PUBLICATION
A novel K+ -dependent Na+ uptake mechanism during low pH exposure in adult zebrafish (Danio rerio): New tricks for old dogma
- Authors
- Clifford, A.M., Tresguerres, M., Goss, G.G., Wood, C.M.
- ID
- ZDB-PUB-220106-3
- Date
- 2022
- Source
- Acta physiologica (Oxford, England) 234(3): e13777 (Journal)
- Registered Authors
- Goss, Greg
- Keywords
- Ionoregulation, Na+-Cl- cotransporter, Na+/Ca2+-K+ exchanger, Na+/H+ exchanger, Sodium uptake, low pH
- MeSH Terms
-
- Animals
- Hydrogen-Ion Concentration
- Ions
- Sodium/metabolism
- Sodium-Hydrogen Exchangers/genetics
- Water
- Zebrafish*/metabolism
- Zebrafish Proteins*/genetics
- Zebrafish Proteins*/metabolism
- PubMed
- 34985194 Full text @ Acta Physiol. (Oxf).
Citation
Clifford, A.M., Tresguerres, M., Goss, G.G., Wood, C.M. (2022) A novel K+ -dependent Na+ uptake mechanism during low pH exposure in adult zebrafish (Danio rerio): New tricks for old dogma. Acta physiologica (Oxford, England). 234(3):e13777.
Abstract
Aim To determine whether Na+ uptake in adult zebrafish (Danio rerio) exposed to acidic water adheres to traditional models reliant on Na+ /H+ Exchangers (NHEs), Na+ channels, and Na+ /Cl- co-transporters (NCCs), or if it occurs through a novel mechanism.
Methods Zebrafish were exposed to control (pH 8.0) or acidic (pH 4.0) water for 0-12h during which 22 Na+ uptake (JNain ), ammonia excretion, net acidic equivalent flux, and net K+ flux (JKnet ) were measured. The involvement of NHEs, Na+ channels, NCCs, K+ -channels and K+ -dependent Na+ /Ca2+ exchanger (NCKXs) was evaluated by exposure to Cl- -free or elevated [K+ ] water, or to pharmacological inhibitors. The presence of NCKXs in gill was examined using RT-PCR.
Results JNain was strongly attenuated by acid exposure, but gradually recovered to control rates. The systematic elimination of each of the traditional models led us to consider K+ as a counter substrate for Na+ uptake during acid-exposure. Indeed, elevated environmental [K+ ] inhibited JNain during acid-exposure in a concentration-dependent manner, with near-complete inhibition at 10 mM. Moreover, JKnet increased ~4-fold during 8-10h acid-exposure which correlated with JNain in 1:1 fashion, and both JNain and JKnet were sensitive to tetraethylammonium (TEA) during acid exposure. Zebrafish gills expressed mRNA coding for six NCKX isoforms.
Conclusions During acid-exposure, zebrafish engage a novel Na+ uptake mechanism that utilizes the outwardly directed K+ gradient as a counter-substrate for Na+ and is sensitive to TEA. NKCXs are promising candidates to mediate this K+ -dependent Na+ uptake, opening new research avenues about Na+ uptake in zebrafish and other acid-tolerant aquatic species.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping