NO2- uptake and HCO3- excretion in the intestine of the European flounder (Platichthys flesus)

M. Grosell, F. B. Jensen

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85 Scopus citations


Ion transport across isolated intestinal segments from the European flounder (Platichthys flesus) was studied with the primary aim of evaluating the mechanisms of nitrite (NO2-) uptake and HCO3- excretion. A double-radiolabelling technique was applied to monitor unidirectional Cl- and Na+ influx. Furthermore, net fluxes of NO2-, HCO3-, Cl-, Na+ and water were recorded. NO2- uptake was inhibited by mucosal application of bumetanide (10-4 mol l-1) but not DIDS (10-3 mol l-1), suggesting that NO2- is transported across the intestine via the Na+/K+/2Cl- cotransporter rather than via a Cl-/HCO3-exchanger. In addition to transport via the Na+/K+/2Cl- cotransporter, NO2- uptake may also occur through the Na+/Cl- cotransporter and by conductive transport. NO2- and Cl- influx rates seemed to reflect their mucosal concentrations, and NO2- did not influence unidirectional influx or net flux of Cl-. HCO3- efflux was significantly reduced in the presence of 10-3 mol l-1 DIDS in the mucosal solution. This may indicate the presence of an apical Cl-/HCO3- exchanger in the intestinal epithelium, which would not comply with the current model of HCO3- excretion in the intestine of marine teleost fish. An alternative model of HCO3- excretion across the intestinal epithelium is proposed.

Original languageEnglish (US)
Pages (from-to)2103-2110
Number of pages8
JournalJournal of Experimental Biology
Issue number15
StatePublished - Aug 1 1999
Externally publishedYes


  • Base excretion
  • Bumetanide
  • Cl/HCO exchange
  • DIDS
  • Flounder
  • Ion transport
  • Marine teleost
  • Na/K/2Cl cotransport
  • Nitrite
  • NO
  • Platichthys flesus

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Agricultural and Biological Sciences (miscellaneous)


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