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.
Skip Nav Destination
JOURNAL ARTICLE| 01 August 1999
NO2- uptake and HCO3- excretion in the intestine of the European flounder (Platichthys flesus)
Online Issn: 1477-9145
Print Issn: 0022-0949
© 1999 by Company of Biologists
J Exp Biol (1999) 202 (15): 2103–2110.
- Views Icon Views
- PDF LinkPDF
- Share Icon Share
- Search Site
M. Grosell, F.B. Jensen; NO2- uptake and HCO3- excretion in the intestine of the European flounder (Platichthys flesus). J Exp Biol 1 August 1999; 202 (15): 2103–2110. doi: https://doi.org/10.1242/jeb.202.15.2103
Download citation file: