Assessing the role of the acid-sensing ion channel ASIC4b in sodium uptake by larval zebrafish.
Comp Biochem Physiol A Mol Integr Physiol
; 226: 1-10, 2018 12.
Article
em En
| MEDLINE
| ID: mdl-29913320
Na+ uptake in larval zebrafish (Danio rerio) is coordinated by three mechanisms: Na+/H+-exchanger 3b (NHE3b) expressed in H+-ATPase-rich (HR) cells, an unidentified Na+ channel coupled to electrogenic H+-ATPase expressed in HR cells, and Na+-Cl--cotransporter (NCC) expressed in NCC cells. Recently, acid-sensing ion channels (ASICs) were proposed to be the putative Na+ channel involved in H+-ATPase-mediated Na+ uptake in adult zebrafish and rainbow trout. In the present study, we hypothesized that ASICs also play this role in Na+ uptake in larval zebrafish. In support of this hypothesis, immunohistochemical analyses revealed that ASIC4b was expressed in HR cells on the yolk sac skin at 4â¯days post-fertilization (dpf). However, neither treatment with the ASIC-specific blocker 4,6-diamidino-2-phenylindole (DAPI) nor morpholino knockdown of ASIC4b reduced Na+ uptake in circumneutral conditions at 4 dpf. However, because ASIC4b knockdown led to significant increases in the mRNA expression of nhe3b and ncc and a significant increase in HR cell density, it is possible that Na+ influx was sustained by increased participation of non-ASIC4b pathways. Moreover, when fish were reared in acidic water (pHâ¯=â¯4), ASIC4b knockdown led to a stimulation of Na+ uptake at 3 and 4 dpf, results which also were inconsistent with an essential role for ASIC-mediated Na+ uptake, even under conditions known to constrain Na+ uptake via NHE3b. Thus, while ASIC4b clearly is expressed in HR cells, the current functional experiments cannot confirm its involvement in Na+ uptake in larval zebrafish.
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01-internacional
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MEDLINE
Assunto principal:
Sódio
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Peixe-Zebra
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Proteínas de Peixe-Zebra
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Canais Iônicos Sensíveis a Ácido
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Larva
Limite:
Animals
Idioma:
En
Revista:
Comp Biochem Physiol A Mol Integr Physiol
Ano de publicação:
2018
Tipo de documento:
Article