Intestinal bicarbonate secretion in marine teleost fish - Source of bicarbonate, pH sensitivity, and consequences for whole animal acid-base and calcium homeostasis

Rod W. Wilson, Martin Grosell

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

Whole animal studies using seawater European flounder (Platichthys flesus) revealed that increasing intestinal [Ca2+] to 20 mM stimulated net HCO3- base secretion by 57%, but this was effectively balanced by an increase in net acid secretion, likely from the gills, to maintain whole animal acid-base status. Higher Ca2+ concentrations (40 and 70 mM) in ambient seawater resulted in reduced plasma total CO 2. This indicates (1) imperfect acid-base compensation, and (2) that endogenous metabolic CO2 is insufficient to fuel intestinal HCO 3- secretion, under hyper-stimulated conditions. Bicarbonate secretion plays an important role in preventing calcium absorption by precipitating a large fraction of the imbibed calcium as CaCO3. Indeed, under high Ca2+ conditions (20 mM), up to 75% of the intestinal Ca2+ is precipitated as CaCO3 and then excreted. This is undoubtedly important in protecting the marine teleost kidney from the need for excessive calcium excretion and risk of renal stone formation. Using an in vitro pH-stat technique with the isolated intestinal epithelium, the replacement of serosal CO2 with a HEPES buffered saline had no effect on HCO3- secretion, indicating that the endogenous supply of HCO3- from CO2 hydration within epithelial cells is adequate for driving baseline secretion rates. Further, in vitro data demonstrated a stimulatory effect of low pH on intestinal HCO 3- secretion. Thus, both luminal Ca2+ and H+ can regulate HCO3- secretion but the precise mechanisms and their potential interaction are currently unresolved.

Original languageEnglish
Pages (from-to)163-174
Number of pages12
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1618
Issue number2
DOIs
StatePublished - Dec 30 2003

Fingerprint

Intestinal Secretions
Bicarbonates
Fish
Flounder
Fishes
Animals
Homeostasis
Seawater
Calcium
Acids
HEPES
Carbon Monoxide
Intestinal Mucosa
Hydration
Epithelial Cells
Kidney
Plasmas
In Vitro Techniques

Keywords

  • Acid-base balance
  • Calcium and magnesium homeostasis
  • Calcium carbonate precipitation
  • Chloride-bicarbonate exchange
  • Osmoregulation
  • Water absorption

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics

Cite this

@article{313a383f50384e40888e16347bf64836,
title = "Intestinal bicarbonate secretion in marine teleost fish - Source of bicarbonate, pH sensitivity, and consequences for whole animal acid-base and calcium homeostasis",
abstract = "Whole animal studies using seawater European flounder (Platichthys flesus) revealed that increasing intestinal [Ca2+] to 20 mM stimulated net HCO3- base secretion by 57{\%}, but this was effectively balanced by an increase in net acid secretion, likely from the gills, to maintain whole animal acid-base status. Higher Ca2+ concentrations (40 and 70 mM) in ambient seawater resulted in reduced plasma total CO 2. This indicates (1) imperfect acid-base compensation, and (2) that endogenous metabolic CO2 is insufficient to fuel intestinal HCO 3- secretion, under hyper-stimulated conditions. Bicarbonate secretion plays an important role in preventing calcium absorption by precipitating a large fraction of the imbibed calcium as CaCO3. Indeed, under high Ca2+ conditions (20 mM), up to 75{\%} of the intestinal Ca2+ is precipitated as CaCO3 and then excreted. This is undoubtedly important in protecting the marine teleost kidney from the need for excessive calcium excretion and risk of renal stone formation. Using an in vitro pH-stat technique with the isolated intestinal epithelium, the replacement of serosal CO2 with a HEPES buffered saline had no effect on HCO3- secretion, indicating that the endogenous supply of HCO3- from CO2 hydration within epithelial cells is adequate for driving baseline secretion rates. Further, in vitro data demonstrated a stimulatory effect of low pH on intestinal HCO 3- secretion. Thus, both luminal Ca2+ and H+ can regulate HCO3- secretion but the precise mechanisms and their potential interaction are currently unresolved.",
keywords = "Acid-base balance, Calcium and magnesium homeostasis, Calcium carbonate precipitation, Chloride-bicarbonate exchange, Osmoregulation, Water absorption",
author = "Wilson, {Rod W.} and Martin Grosell",
year = "2003",
month = "12",
day = "30",
doi = "10.1016/j.bbamem.2003.09.014",
language = "English",
volume = "1618",
pages = "163--174",
journal = "Biochimica et Biophysica Acta - Biomembranes",
issn = "0005-2736",
publisher = "Elsevier",
number = "2",

}

TY - JOUR

T1 - Intestinal bicarbonate secretion in marine teleost fish - Source of bicarbonate, pH sensitivity, and consequences for whole animal acid-base and calcium homeostasis

AU - Wilson, Rod W.

