Cargando…

Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine

Intestinal water absorption is greatly enhanced in salmonids upon acclimation from freshwater (FW) to seawater (SW); however, the molecular mechanism for water transport is unknown. We conducted a pharmacological characterization of water absorption in the rainbow trout intestine along with an inves...

Descripción completa

Detalles Bibliográficos
Autores principales: Madsen, Steffen S., Olesen, Jesper H., Bedal, Konstanze, Engelund, Morten Buch, Velasco-Santamaría, Yohana M., Tipsmark, Christian K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Research Foundation 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3171111/
https://www.ncbi.nlm.nih.gov/pubmed/21941512
http://dx.doi.org/10.3389/fphys.2011.00056
_version_ 1782211717251465216
author Madsen, Steffen S.
Olesen, Jesper H.
Bedal, Konstanze
Engelund, Morten Buch
Velasco-Santamaría, Yohana M.
Tipsmark, Christian K.
author_facet Madsen, Steffen S.
Olesen, Jesper H.
Bedal, Konstanze
Engelund, Morten Buch
Velasco-Santamaría, Yohana M.
Tipsmark, Christian K.
author_sort Madsen, Steffen S.
collection PubMed
description Intestinal water absorption is greatly enhanced in salmonids upon acclimation from freshwater (FW) to seawater (SW); however, the molecular mechanism for water transport is unknown. We conducted a pharmacological characterization of water absorption in the rainbow trout intestine along with an investigation of the distribution and cellular localization of three aquaporins (Aqp1aa, -1ab, and -8ab) in pyloric caeca, middle (M), and posterior (P) intestine of the Atlantic salmon. In vitro iso-osmotic water absorption (J(v)) was higher in SW than FW-trout and was inhibited by (mmol L(−1)): 0.1 KCN (41%), 0.1 ouabain (72%), and 0.1 bumetanide (82%) suggesting that active transport, Na(+), K(+)-ATPase and Na(+), K(+), 2Cl(−)-co-transport are involved in establishing the driving gradient for water transport. J(v) was also inhibited by 1 mmol L(−1) HgCl(2), serosally (23% in M and 44% in P), mucosally (27% in M), or both (61% in M and 58% in P), suggesting involvement of both apical and basolateral aquaporins in water transport. The inhibition was antagonized by 5 mmol L(−1) mercaptoethanol. By comparison, 10 mmol L(−1) mucosal tetraethylammonium, an inhibitor of certain aquaporins, inhibited J(v) by 20%. In the presence of glucose, mucosal addition of phloridzin inhibited water transport by 20%, suggesting that water transport is partially linked to the Na(+)-glucose co-transporter. Using polyclonal antibodies against salmon Aqp1aa, -1ab, and -8ab, we detected Aqp1aa, and -1ab immunoreactivity in the brush border and sub-apical region of enterocytes in all intestinal segments. The Aqp8ab antibody showed a particularly strong immunoreaction in the brush border and sub-apical region of enterocytes throughout the intestine and also stained lateral membranes and peri-nuclear regions though at lower intensity. The present localization of three aquaporins in both apical and lateral membranes of salmonid enterocytes facilitates a model for transcellular water transport in the intestine of SW-acclimated salmonids.
format Online
Article
Text
id pubmed-3171111
institution National Center for Biotechnology Information
language English
publishDate 2011
publisher Frontiers Research Foundation
record_format MEDLINE/PubMed
spelling pubmed-31711112011-09-22 Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine Madsen, Steffen S. Olesen, Jesper H. Bedal, Konstanze Engelund, Morten Buch Velasco-Santamaría, Yohana M. Tipsmark, Christian K. Front Physiol Physiology Intestinal water absorption is greatly enhanced in salmonids upon acclimation from freshwater (FW) to seawater (SW); however, the molecular mechanism for water transport is unknown. We conducted a pharmacological characterization of water absorption in the rainbow trout intestine along with an investigation of the distribution and cellular localization of three aquaporins (Aqp1aa, -1ab, and -8ab) in pyloric caeca, middle (M), and posterior (P) intestine of the Atlantic salmon. In vitro iso-osmotic water absorption (J(v)) was higher in SW than FW-trout and was inhibited by (mmol L(−1)): 0.1 KCN (41%), 0.1 ouabain (72%), and 0.1 bumetanide (82%) suggesting that active transport, Na(+), K(+)-ATPase and Na(+), K(+), 2Cl(−)-co-transport are involved in establishing the driving gradient for water transport. J(v) was also inhibited by 1 mmol L(−1) HgCl(2), serosally (23% in M and 44% in P), mucosally (27% in M), or both (61% in M and 58% in P), suggesting involvement of both apical and basolateral aquaporins in water transport. The inhibition was antagonized by 5 mmol L(−1) mercaptoethanol. By comparison, 10 mmol L(−1) mucosal tetraethylammonium, an inhibitor of certain aquaporins, inhibited J(v) by 20%. In the presence of glucose, mucosal addition of phloridzin inhibited water transport by 20%, suggesting that water transport is partially linked to the Na(+)-glucose co-transporter. Using polyclonal antibodies against salmon Aqp1aa, -1ab, and -8ab, we detected Aqp1aa, and -1ab immunoreactivity in the brush border and sub-apical region of enterocytes in all intestinal segments. The Aqp8ab antibody showed a particularly strong immunoreaction in the brush border and sub-apical region of enterocytes throughout the intestine and also stained lateral membranes and peri-nuclear regions though at lower intensity. The present localization of three aquaporins in both apical and lateral membranes of salmonid enterocytes facilitates a model for transcellular water transport in the intestine of SW-acclimated salmonids. Frontiers Research Foundation 2011-09-07 /pmc/articles/PMC3171111/ /pubmed/21941512 http://dx.doi.org/10.3389/fphys.2011.00056 Text en Copyright © 2011 Madsen, Olesen, Bedal, Engelund, Velasco-Santamaría and Tipsmark. http://www.frontiersin.org/licenseagreement This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and other Frontiers conditions are complied with.
spellingShingle Physiology
Madsen, Steffen S.
Olesen, Jesper H.
Bedal, Konstanze
Engelund, Morten Buch
Velasco-Santamaría, Yohana M.
Tipsmark, Christian K.
Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine
title Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine
title_full Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine
title_fullStr Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine
title_full_unstemmed Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine
title_short Functional Characterization of Water Transport and Cellular Localization of Three Aquaporin Paralogs in the Salmonid Intestine
title_sort functional characterization of water transport and cellular localization of three aquaporin paralogs in the salmonid intestine
topic Physiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3171111/
https://www.ncbi.nlm.nih.gov/pubmed/21941512
http://dx.doi.org/10.3389/fphys.2011.00056
work_keys_str_mv AT madsensteffens functionalcharacterizationofwatertransportandcellularlocalizationofthreeaquaporinparalogsinthesalmonidintestine
AT olesenjesperh functionalcharacterizationofwatertransportandcellularlocalizationofthreeaquaporinparalogsinthesalmonidintestine
AT bedalkonstanze functionalcharacterizationofwatertransportandcellularlocalizationofthreeaquaporinparalogsinthesalmonidintestine
AT engelundmortenbuch functionalcharacterizationofwatertransportandcellularlocalizationofthreeaquaporinparalogsinthesalmonidintestine
AT velascosantamariayohanam functionalcharacterizationofwatertransportandcellularlocalizationofthreeaquaporinparalogsinthesalmonidintestine
AT tipsmarkchristiank functionalcharacterizationofwatertransportandcellularlocalizationofthreeaquaporinparalogsinthesalmonidintestine