Document Detail

Ammonia excretion by the skin of zebrafish (Danio rerio) larvae.
MedLine Citation:
PMID:  18815227     Owner:  NLM     Status:  MEDLINE    
The mechanism of ammonia excretion in freshwater teleosts is not well understood. In this study, scanning ion-selective electrode technique was applied to measure H(+) and NH(4)(+) fluxes in specific cells on the skin of zebrafish larvae. NH(4)(+) extrusion was relatively high in H(+) pump-rich cells, which were identified as the H(+)-secreting ionocyte in zebrafish. Minor NH(4)(+) extrusion was also detected in keratinocytes and other types of ionocytes in larval skin. NH(4)(+) extrusion from the skin was tightly linked to acid secretion. Increases in the external pH and buffer concentration (5 mM MOPS) diminished H(+) and NH(4)(+) gradients at the larval surface. Moreover, coupled decreases in NH(4)(+) and H(+) extrusion were found in larvae treated with an H(+)-pump inhibitor (bafilomycin A1) or H(+)-pump gene (atp6v1a) knockdown. Knockdown of Rhcg1 with morpholino-oligonucleotides also decreased NH(4)(+) excretion. This study demonstrates ammonia excretion in epithelial cells of larval skin through an acid-trapping mechanism, and it provides direct evidence for the involvement of the H(+) pump and an Rh glycoprotein (Rhcg1) in ammonia excretion.
Tin-Han Shih; Jiun-Lin Horng; Pung-Pung Hwang; Li-Yih Lin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-09-24
Journal Detail:
Title:  American journal of physiology. Cell physiology     Volume:  295     ISSN:  0363-6143     ISO Abbreviation:  Am. J. Physiol., Cell Physiol.     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-12-08     Completed Date:  2009-02-20     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100901225     Medline TA:  Am J Physiol Cell Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  C1625-32     Citation Subset:  IM    
Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan, Republic of China.
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MeSH Terms
Ammonia / metabolism*
Cation Transport Proteins / metabolism
H(+)-K(+)-Exchanging ATPase / metabolism
Ion-Selective Electrodes
Proton Pumps / metabolism
Skin / metabolism*
Zebrafish / physiology*
Zebrafish Proteins / metabolism
Reg. No./Substance:
0/Cation Transport Proteins; 0/Proton Pumps; 0/Rhcg1 protein, zebrafish; 0/Zebrafish Proteins; 7664-41-7/Ammonia; EC ATPase

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