HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 288/4/R936    most recent 00684.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Grosell, M. Articles by Jensen, F. B. Search for Related Content PubMed PubMed Citation Articles by Grosell, M. Articles by Jensen, F. B.

WATER AND ELECTROLYTE HOMEOSTASIS

Bicarbonate secretion plays a role in chloride and water absorption of the European flounder intestine

¹RSMAS, University of Miami, Miami, Florida; ²McMaster University, Hamilton, Ontario, Canada; ³Exeter University, Exeter; ⁴Kings College, London, United Kingdom; and ⁵University of Southern Denmark, Odense, Denmark

Submitted 1 December 2003 ; accepted in final form 1 December 2004

Experiments performed on isolated intestinal segments from the marine teleost fish, the European flounder (Platichthys flesus), revealed that the intestinal epithelium is capable of secondary active HCO₃^– secretion in the order of 0.2–0.3 µmol·cm^–2·h^–1 against an apparent electrochemical gradient. The HCO₃^– secretion occurs via anion exchange, is dependent on mucosal Cl^–, results in very high mucosal HCO₃^– concentrations, and contributes significantly to Cl^– and fluid absorption. This present study was conducted under in vivo-like conditions, with mucosal saline resembling intestinal fluids in vivo. These conditions result in a transepithelial potential of –16.2 mV (serosal side negative), which is very different from the –2.2 mV observed under symmetrical conditions. Under these conditions, we found a significant part of the HCO₃^– secretion is fueled by endogenous epithelial CO₂ hydration mediated by carbonic anhydrase because acetazolamide (10^–4 M) was found to inhibit HCO₃^– secretion and removal of serosal CO₂ was found not to influence HCO₃^– secretion. Reversal of the epithelial electrochemical gradient for Cl^– (removal of serosal Cl^–) and elevation of serosal HCO₃^– resulted in enhanced HCO₃^– secretion and enhanced Cl^– and fluid absorption. Cl^– absorption via an anion exchange system appears to partly drive fluid absorption across the intestine in the absence of net Na⁺ absorption.

HCO₃^– secretion; chloride absorption; carbonic anhydrase; osmoregulation; marine teleost

This article has been cited by other articles:

				G. R. Scott, D. W. Baker, P. M. Schulte, and C. M. Wood Physiological and molecular mechanisms of osmoregulatory plasticity in killifish after seawater transfer J. Exp. Biol., August 1, 2008; 211(15): 2450 - 2459. [Abstract] [Full Text] [PDF]

				Y. Kurita, T. Nakada, A. Kato, H. Doi, A. C. Mistry, M.-H. Chang, M. F. Romero, and S. Hirose Identification of intestinal bicarbonate transporters involved in formation of carbonate precipitates to stimulate water absorption in marine teleost fish Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2008; 294(4): R1402 - R1412. [Abstract] [Full Text] [PDF]

				M. Grosell, K. M. Gilmour, and S. F. Perry Intestinal carbonic anhydrase, bicarbonate, and proton carriers play a role in the acclimation of rainbow trout to seawater Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2007; 293(5): R2099 - R2111. [Abstract] [Full Text] [PDF]

				C. Bucking and C. M. Wood Gastrointestinal processing of Na+, Cl-, and K+ during digestion: implications for homeostatic balance in freshwater rainbow trout Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2006; 291(6): R1764 - R1772. [Abstract] [Full Text] [PDF]

				M. Grosell and J. Genz Ouabain-sensitive bicarbonate secretion and acid absorption by the marine teleost fish intestine play a role in osmoregulation Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2006; 291(4): R1145 - R1156. [Abstract] [Full Text] [PDF]