title: A role for sodium-chloride cotransporters in the rapid regulation of ion uptake following acute environmental acidosis: new insights from the zebrafish model.
abstract: The effects of acute exposure to acidic water on Na+and Cl-homeostasis, and the mechanisms underlying their compensatory regulation, were investigated in the larval zebrafish Danio rerio Exposure to acidic water (pH 4.0; control pH 7.6) for 2 h significantly reduced Na+uptake and whole body Na+content. Nevertheless, the capacity for Na+uptake was substantially increased in fish preexposed to acidic water but measured in control water. Based on the accumulation of the Na+-selective dye, Sodium Green, two ionocyte subtypes exhibited intracellular Na+enrichment after preexposure to acidic water: H+-ATPase rich (HR) cells, which coexpress the Na+/H+exchanger isoform 3b (NHE3b), and a non-HR cell population. In fish experiencing Na+-Cl-cotransporter (NCC) knockdown, we observed no Sodium Green accumulation in the latter cell type, suggesting the non-HR cells were NCC cells. Elimination of NHE3b-expressing HR cells did not prevent the increased Na+uptake following acid exposure. On the other hand, the increased Na+uptake was abolished when the acidic water was enriched with Na+and Cl-, but not with Na+only, indicating that the elevated Na+uptake after acid exposure was associated with the compensatory regulation of Cl-Further examinations demonstrated that acute acid exposure also reduced whole body Cl-levels and increased the capacity for Cl-uptake. Moreover, knockdown of NCC prevented the increased uptake of both Na+and Cl-after exposure to acidic water. Together, the results of the present study revealed a novel role of NCC in the compensatory regulation of Na+and Cl-uptake following acute acidosis.
authors: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada; and rwmkwong@yorku.ca.|Department of Biology, York University, Toronto, Ontario, Canada.
authors: Raymond W M
authors: RW
authors: Kwong
authors: Department of Biology, University of Ottawa, Ottawa, Ontario, Canada; and.
authors: Steve F
authors: SF
authors: Perry
mesh_terms: D000138:Acidosis / Q000378:metabolism*; D000818:Animals; D002712:Chlorides / Q000378:metabolism; D007477:Ions / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D049992:Sodium Chloride Symporters / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D002712:Chlorides; D007477:Ions; D020033:Protein Isoforms; D049992:Sodium Chloride Symporters; D017923:Sodium-Hydrogen Exchangers; D029961:Zebrafish Proteins; D012964:Sodium; D006180:Proton-Translocating ATPases
keywords: Na+-Cl− cotransporter; Na+/H+ exchanger; acidosis; chloride; ionocyte; sodium; zebrafish