Reactive oxygen species are important mediators of  taurine release from skeletal muscle cells

Ørtenblad, Niels; Young, Jette F.; Oksbjerg, Niels; Nielsen, Jacob Holm; Lambert, Ian Henry

doi:10.1152/ajpcell.00287.2002

Cited by 76 publications

(79 citation statements)

References 44 publications

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“…[26][27][28] Similarly, taurine is known to play important roles against reactive oxygen species and hypoxia in several organs, including the those of the CNS and the vasculature. [29][30][31][32][33] Both intermittent hypoxia and increased oxidative stress are hallmark characteristics of OSA, 34 and the degree of oxidative stress associated with OSA has emerged as an important determinant of cognitive dysfunction in both animal models and in children. [35][36][37] A unique and intriguing observation in the present study involves the differential and predictable changes in urinary neurotransmitters in children with OSA and without evidence of neurocognitive dysfunction.…”

Section: Discussionmentioning

confidence: 99%

Urinary Neurotransmitters Are Selectively Altered in Children With Obstructive Sleep Apnea and Predict Cognitive Morbidity

Kheirandish‐Gozal

McManus²,

Kellermann³

et al. 2013

Chest

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Snoring is a very frequent complaint affecting 10% to 12% of all children 1 and is the primary symptom of obstructive sleep apnea (OSA). OSA is the occurrence of repeated events of partial or complete upper airway obstruction during sleep, leading to disruption of normal ventilation, and to hypoxemia and sleep fragmentation. The pathophysiology of pediatric OSA is multifactorial, but adenotonsillar hypertrophy with or without concurrent obesity constitutes the major pathophysiologic mechanism underlying OSA in children. 2 Pediatric OSA has been extensively associated with an increased risk for behavioral and mood disturbances, as well as with cognitive defi cits. Furthermore, cardiovascular and metabolic morbidities, such as pulmonary hypertension, systemic hypertension, endothelial dysfunction, insulin resistance, and serum lipid alterations, are also frequently observed. 3 However, identifi cation of those children who have developed any such OSAassociated morbidities is diffi cult, and is usually complicated by the need for laborious and onerous test batteries that are not routinely available in most clinical settings. Therefore, such assessments are usually not pursued.Background: Pediatric obstructive sleep apnea (OSA) is associated with cognitive dysfunction, suggesting altered neurotransmitter function. We explored overnight changes in neurotransmitters in the urine of children with and without OSA. Methods: Urine samples were collected from children with OSA and from control subjects before and after sleep studies. A neurocognitive battery assessing general cognitive ability (GCA) was administered to a subset of children with OSA. Samples were subjected to multiple enzyme-linked immunosorbent assays for 12 neurotransmitters, and adjusted for creatinine concentrations. Results: The study comprised 50 children with OSA and 20 control subjects. Of the children with OSA, 20 had normal GCA score (mean Ϯ SD) (101.2 Ϯ 14.5) and 16 had a reduced GCA score (87.3 Ϯ 13.9; P , .001). Overnight increases in epinephrine, norepinephrine, and g -aminobutyric acid (GABA) levels emerged in children with OSA; taurine levels decreased. Using combinatorial approaches and cutoff values for overnight changes of these four neurotransmitters enabled prediction of OSA (area under the curve [AUC]: 0.923; P , .0001). Furthermore, GABA and taurine alterations, as well as overnight reductions in phenylethylamine, were more prominent in children with OSA and low GCA than in children with OSA and normal GCA ( P , .001), and they reliably discriminated GCA status (AUC: 0.977; P , .0001). Conclusions: Pediatric OSA is associated with overnight increases in urinary concentrations of catecholamines indicative of heightened sympathetic outfl ow. Increases in GABA levels and decreases in taurine levels could underlie mechanisms of neuronal excitotoxicity and dysfunction. Combinatorial approaches using defi ned cutoffs in overnight changes in concentrations of selected neurotransmitters in urine may not only predict OSA but also the presence ...

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Section: Discussionmentioning

confidence: 99%

Urinary Neurotransmitters Are Selectively Altered in Children With Obstructive Sleep Apnea and Predict Cognitive Morbidity

Kheirandish‐Gozal

McManus²,

Kellermann³

et al. 2013

Chest

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“…ROS production increases within the first minutes following hypotonic exposure in, e.g., NIH3T3 fibroblasts (492), skeletal muscle (753), and hepatocytes (1031). The swellinginduced ROS production in HTC cells is reduced in the presence of the NADPH oxidase inhibitor diphenyl iodonium (DPI).…”

Section: Effect Of Cell Volume Perturbations On Cellular Ros Productionmentioning

confidence: 99%

Physiology of Cell Volume Regulation in Vertebrates

Hoffmann

Lambert²,

Pedersen³

2009

Physiological Reviews

1,282

1,677

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The ability to control cell volume is pivotal for cell function. Cell volume perturbation elicits a wide array of signaling events, leading to protective (e.g., cytoskeletal rearrangement) and adaptive (e.g., altered expression of osmolyte transporters and heat shock proteins) measures and, in most cases, activation of volume regulatory osmolyte transport. After acute swelling, cell volume is regulated by the process of regulatory volume decrease (RVD), which involves the activation of KCl cotransport and of channels mediating K+, Cl−, and taurine efflux. Conversely, after acute shrinkage, cell volume is regulated by the process of regulatory volume increase (RVI), which is mediated primarily by Na+/H+exchange, Na+-K+-2Cl−cotransport, and Na+channels. Here, we review in detail the current knowledge regarding the molecular identity of these transport pathways and their regulation by, e.g., membrane deformation, ionic strength, Ca2+, protein kinases and phosphatases, cytoskeletal elements, GTP binding proteins, lipid mediators, and reactive oxygen species, upon changes in cell volume. We also discuss the nature of the upstream elements in volume sensing in vertebrate organisms. Importantly, cell volume impacts on a wide array of physiological processes, including transepithelial transport; cell migration, proliferation, and death; and changes in cell volume function as specific signals regulating these processes. A discussion of this issue concludes the review.

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“…Ørtenblad et al 77) used excised muscle tissue and labeled taurine ( 14 C-taurine) to prove that contracting muscles release taurine upon stimulation with melittin, a toxin that facilitates production of reactive oxygen species via activation of phospholipase A2, or upon anoxic stimulation. Inhibition of taurine release by antioxidants such as vitamin E was also confirmed.…”

Section: Taurinementioning

confidence: 99%

“…Inhibition of taurine release by antioxidants such as vitamin E was also confirmed. Considering the anoxic conditions of muscles and increased oxidative stress during exercise, it can be said that the study by Ørtenblad et al 77) revealed a part of the mechanism underlying exercise-induced taurine release from muscles into the bloodstream.…”

Section: Taurinementioning

confidence: 99%

Exercise-induced changes in amino acid levels in skeletal muscle and plasma

Ishikura¹,

Ra²,

Ohmori³

2013

JPFSM

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During exercise, amino acid oxidation and protein breakdown are enhanced while protein synthesis is suppressed, even though protein does not constitute a quantitatively important energy source. In response to exercise-induced stimulation, various changes in free amino acids occur in skeletal muscle to meet physiological demands. Plasma amino acids are also under the influence of various types of stress, including exercise stress. For example, acute exercise increases alanine and glutamine levels, but decreases glutamate levels in skeletal muscle. At the same time, it increases tryptophan and taurine levels, but decreases glutamine levels in plasma. Prolonged exercise decreases glutamine and glutamate levels, while increasing tyrosine and phenylalanine levels in skeletal muscle. Furthermore, when prolonged exercise-induced changes in amino acid levels are compared between trained and untrained individuals, glutamate and taurine levels in skeletal muscle and phenylalanine, leucine, isoleucine, and tyrosine levels in plasma are higher in trained individuals. This review provides an overview of changes in amino acid levels in skeletal muscle and plasma, with a focus on changes induced by exercise.

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Reactive oxygen species are important mediators of taurine release from skeletal muscle cells

Cited by 76 publications

References 44 publications

Urinary Neurotransmitters Are Selectively Altered in Children With Obstructive Sleep Apnea and Predict Cognitive Morbidity

Urinary Neurotransmitters Are Selectively Altered in Children With Obstructive Sleep Apnea and Predict Cognitive Morbidity

Physiology of Cell Volume Regulation in Vertebrates

Exercise-induced changes in amino acid levels in skeletal muscle and plasma

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