed that the ingestion of antioxidants before sprint exercise in severe acute hypoxia reduced the glycolytic rate and attenuated the increases of the AMP-to-ATP and the reduction of the NAD+-to-NADH.H+ ratios. This resulted in a modified muscle signaling response with a blunted Thr286-CaMKII but similar AMP-activated protein kinase phosphorylation responses in the sprints preceded by the ingestion of antioxidants.

2010 ◽  
Vol 298 (2) ◽  
pp. C377-C385 ◽  
Author(s):  
Jonas T. Treebak ◽  
Eric B. Taylor ◽  
Carol A. Witczak ◽  
Ding An ◽  
Taro Toyoda ◽  
...  

TBC1D4 (also known as AS160) regulates glucose transporter 4 (GLUT4) translocation and glucose uptake in adipocytes and skeletal muscle. Its mode of action involves phosphorylation of serine (S)/threonine (T) residues by upstream kinases resulting in inactivation of Rab-GTPase-activating protein (Rab-GAP) activity leading to GLUT4 mobilization. The majority of known phosphorylation sites on TBC1D4 lie within the Akt consensus motif and are phosphorylated by insulin stimulation. However, the 5′-AMP-activated protein kinase (AMPK) and other kinases may also phosphorylate TBC1D4, and therefore we hypothesized the presence of additional phosphorylation sites. Mouse skeletal muscles were contracted or stimulated with 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), and muscle lysates were subjected to mass spectrometry analyses resulting in identification of novel putative phosphorylation sites on TBC1D4. The surrounding amino acid sequence predicted that S711 would be recognized by AMPK. Using a phosphospecific antibody against S711, we found that AICAR and contraction increased S711 phosphorylation in mouse skeletal muscle, and this increase was abolished in muscle-specific AMPKα2 kinase-dead transgenic mice. Exercise in human vastus lateralis muscle also increased TBC1D4 S711 phosphorylation. Recombinant AMPK, but not Akt1, Akt2, or PKCζ, phosphorylated purified muscle TBC1D4 on S711 in vitro. Interestingly, S711 was also phosphorylated in response to insulin in an Akt2- and rapamycin-independent, but a wortmannin-sensitive, manner, suggesting this site is regulated by one or more additional upstream kinases. Despite increased S711 phosphorylation with AICAR, contraction, and insulin, mutation of S711 to alanine did not alter glucose uptake in response to these stimuli. S711 is a novel TBC1D4 phosphorylation site regulated by AMPK in skeletal muscle.


2012 ◽  
Vol 113 (6) ◽  
pp. 917-928 ◽  
Author(s):  
David Morales-Alamo ◽  
Jesús Gustavo Ponce-González ◽  
Amelia Guadalupe-Grau ◽  
Lorena Rodríguez-García ◽  
Alfredo Santana ◽  
...  

AMP-activated protein kinase (AMPK) is a major mediator of the exercise response and a molecular target to improve insulin sensitivity. To determine if the anaerobic component of the exercise response, which is exaggerated when sprint is performed in severe acute hypoxia, influences sprint exercise-elicited Thr172-AMPKα phosphorylation, 10 volunteers performed a single 30-s sprint (Wingate test) in normoxia and in severe acute hypoxia (inspired Po2: 75 mmHg). Vastus lateralis muscle biopsies were obtained before and immediately after 30 and 120 min postsprint. Mean power output and O2 consumption were 6% and 37%, respectively, lower in hypoxia than in normoxia. O2 deficit and muscle lactate accumulation were greater in hypoxia than in normoxia. Carbonylated skeletal muscle and plasma proteins were increased after the sprint in hypoxia. Thr172-AMPKα phosphorylation was increased by 3.1-fold 30 min after the sprint in normoxia. This effect was prevented by hypoxia. The NAD+-to-NADH.H+ ratio was reduced (by 24-fold) after the sprints, with a greater reduction in hypoxia than in normoxia ( P < 0.05), concomitant with 53% lower sirtuin 1 (SIRT1) protein levels after the sprint in hypoxia ( P < 0.05). This could have led to lower liver kinase B1 (LKB1) activation by SIRT1 and, hence, blunted Thr172-AMPKα phosphorylation. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation, a known negative regulating mechanism of Thr172-AMPKα phosphorylation, was increased by 60% immediately after the sprint in hypoxia, coincident with increased Thr308-Akt phosphorylation. Collectively, our results indicate that the signaling response to sprint exercise in human skeletal muscle is altered in severe acute hypoxia, which abrogated Thr172-AMPKα phosphorylation, likely due to lower LKB1 activation by SIRT1.


