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Shu JJ, Harter TS, Morrison PR, Brauner CJ. Enhanced hemoglobin-oxygen unloading in migratory salmonids. J Comp Physiol B 2017; 188:409-419. [PMID: 29218398 DOI: 10.1007/s00360-017-1139-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/20/2017] [Accepted: 11/27/2017] [Indexed: 11/28/2022]
Abstract
Recent findings indicate that some teleost fishes may be able to greatly enhance hemoglobin-oxygen (Hb-O2) unloading at the tissues under conditions that result in catecholamine release. The putative mechanism relies on the high pH sensitivity of teleost hemoglobin (Hb), intracellular red blood cell (RBC) pH regulation via β-adrenergic Na+/H+ exchanger (β-NHE) activity, and plasma-accessible carbonic anhydrase at the tissues that short-circuits RBC pH regulation. Previous studies have shown that in rainbow trout, this system may double Hb-O2 unloading to red muscle compared to a situation without short-circuiting. The present study determined that: (1) in rainbow trout this system may be functional even at low concentrations of circulating catecholamines, as shown by conducting a dose-response analysis; (2) Atlantic and coho salmon also possess β-NHE activity, as shown by changes in hematocrit in adrenergically stimulated cells; and (3) with β-NHE short-circuiting, Atlantic and coho salmon may be able to increase Hb-O2 unloading by up to 74 and 159%, respectively, as determined by modeling based on O2 equilibrium curves. Together, these results indicate that a system to enhance Hb-O2 unloading may be common among salmonids and may be operational even under routine conditions. In view of the life histories of Atlantic and coho salmon, a system to enhance Hb-O2 unloading during exercise may help determine a successful spawning migration and thus reproductive success.
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Affiliation(s)
- Jacelyn J Shu
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Till S Harter
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Phillip R Morrison
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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2
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Zanou N, Mondin L, Fuster C, Seghers F, Dufour I, de Clippele M, Schakman O, Tajeddine N, Iwata Y, Wakabayashi S, Voets T, Allard B, Gailly P. Osmosensation in TRPV2 dominant negative expressing skeletal muscle fibres. J Physiol 2015; 593:3849-63. [PMID: 26108786 DOI: 10.1113/jp270522] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 06/19/2015] [Indexed: 11/08/2022] Open
Abstract
Increased plasma osmolarity induces intracellular water depletion and cell shrinkage (CS) followed by activation of a regulatory volume increase (RVI). In skeletal muscle, the hyperosmotic shock-induced CS is accompanied by a small membrane depolarization responsible for a release of Ca(2+) from intracellular pools. Hyperosmotic shock also induces phosphorylation of STE20/SPS1-related proline/alanine-rich kinase (SPAK). TRPV2 dominant negative expressing fibres challenged with hyperosmotic shock present a slower membrane depolarization, a diminished Ca(2+) response, a smaller RVI response, a decrease in SPAK phosphorylation and defective muscle function. We suggest that hyperosmotic shock induces TRPV2 activation, which accelerates muscle cell depolarization and allows the subsequent Ca(2+) release from the sarcoplasmic reticulum, activation of the Na(+) -K(+) -Cl(-) cotransporter by SPAK, and the RVI response. Increased plasma osmolarity induces intracellular water depletion and cell shrinkage followed by activation of a regulatory volume increase (RVI). In skeletal muscle, this is accompanied by transverse tubule (TT) dilatation and by a membrane depolarization responsible for a release of Ca(2+) from intracellular pools. We observed that both hyperosmotic shock-induced Ca(2+) transients and RVI were inhibited by Gd(3+) , ruthenium red and GsMTx4 toxin, three inhibitors of mechanosensitive ion channels. The response was also completely absent in muscle fibres overexpressing a non-permeant, dominant negative (DN) mutant of the transient receptor potential, V2 isoform (TRPV2) ion channel, suggesting the involvement of TRPV2 or of a TRP isoform susceptible to heterotetramerization with TRPV2. The release of Ca(2+) induced by hyperosmotic shock was increased by cannabidiol, an activator of TRPV2, and decreased by tranilast, an inhibitor of TRPV2, suggesting a role for the TRPV2 channel itself. Hyperosmotic shock-induced membrane depolarization was impaired in TRPV2-DN fibres, suggesting that TRPV2 activation triggers the release of Ca(2+) from the sarcoplasmic reticulum by depolarizing TTs. RVI requires the sequential activation of STE20/SPS1-related proline/alanine-rich kinase (SPAK) and NKCC1, a Na(+) -K(+) -Cl(-) cotransporter, allowing ion entry and driving osmotic water flow. In fibres overexpressing TRPV2-DN as well as in fibres in which Ca(2+) transients were abolished by the Ca(2+) chelator BAPTA, the level of P-SPAK(Ser373) in response to hyperosmotic shock was reduced, suggesting a modulation of SPAK phosphorylation by intracellular Ca(2+) . We conclude that TRPV2 is involved in osmosensation in skeletal muscle fibres, acting in concert with P-SPAK-activated NKCC1.
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Affiliation(s)
- Nadège Zanou
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Ludivine Mondin
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Clarisse Fuster
- Centre de Génétique et de Physiologie Cellulaire et Moléculaire, Université Claude Bernard Lyon 1, CNRS, UMR 5534, 69622, Villeurbanne, France
| | - François Seghers
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Inès Dufour
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Marie de Clippele
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Olivier Schakman
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Nicolas Tajeddine
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
| | - Yuko Iwata
- Department of Molecular Physiology, National Cardiovascular Center Research Institute Suita, Osaka, 565-8565, Japan
| | - Shigeo Wakabayashi
- Department of Molecular Physiology, National Cardiovascular Center Research Institute Suita, Osaka, 565-8565, Japan
| | - Thomas Voets
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, Katholiek Universiteit Leuven, B-3000, Leuven, Belgium
| | - Bruno Allard
- Centre de Génétique et de Physiologie Cellulaire et Moléculaire, Université Claude Bernard Lyon 1, CNRS, UMR 5534, 69622, Villeurbanne, France
| | - Philippe Gailly
- Laboratory of Cell Physiology, Institute of Neuroscience, Université catholique de Louvain, av. Mounier, B1.53.17, B-1200, Brussels, Belgium
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3
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Dahle MK, Wessel Ø, Timmerhaus G, Nyman IB, Jørgensen SM, Rimstad E, Krasnov A. Transcriptome analyses of Atlantic salmon (Salmo salar L.) erythrocytes infected with piscine orthoreovirus (PRV). FISH & SHELLFISH IMMUNOLOGY 2015; 45:780-790. [PMID: 26057463 DOI: 10.1016/j.fsi.2015.05.049] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/24/2015] [Accepted: 05/29/2015] [Indexed: 06/04/2023]
Abstract
Heart and skeletal muscle inflammation (HSMI) is a widespread disease of farmed Atlantic salmon (Salmo salar L.) and is associated with piscine orthoreovirus (PRV) infection. PRV is detectable in blood long before development of pathology in cardiac- and skeletal muscle appear, and erythrocytes have been identified as important target cells for the virus. The effects of PRV infection on cellular processes of erythrocytes are not known, but haemolytic anemia or systemic lysis of erythrocytes does not seem to occur, even with high virus loads in erythrocytes. In this study, gene expression profiling performed with high-density oligonucleotide microarray showed that PRV infection of erythrocytes induced a large panel of virus responsive genes. These involved interferon-regulated antiviral genes, as well as genes involved in antigen presentation via MHC class I. PRV infection also stimulated negative immune regulators. In contrast, a large number of immune genes expressed prior to infection were down-regulated. Moderate reduction of expression was also found for many genes encoding components of cytoskeleton and myofiber, proteins involved in metabolism, ion exchange, cell-cell interactions as well as growth factors and regulators of differentiation. PRV did not affect expression of genes involved in heme biosynthesis, gas exchange or erythrocyte-specific markers, but some regulators of erythropoiesis showed decreased transcription levels. These results indicate that PRV infection activates innate antiviral immunity in salmon erythrocytes, but suppresses other gene expression programs. Gene expression profiles suggest major phenotypic changes in PRV infected erythrocytes, but the functional consequences remain to be explored.
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Affiliation(s)
| | - Øystein Wessel
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Gerrit Timmerhaus
- Nofima AS, Norwegian Institutes of Food, Fisheries & Aquaculture Research, Ås, Norway
| | - Ingvild Berg Nyman
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Sven Martin Jørgensen
- Nofima AS, Norwegian Institutes of Food, Fisheries & Aquaculture Research, Ås, Norway
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Aleksei Krasnov
- Nofima AS, Norwegian Institutes of Food, Fisheries & Aquaculture Research, Ås, Norway.
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Abstract
Organisms exposed to altered salinity must be able to perceive osmolality change because metabolism has evolved to function optimally at specific intracellular ionic strength and composition. Such osmosensing comprises a complex physiological process involving many elements at organismal and cellular levels of organization. Input from numerous osmosensors is integrated to encode magnitude, direction, and ionic basis of osmolality change. This combinatorial nature of osmosensing is discussed with emphasis on fishes.
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Affiliation(s)
- Dietmar Kültz
- Department of Animal Science, Physiological Genomics Group, University of California, Davis, Davis, California
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