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Regulation of apical H+-ATPase activity and intestinal HCO3− secretion in marine fish osmoregulation

Regulation of apical H+-ATPase activity and intestinal HCO3− secretion in marine fish osmoregulation Abstract The absorption of Cl − and water from ingested seawater in the marine fish intestine is accomplished partly through Cl − /HCO 3 − exchange. Recently, a H + pump (vacuolar-type H + -ATPase) was found to secrete acid into the intestinal lumen, and it may serve to titrate luminal HCO 3 − and facilitate further Cl − /HCO 3 − exchange, especially in the posterior intestine, where adverse concentration gradients could limit Cl − /HCO 3 − exchange. The H + pump is expressed in all intestinal segments and in gill tissue of gulf toadfish ( Opsanus beta ) maintained in natural seawater. After acute transfer of toadfish to 60 ppt salinity, H + pump expression increased 20-fold in the posterior intestine. In agreement with these observations was a fourfold-increased H + -ATPase activity in the posterior intestine of animals acclimated to 60 ppt salinity. Interestingly, Na + -K + -ATPase activity was elevated in the anterior intestine and gill, but not in the posterior intestine. Apical acid secretion by isolated intestinal tissue mounted in Ussing chambers fitted with pH-stat titration systems increased after acclimation to hypersalinity in the anterior and posterior intestine, titrating >20% of secreted bicarbonate. In addition, net base secretion increased in hypersalinity-acclimated fish and was ∼70% dependent on serosal HCO 3 − . Protein localization by immunohistochemistry confirmed the presence of the vacuolar-type H + -ATPase in the apical region of intestinal enterocytes. These results show that the H + pump, especially in the posterior intestine, plays an important role in hypersaline osmoregulation and that it likely has significant effects on HCO 3 − accumulation in the intestinal lumen and, therefore, the continued absorption of Cl − and water. water absorption posterior intestine pH-stat titration salinity ion transport Copyright © 2011 the American Physiological Society « Previous | Next Article » Table of Contents This Article Published online before print August 2011 , doi: 10.​1152/​ajpregu.​00059.​2011 AJP - Regu Physiol December 2011 vol. 301 no. 6 R1682-R1691 » Abstract Free Full Text Free to you Full Text (PDF) Free to you All Versions of this Article: ajpregu.00059.2011v1 301/6/R1682 most recent Classifications Research Services Email this article to a friend Alert me when this article is cited Alert me if a correction is posted Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Download to citation manager Citing Articles Load citing article information Citing articles via Web of Science Google Scholar Articles by Guffey, S. Articles by Grosell, M. PubMed PubMed citation Articles by Guffey, S. Articles by Grosell, M. Related Content Load related web page information Current Issue December 2011, 301 (6) Alert me to new issues of AJP - Regu Physiol About the Journal Information for Authors Submit a Manuscript Ethical Policies AuthorChoice PubMed Central Policy Reprints and Permissions Advertising Press Copyright © 2011 the American Physiological Society Print ISSN: 0363-6119 Online ISSN: 1522-1490 var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); var pageTracker = _gat._getTracker("UA-2924550-1"); pageTracker._trackPageview(); http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Regulatory, Integrative and Comparative Physiology The American Physiological Society

Regulation of apical H+-ATPase activity and intestinal HCO3− secretion in marine fish osmoregulation

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Publisher
The American Physiological Society
Copyright
Copyright © 2011 the American Physiological Society
ISSN
0363-6119
eISSN
1522-1490
DOI
10.1152/ajpregu.00059.2011
pmid
21865541
Publisher site
See Article on Publisher Site

Abstract

Abstract The absorption of Cl − and water from ingested seawater in the marine fish intestine is accomplished partly through Cl − /HCO 3 − exchange. Recently, a H + pump (vacuolar-type H + -ATPase) was found to secrete acid into the intestinal lumen, and it may serve to titrate luminal HCO 3 − and facilitate further Cl − /HCO 3 − exchange, especially in the posterior intestine, where adverse concentration gradients could limit Cl − /HCO 3 − exchange. The H + pump is expressed in all intestinal segments and in gill tissue of gulf toadfish ( Opsanus beta ) maintained in natural seawater. After acute transfer of toadfish to 60 ppt salinity, H + pump expression increased 20-fold in the posterior intestine. In agreement with these observations was a fourfold-increased H + -ATPase activity in the posterior intestine of animals acclimated to 60 ppt salinity. Interestingly, Na + -K + -ATPase activity was elevated in the anterior intestine and gill, but not in the posterior intestine. Apical acid secretion by isolated intestinal tissue mounted in Ussing chambers fitted with pH-stat titration systems increased after acclimation to hypersalinity in the anterior and posterior intestine, titrating >20% of secreted bicarbonate. In addition, net base secretion increased in hypersalinity-acclimated fish and was ∼70% dependent on serosal HCO 3 − . Protein localization by immunohistochemistry confirmed the presence of the vacuolar-type H + -ATPase in the apical region of intestinal enterocytes. These results show that the H + pump, especially in the posterior intestine, plays an important role in hypersaline osmoregulation and that it likely has significant effects on HCO 3 − accumulation in the intestinal lumen and, therefore, the continued absorption of Cl − and water. water absorption posterior intestine pH-stat titration salinity ion transport Copyright © 2011 the American Physiological Society « Previous | Next Article » Table of Contents This Article Published online before print August 2011 , doi: 10.​1152/​ajpregu.​00059.​2011 AJP - Regu Physiol December 2011 vol. 301 no. 6 R1682-R1691 » Abstract Free Full Text Free to you Full Text (PDF) Free to you All Versions of this Article: ajpregu.00059.2011v1 301/6/R1682 most recent Classifications Research Services Email this article to a friend Alert me when this article is cited Alert me if a correction is posted Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Download to citation manager Citing Articles Load citing article information Citing articles via Web of Science Google Scholar Articles by Guffey, S. Articles by Grosell, M. PubMed PubMed citation Articles by Guffey, S. Articles by Grosell, M. Related Content Load related web page information Current Issue December 2011, 301 (6) Alert me to new issues of AJP - Regu Physiol About the Journal Information for Authors Submit a Manuscript Ethical Policies AuthorChoice PubMed Central Policy Reprints and Permissions Advertising Press Copyright © 2011 the American Physiological Society Print ISSN: 0363-6119 Online ISSN: 1522-1490 var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); var pageTracker = _gat._getTracker("UA-2924550-1"); pageTracker._trackPageview();

Journal

AJP - Regulatory, Integrative and Comparative PhysiologyThe American Physiological Society

Published: Dec 1, 2011

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