AU - Grosell, Martin

PY - 2003/12/30

Y1 - 2003/12/30

N2 - Whole animal studies using seawater European flounder (Platichthys flesus) revealed that increasing intestinal [Ca2+] to 20 mM stimulated net HCO3- base secretion by 57%, but this was effectively balanced by an increase in net acid secretion, likely from the gills, to maintain whole animal acid-base status. Higher Ca2+ concentrations (40 and 70 mM) in ambient seawater resulted in reduced plasma total CO 2. This indicates (1) imperfect acid-base compensation, and (2) that endogenous metabolic CO2 is insufficient to fuel intestinal HCO 3- secretion, under hyper-stimulated conditions. Bicarbonate secretion plays an important role in preventing calcium absorption by precipitating a large fraction of the imbibed calcium as CaCO3. Indeed, under high Ca2+ conditions (20 mM), up to 75% of the intestinal Ca2+ is precipitated as CaCO3 and then excreted. This is undoubtedly important in protecting the marine teleost kidney from the need for excessive calcium excretion and risk of renal stone formation. Using an in vitro pH-stat technique with the isolated intestinal epithelium, the replacement of serosal CO2 with a HEPES buffered saline had no effect on HCO3- secretion, indicating that the endogenous supply of HCO3- from CO2 hydration within epithelial cells is adequate for driving baseline secretion rates. Further, in vitro data demonstrated a stimulatory effect of low pH on intestinal HCO 3- secretion. Thus, both luminal Ca2+ and H+ can regulate HCO3- secretion but the precise mechanisms and their potential interaction are currently unresolved.

AB - Whole animal studies using seawater European flounder (Platichthys flesus) revealed that increasing intestinal [Ca2+] to 20 mM stimulated net HCO3- base secretion by 57%, but this was effectively balanced by an increase in net acid secretion, likely from the gills, to maintain whole animal acid-base status. Higher Ca2+ concentrations (40 and 70 mM) in ambient seawater resulted in reduced plasma total CO 2. This indicates (1) imperfect acid-base compensation, and (2) that endogenous metabolic CO2 is insufficient to fuel intestinal HCO 3- secretion, under hyper-stimulated conditions. Bicarbonate secretion plays an important role in preventing calcium absorption by precipitating a large fraction of the imbibed calcium as CaCO3. Indeed, under high Ca2+ conditions (20 mM), up to 75% of the intestinal Ca2+ is precipitated as CaCO3 and then excreted. This is undoubtedly important in protecting the marine teleost kidney from the need for excessive calcium excretion and risk of renal stone formation. Using an in vitro pH-stat technique with the isolated intestinal epithelium, the replacement of serosal CO2 with a HEPES buffered saline had no effect on HCO3- secretion, indicating that the endogenous supply of HCO3- from CO2 hydration within epithelial cells is adequate for driving baseline secretion rates. Further, in vitro data demonstrated a stimulatory effect of low pH on intestinal HCO 3- secretion. Thus, both luminal Ca2+ and H+ can regulate HCO3- secretion but the precise mechanisms and their potential interaction are currently unresolved.

KW - Acid-base balance

KW - Calcium and magnesium homeostasis

KW - Calcium carbonate precipitation

KW - Chloride-bicarbonate exchange

KW - Osmoregulation

KW - Water absorption

UR - http://www.scopus.com/inward/record.url?scp=0346654144&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0346654144&partnerID=8YFLogxK

U2 - 10.1016/j.bbamem.2003.09.014

DO - 10.1016/j.bbamem.2003.09.014

M3 - Article

C2 - 14729153

AN - SCOPUS:0346654144

VL - 1618

SP - 163

EP - 174

JO - Biochimica et Biophysica Acta - Biomembranes

JF - Biochimica et Biophysica Acta - Biomembranes

SN - 0005-2736

IS - 2

ER -