Mechanisms of dietary Cu uptake in freshwater rainbow trout

Evidence for Na-assisted Cu transport and a specific metal carrier in the intestine

Sunita Rao Nadella, Martin Grosell, Chris M. Wood

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Copper (Cu) is both a vital nutrient and a potent toxicant. The objective of this study was to analyze the mechanistic nature of intestinal Cu transport in rainbow trout using radiolabeled Cu (64Cu) and an in vitro gut sac technique. Reduction of mucosal NaCl levels inhibited Cu transport while increase caused stimulation; Na2SO4 had an identical effect, implicating Na+ rather than the anion. These responses were unrelated to solvent drag, osmotic pressure or changes in transepithelial potential. The presence of elevated luminal Ag stimulated Cu and Na+ uptake. Phenamil caused a partial inhibition of both Cu and Na+ uptake while hypercapnia stimulated Na+ and Cu transport. Cu uptake was sensitive to luminal pH and inhibited by a tenfold excess of Fe and Zn. These factors had no effect on Na+ uptake. On the basis of these results we propose a novel Na+-assisted mechanism of Cu uptake wherein the Na+ gradient stimulates an increase in the H+ concentration of the brushborder creating a suitable microenvironment for the effective transport of Cu via either DMT1 or Ctr1.

Original languageEnglish
Pages (from-to)433-446
Number of pages14
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume177
Issue number4
DOIs
StatePublished - May 1 2007

Fingerprint

Hypercapnia
Oncorhynchus mykiss
Osmotic Pressure
Fresh Water
Nutrients
rainbow
Intestines
Anions
Drag
Copper
intestines
Metals
metals
uptake mechanisms
Food
metal
drag
anion
copper
nutrient

Keywords

  • Ctr1
  • DMT1
  • Hypercapnia
  • NHE
  • pH

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Environmental Science(all)
  • Physiology
  • Physiology (medical)

Cite this

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abstract = "Copper (Cu) is both a vital nutrient and a potent toxicant. The objective of this study was to analyze the mechanistic nature of intestinal Cu transport in rainbow trout using radiolabeled Cu (64Cu) and an in vitro gut sac technique. Reduction of mucosal NaCl levels inhibited Cu transport while increase caused stimulation; Na2SO4 had an identical effect, implicating Na+ rather than the anion. These responses were unrelated to solvent drag, osmotic pressure or changes in transepithelial potential. The presence of elevated luminal Ag stimulated Cu and Na+ uptake. Phenamil caused a partial inhibition of both Cu and Na+ uptake while hypercapnia stimulated Na+ and Cu transport. Cu uptake was sensitive to luminal pH and inhibited by a tenfold excess of Fe and Zn. These factors had no effect on Na+ uptake. On the basis of these results we propose a novel Na+-assisted mechanism of Cu uptake wherein the Na+ gradient stimulates an increase in the H+ concentration of the brushborder creating a suitable microenvironment for the effective transport of Cu via either DMT1 or Ctr1.",
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AU - Wood, Chris M.

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N2 - Copper (Cu) is both a vital nutrient and a potent toxicant. The objective of this study was to analyze the mechanistic nature of intestinal Cu transport in rainbow trout using radiolabeled Cu (64Cu) and an in vitro gut sac technique. Reduction of mucosal NaCl levels inhibited Cu transport while increase caused stimulation; Na2SO4 had an identical effect, implicating Na+ rather than the anion. These responses were unrelated to solvent drag, osmotic pressure or changes in transepithelial potential. The presence of elevated luminal Ag stimulated Cu and Na+ uptake. Phenamil caused a partial inhibition of both Cu and Na+ uptake while hypercapnia stimulated Na+ and Cu transport. Cu uptake was sensitive to luminal pH and inhibited by a tenfold excess of Fe and Zn. These factors had no effect on Na+ uptake. On the basis of these results we propose a novel Na+-assisted mechanism of Cu uptake wherein the Na+ gradient stimulates an increase in the H+ concentration of the brushborder creating a suitable microenvironment for the effective transport of Cu via either DMT1 or Ctr1.

AB - Copper (Cu) is both a vital nutrient and a potent toxicant. The objective of this study was to analyze the mechanistic nature of intestinal Cu transport in rainbow trout using radiolabeled Cu (64Cu) and an in vitro gut sac technique. Reduction of mucosal NaCl levels inhibited Cu transport while increase caused stimulation; Na2SO4 had an identical effect, implicating Na+ rather than the anion. These responses were unrelated to solvent drag, osmotic pressure or changes in transepithelial potential. The presence of elevated luminal Ag stimulated Cu and Na+ uptake. Phenamil caused a partial inhibition of both Cu and Na+ uptake while hypercapnia stimulated Na+ and Cu transport. Cu uptake was sensitive to luminal pH and inhibited by a tenfold excess of Fe and Zn. These factors had no effect on Na+ uptake. On the basis of these results we propose a novel Na+-assisted mechanism of Cu uptake wherein the Na+ gradient stimulates an increase in the H+ concentration of the brushborder creating a suitable microenvironment for the effective transport of Cu via either DMT1 or Ctr1.

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