1999 ◽  
Vol 87 (5) ◽  
pp. 1668-1673 ◽  
Author(s):  
Marni D. Boppart ◽  
Doron Aronson ◽  
Lindsay Gibson ◽  
Ronenn Roubenoff ◽  
Leslie W. Abad ◽  
...  

Eccentric contractions require the lengthening of skeletal muscle during force production and result in acute and prolonged muscle injury. Because a variety of stressors, including physical exercise and injury, can result in the activation of the c-Jun NH2-terminal kinase (JNK) intracellular signaling cascade in skeletal muscle, we investigated the effects of eccentric exercise on the activation of this stress-activated protein kinase in human skeletal muscle. Twelve healthy subjects (7 men, 5 women) completed maximal concentric or eccentric knee extensions on a KinCom isokinetic dynamometer (10 sets, 10 repetitions). Percutaneous needle biopsies were obtained from the vastus lateralis muscle 24 h before exercise (basal), immediately postexercise, and 6 h postexercise. Whereas both forms of exercise increased JNK activity immediately postexercise, eccentric contractions resulted in a much higher activation (15.4 ± 4.5 vs. 3.5 ± 1.4-fold increase above basal, eccentric vs. concentric). By 6 h after exercise, JNK activity decreased back to baseline values. In contrast to the greater activation of JNK with eccentric exercise, the mitogen-activated protein kinase kinase 4, the immediate upstream regulator of JNK, was similarly activated by concentric and eccentric exercise. Because the activation of JNK promotes the phosphorylation of a variety of transcription factors, including c-Jun, the results from this study suggest that JNK may be involved in the molecular and cellular adaptations that occur in response to injury-producing exercise in human skeletal muscle.


2003 ◽  
Vol 95 (4) ◽  
pp. 1523-1530 ◽  
Author(s):  
Michael J. Christopher ◽  
Zhi-Ping Chen ◽  
Christian Rantzau ◽  
Bruce E. Kemp ◽  
Frank P. Alford

The effect of diabetes and exercise on skeletal muscle (SkM) AMP-activated protein kinase (AMPK)α1 and -α2 activities and site-specific phosphorylation of acetyl-CoA carboxylase was examined in the same six dogs before alloxan (35 mg/kg)-induced diabetes (C) and after 4-5 wk of suboptimally controlled hyperglycemic and hypoinsulinemic diabetes (DHG) in the presence and absence of 300-min phlorizin (50 μg·kg-1·min-1)-induced “normoglycemia” (DNG). In each study, the dog underwent a 150-min [3-3H]glucose infusion period, followed by a 30-min treadmill exercise test (60-70% maximal oxygen capacity) to measure the rate of glucose disposal into peripheral tissues (Rdtissue). SkM biopsies were taken from the thigh (vastus lateralis) before and immediately after exercise. In the C and DHG states, the rise in plasma free fatty acids (FFA) with exercise (∼40%) was similar. In the DNG group, preexercise FFA were significantly higher, but the absolute rise in FFA with exercise was similar. However, the exercise-induced increment in Rdtissue was significantly blunted (by ∼40-50%) in the DNG group compared with the other states. In SkM, preexercise AMPKα1 and -α2 activities were significantly elevated (by ∼60-125%) in both diabetic states, but unlike the C group these activities did not rise further with exercise. Additionally, preexercise acetyl-CoA carboxylase phosphorylation in both diabetic states was elevated by ∼70-80%, but the increases with exercise were similar to the C group. Preexercise AMPKα1 and -α2 activities were negatively correlated with Rdtissue during exercise for the combined groups (both P < 0.02). In conclusion, the elevated preexercise SkM AMPKα1 and -α2 activities contribute to the ongoing basal supply of glucose and fatty acid metabolism in suboptimally controlled hypoinsulinemic diabetic dogs; but whether they also play a permissive role in the metabolic stress response to exercise remains uncertain.


2018 ◽  
Vol 40 (01) ◽  
pp. 16-22 ◽  
Author(s):  
Alberto Pérez-López ◽  
Marcos Martin-Rincon ◽  
Alfredo Santana ◽  
Ismael Perez-Suarez ◽  
Cecilia Dorado ◽  
...  

AbstractInterleukin (IL)-15 stimulates mitochondrial biogenesis, fat oxidation, glucose uptake and myogenesis in skeletal muscle. However, the mechanisms by which exercise triggers IL-15 expression remain to be elucidated in humans. This study aimed at determining whether high-intensity exercise and exercise-induced RONS stimulate IL-15/IL-15Rα expression and its signaling pathway (STAT3) in human skeletal muscle. Nine volunteers performed a 30-s Wingate test in normoxia and hypoxia (PIO2=75 mmHg), 2 h after placebo or antioxidant administration (α-lipoic acid, vitamin C and E) in a randomized double-blind design. Blood samples and muscle biopsies (vastus lateralis) were obtained before, immediately after, and 30 and 120 min post-exercise. Sprint exercise upregulated skeletal muscle IL-15 protein expression (ANOVA, P=0.05), an effect accentuated by antioxidant administration in hypoxia (ANOVA, P=0.022). In antioxidant conditions, the increased IL-15 expression at 120 min post-exercise (33%; P=0.017) was associated with the oxygen deficit caused by the sprint (r=–0.54; P=0.020); while, IL-15 and Tyr705-STAT3 AUCs were also related (r=0.50; P=0.036). Antioxidant administration promotes IL-15 protein expression in human skeletal muscle after sprint exercise, particularly in severe acute hypoxia. Therefore, during intense muscle contraction, a reduced PO2 and glycolytic rate, and possibly, an attenuated RONS generation may facilitate IL-15 production, accompanied by STAT3 activation, in a process that does not require AMPK phosphorylation.


2000 ◽  
Vol 88 (1) ◽  
pp. 352-358 ◽  
Author(s):  
Martin Flück ◽  
M. Neal Waxham ◽  
Marc T. Hamilton ◽  
Frank W. Booth

Spikes in free Ca2+ initiate contractions in skeletal muscle cells, but whether and how they might signal to transcription factors in skeletal muscles of living animals is unknown. Since previous studies in non-muscle cells have shown that serum response factor (SRF) protein, a transcription factor, is phosphorylated rapidly by Ca2+/calmodulin (CaM)-dependent protein kinase after rises in intracellular Ca2+, we measured enzymatic activity that phosphorylates SRF (designated SRF kinase activity). Homogenates from 7-day-hypertrophied anterior latissimus dorsi muscles of roosters had more Ca2+-independent SRF kinase activity than their respective control muscles. However, no differences were noted in Ca2+/CaM-dependent SRF kinase activity between control and trained muscles. To determine whether the Ca2+-independent and Ca2+/CaM-dependent forms of Ca2+/CaM-dependent protein kinase II (CaMKII) might contribute to some of the SRF kinase activity, autocamtide-3, a synthetic substrate that is specific for CaMKII, was employed. While the Ca2+-independent form of CaMKII was increased, like the Ca2+-independent form of SRF kinase, no alteration in CaMKII occurred at 7 days of stretch overload. These observations suggest that some of SRF phosphorylation by skeletal muscle extracts could be due to CaMKII. To determine whether this adaptation was specific to the exercise type (i.e., hypertrophy), similar measurements were made in the white vastus lateralis muscle of rats that had completed 2 wk of voluntary running. Although Ca2+-independent SRF kinase was increased, no alteration occurred in Ca2+/CaM-dependent SRF kinase activity. Thus any role of Ca2+-independent SRF kinase signaling has downstream modulators specific to the exercise phenotype.


2013 ◽  
Vol 114 (5) ◽  
pp. 566-577 ◽  
Author(s):  
David Morales-Alamo ◽  
Jesús Gustavo Ponce-González ◽  
Amelia Guadalupe-Grau ◽  
Lorena Rodríguez-García ◽  
Alfredo Santana ◽  
...  

The extremely high energy demand elicited by sprint exercise is satisfied by an increase in O2 consumption combined with a high glycolytic rate, leading to a marked lactate accumulation, increased AMP-to-ATP ratio, and reduced NAD+/NADH.H+ and muscle pH, which are accompanied by marked Thr172 AMP-activated protein kinase (AMPK)-α phosphorylation during the recovery period by a mechanism not fully understood. To determine the role played by reactive nitrogen and oxygen species (RNOS) on Thr172-AMPKα phosphorylation in response to cycling sprint exercise, nine voluntary participants performed a single 30-s sprint (Wingate test) on two occasions: one 2 h after the ingestion of placebo and another after the intake of antioxidants (α-lipoic acid, vitamin C, and vitamin E) in a double-blind design. Vastus lateralis muscle biopsies were obtained before, immediately postsprint, and 30 and 120 min postsprint. Performance and muscle metabolism were similar during both sprints. The NAD+-to-NADH.H+ ratio was similarly reduced (84%) and the AMP-to-ATP ratio was similarly increased (×21-fold) immediately after the sprints. Thr286 Ca2+/calmodulin-dependent protein kinase II (CaMKII) and Thr172-AMPKα phosphorylations were increased after the control sprint (with placebo) but not when the sprints were preceded by the ingestion of antioxidants. Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation, a known inhibitory mechanism of Thr172-AMPKα phosphorylation, was increased only with antioxidant ingestion. In conclusion, RNOS play a crucial role in AMPK-mediated signaling after sprint exercise in human skeletal muscle. Antioxidant ingestion 2 h before sprint exercise abrogates the Thr172-AMPKα phosphorylation response observed after the ingestion of placebo by reducing CaMKII and increasing Ser485-AMPKα1/Ser491-AMPKα2 phosphorylation. Sprint performance, muscle metabolism, and AMP-to-ATP and NAD+-to-NADH.H+ ratios are not affected by the acute ingestion of antioxidants.


2018 ◽  
Vol 50 (6) ◽  
pp. 416-424 ◽  
Author(s):  
Cameron J. Mitchell ◽  
Randall F. D'Souza ◽  
William Schierding ◽  
Nina Zeng ◽  
Farha Ramzan ◽  
...  

The loss of muscle size, strength, and quality with aging is a major determinant of morbidity and mortality in the elderly. The regulatory pathways that impact the muscle phenotype include the translational regulation maintained by microRNAs (miRNA). Yet the miRNAs that are expressed in human skeletal muscle and relationship to muscle size, strength, and quality are unknown. Using next-generation sequencing, we selected the 50 most abundantly expressed miRNAs and then analyzed them in vastus lateralis muscle, obtained by biopsy from middle-aged males ( n = 48; 50.0 ± 4.3 yr). Isokinetic strength testing and midthigh computed tomography was undertaken for muscle phenotype analysis. Muscle attenuation was measured by computerized tomography and is inversely proportional to myofiber lipid content. miR-486-5p accounted for 21% of total miR sequence reads, with miR-10b-5p, miR-133a-3p, and miR-22-3p accounting for a further 15, 12, and 10%, respectively. Isokinetic knee extension strength and muscle cross-sectional area were positively correlated with miR-100-5p, miR-99b-5p, and miR-191-5p expression. Muscle attenuation was negatively correlated to let-7f-5p, miR-30d-5p, and miR-125b-5p expression. In silico analysis implicates miRNAs related to strength and muscle size in the regulation of mammalian target of rapamycin, while miRNAs related to muscle attenuation may have potential roles regulating the transforming growth factor-β/SMAD3 pathway.


2018 ◽  
Vol 125 (5) ◽  
pp. 1609-1619 ◽  
Author(s):  
Maja Munk Dethlefsen ◽  
Lærke Bertholdt ◽  
Anders Gudiksen ◽  
Tomasz Stankiewicz ◽  
Jens Bangsbo ◽  
...  

The present study aimed at investigating fasting-induced responses in regulators and markers of autophagy in vastus lateralis muscle from untrained and trained human subjects. Untrained and trained subjects (based on maximum oxygen uptake, muscle citrate synthase activity, and oxidative phosphorylation protein level) fasted for 36 h with vastus lateralis muscle biopsies obtained at 2, 12, 24, and 36 h after a standardized meal. Fasting reduced ( P < 0.05) skeletal muscle microtubule-associated protein-1A/1B light chain 3 (LC3)I, LC3II, and adaptor protein sequestosome 1/p62 protein content in untrained subjects only. Moreover, skeletal muscle RAC-alpha serine/threonine-protein kinase (AKT)Thr308, AMP-activated protein kinase (AMPK)Thr172, and Unc-51-like autophagy-activating kinase-1 (ULK1)Ser555 phosphorylation state, as well as Bcl-2-interacting coiled-coil protein-1 (Beclin1) and ULK1Ser757 phosphorylation, was lower ( P < 0.05) in trained than untrained subjects during fasting. In addition, the plasma concentrations of several amino acids were higher ( P < 0.05) in trained than untrained subjects, and the plasma concentration profile of several amino acids was different in untrained and trained subjects during fasting. Taken together, these findings suggest that 36-h fasting has effects on some mediators of autophagy in untrained human skeletal muscle and that training state influences the effect of fasting on autophagy signaling and on mediators of autophagy in skeletal muscle. NEW & NOTEWORTHY This study showed that skeletal muscle autophagy was only modestly affected in humans by 36 h of fasting. Hence, 36-h fasting has effects on some mediators of autophagy in untrained human skeletal muscle, and training state influences the effect of fasting on autophagy signaling and on mediators of autophagy in skeletal muscle.


2017 ◽  
Vol 95 (8) ◽  
pp. 3552
Author(s):  
E. M. England ◽  
H. Shi ◽  
S. K. Matarneh ◽  
E. M. Oliver ◽  
E. T. Helm ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document