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Physiol Biochem Zool. 2006 Nov-Dec;79(6):981-96. Epub 2006 Oct 5.

Chloride uptake and base secretion in freshwater fish: a transepithelial ion-transport metabolon?

Author information

1
Department of Biological Sciences, University of Alberta, Edmonton, Alberta T5G 2E9, Canada. martint@ualberta.ca

Abstract

Despite all the efforts and technological advances during the last few decades, the cellular mechanisms for branchial chloride uptake in freshwater (FW) fish are still unclear. Although a tight 1 : 1 link with HCO-3 secretion has been established, not much is known about the identity of the ion-transporting proteins involved or the energizing steps that allow for the inward transport of Cl- against the concentration gradient. We propose a new model for Cl- uptake in FW fish whereby the combined action of an apical anion exchanger, cytoplasmic carbonic anhydrase, and basolateral V-type H+ -ATPase creates a local [HCO-3] high enough to energize Cl- uptake. Our model is based on analyses of structure-function relationships, reinterpretation of previous results, and novel observations about gill cell subtypes and immunolocalization of the V-H+ -ATPase.

PMID:
17041864
DOI:
10.1086/507658
[Indexed for MEDLINE]

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