Rapid modulation of Na+/K+-ATPase activity in osmoregulatory tissues of a salmonid fish

Christian Kølbæk Tipsmark, Steffen Madsen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Udgivelsesdato: 2001-Feb
OriginalsprogEngelsk
TidsskriftJournal of Experimental Biology
Vol/bind204
Udgave nummerPt 4
Sider (fra-til)701-709
ISSN0022-0949
StatusUdgivet - 1. feb. 2001

Fingeraftryk

sodium-potassium-exchanging ATPase
salmonid
forskolin
gills
Fishes
Colforsin
cyclic AMP
fish
rubidium
ouabain
Ouabain
Rubidium
kidneys
Seawater
seawater
Salmo trutta
Fresh Water
uptake mechanisms
Kidney
protein

Citer dette

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title = "Rapid modulation of Na+/K+-ATPase activity in osmoregulatory tissues of a salmonid fish",
abstract = "The effects of cyclic AMP on Na+/K+-ATPase activity were studied in the gill and kidney of the euryhaline brown trout Salmo trutta using two different experimental approaches. In the first series of experiments, in situ Na+/K+-ATPase activity was analyzed by measuring the ouabain-sensitive uptake of non-radioactive rubidium (Rb+) into gill cells and blocks of gill and kidney tissue. Rubidium uptake was linear for at least 30 min and was significantly inhibited by 1 mmol x l(-1) ouabain. Several agents presumed to increase the intracellular cyclic AMP concentration inhibited ouabain-sensitive Rb+ uptake in both gill (0.5 and 2 mmol x l(-1) dibutyryl-cyclic AMP, 1 mmol x l(-1) theophylline, 10 micromol x l(-1) forskolin and 10 micromol x l(-1 )isoproterenol) and kidney (10 micromol x l(-1) forskolin) tissue from freshwater-acclimated fish. In a separate series of experiments, ATP hydrolase activity was assayed in a permeabilised gill membrane preparation after incubation of tissue blocks with 10 micromol x l(-1 )forskolin. Forskolin elevated gill cyclic AMP levels 40-fold, inhibited maximal enzymatic Na+/K+-ATPase activity (Vmax) in gill tissue from both freshwater- and seawater-acclimated fish and reduced the apparent K+ affinity in the gills of seawater-acclimated fish, demonstrating that the effects are mediated through modifications of the enzyme itself. The protein phosphatase inhibitors okadaic acid and cyclosporin A did not affect forskolin-induced inhibition of Na+/K+-ATPase activity, indicating that forskolin-mediated modulation was stable for the duration of assay. We suggest that cyclic-AMP-mediated phosphorylation through protein kinases may underlie the rapid modulation of Na+/K+-ATPase activity in the osmoregulatory tissues of euryhaline teleosts.",
keywords = "Animals, Bucladesine, Cyclic AMP, Cyclosporine, Enzyme Inhibitors, Forskolin, Fresh Water, Gills, Kidney, Okadaic Acid, Ouabain, Phosphodiesterase Inhibitors, Rubidium Radioisotopes, Seawater, Sodium-Potassium-Exchanging ATPase, Theophylline, Trout",
author = "Tipsmark, {Christian K{\o}lb{\ae}k} and Steffen Madsen",
year = "2001",
month = "2",
day = "1",
language = "English",
volume = "204",
pages = "701--709",
journal = "BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY",
issn = "0022-0949",
publisher = "The/Company of Biologists Ltd.",
number = "Pt 4",

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Rapid modulation of Na+/K+-ATPase activity in osmoregulatory tissues of a salmonid fish. / Tipsmark, Christian Kølbæk; Madsen, Steffen.

I: Journal of Experimental Biology, Bind 204, Nr. Pt 4, 01.02.2001, s. 701-709.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Rapid modulation of Na+/K+-ATPase activity in osmoregulatory tissues of a salmonid fish

AU - Tipsmark, Christian Kølbæk

AU - Madsen, Steffen

PY - 2001/2/1

Y1 - 2001/2/1

N2 - The effects of cyclic AMP on Na+/K+-ATPase activity were studied in the gill and kidney of the euryhaline brown trout Salmo trutta using two different experimental approaches. In the first series of experiments, in situ Na+/K+-ATPase activity was analyzed by measuring the ouabain-sensitive uptake of non-radioactive rubidium (Rb+) into gill cells and blocks of gill and kidney tissue. Rubidium uptake was linear for at least 30 min and was significantly inhibited by 1 mmol x l(-1) ouabain. Several agents presumed to increase the intracellular cyclic AMP concentration inhibited ouabain-sensitive Rb+ uptake in both gill (0.5 and 2 mmol x l(-1) dibutyryl-cyclic AMP, 1 mmol x l(-1) theophylline, 10 micromol x l(-1) forskolin and 10 micromol x l(-1 )isoproterenol) and kidney (10 micromol x l(-1) forskolin) tissue from freshwater-acclimated fish. In a separate series of experiments, ATP hydrolase activity was assayed in a permeabilised gill membrane preparation after incubation of tissue blocks with 10 micromol x l(-1 )forskolin. Forskolin elevated gill cyclic AMP levels 40-fold, inhibited maximal enzymatic Na+/K+-ATPase activity (Vmax) in gill tissue from both freshwater- and seawater-acclimated fish and reduced the apparent K+ affinity in the gills of seawater-acclimated fish, demonstrating that the effects are mediated through modifications of the enzyme itself. The protein phosphatase inhibitors okadaic acid and cyclosporin A did not affect forskolin-induced inhibition of Na+/K+-ATPase activity, indicating that forskolin-mediated modulation was stable for the duration of assay. We suggest that cyclic-AMP-mediated phosphorylation through protein kinases may underlie the rapid modulation of Na+/K+-ATPase activity in the osmoregulatory tissues of euryhaline teleosts.

AB - The effects of cyclic AMP on Na+/K+-ATPase activity were studied in the gill and kidney of the euryhaline brown trout Salmo trutta using two different experimental approaches. In the first series of experiments, in situ Na+/K+-ATPase activity was analyzed by measuring the ouabain-sensitive uptake of non-radioactive rubidium (Rb+) into gill cells and blocks of gill and kidney tissue. Rubidium uptake was linear for at least 30 min and was significantly inhibited by 1 mmol x l(-1) ouabain. Several agents presumed to increase the intracellular cyclic AMP concentration inhibited ouabain-sensitive Rb+ uptake in both gill (0.5 and 2 mmol x l(-1) dibutyryl-cyclic AMP, 1 mmol x l(-1) theophylline, 10 micromol x l(-1) forskolin and 10 micromol x l(-1 )isoproterenol) and kidney (10 micromol x l(-1) forskolin) tissue from freshwater-acclimated fish. In a separate series of experiments, ATP hydrolase activity was assayed in a permeabilised gill membrane preparation after incubation of tissue blocks with 10 micromol x l(-1 )forskolin. Forskolin elevated gill cyclic AMP levels 40-fold, inhibited maximal enzymatic Na+/K+-ATPase activity (Vmax) in gill tissue from both freshwater- and seawater-acclimated fish and reduced the apparent K+ affinity in the gills of seawater-acclimated fish, demonstrating that the effects are mediated through modifications of the enzyme itself. The protein phosphatase inhibitors okadaic acid and cyclosporin A did not affect forskolin-induced inhibition of Na+/K+-ATPase activity, indicating that forskolin-mediated modulation was stable for the duration of assay. We suggest that cyclic-AMP-mediated phosphorylation through protein kinases may underlie the rapid modulation of Na+/K+-ATPase activity in the osmoregulatory tissues of euryhaline teleosts.

KW - Animals

KW - Bucladesine

KW - Cyclic AMP

KW - Cyclosporine

KW - Enzyme Inhibitors

KW - Forskolin

KW - Fresh Water

KW - Gills

KW - Kidney

KW - Okadaic Acid

KW - Ouabain

KW - Phosphodiesterase Inhibitors

KW - Rubidium Radioisotopes

KW - Seawater

KW - Sodium-Potassium-Exchanging ATPase

KW - Theophylline

KW - Trout

M3 - Journal article

VL - 204

SP - 701

EP - 709

JO - BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY

JF - BRITISH JOURNAL OF EXPERIMENTAL BIOLOGY

SN - 0022-0949

IS - Pt 4

ER -