A mechanism for branchial acid excretion in marine fish

Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts

J. B. Claiborne, C. R. Blackston, K. P. Choe, D. C. Dawson, S. P. Harris, L. A. Mackenzie, A. I. Morrison-Shetlar

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Both Na+/H+ exchange and the electrogenic extrusion of H+ via an H+-ATPase have been postulated to drive acid excretion across the branchial epithelium of fishes. While the H+-ATPase/Na+ channel system appears to be the predominant mechanism in some freshwater species, it may play a reduced role in seawater and brackish-water animals, where high external Na+ concentrations may thermodynamically favor Na+/H+ exchange driven by a Na+/H+ antiporter (NHE). In this study, we used molecular and immunological methods to assess the role of NHE isoforms in the branchial epithelium of the marine long-horned sculpin (Myoxocephalus octodecimspinosus) and the euryhaline killifish (Fundulus heteroclitus). Northern blot analysis of RNA probed with the human NHE-1 BamHI fragment suggested the presence of homologous gill NHE mRNA in sculpin. RT-PCR on gill RNA isolated from sculpin recovering from metabolic acidosis provided evidence for two distinct NHE isoforms; one with 76% amino acid homology to mammalian NHE-2, and another 92% homologous to trout erythrocytic β-NHE. Killifish also have transcripts with 91% homology to β-NHE. Immunological detection using monoclonal antibodies for mammalian NHE-1 revealed a protein antigenically similar to this isoform in the gills of both species. Metabolic acidosis caused an approximately 30-fold decrease in expression of the NHE-1-like protein in sculpin. We speculate that β-NHE in the gills plays the intracellular 'housekeeping' roles described for mammalian NHE-1. During systemic acidosis, apical gill NHE-2 (which is sensitive to external amiloride and low [Na+]) in parallel with a dramatic suppression of basolateral NHE-1 activity enhances net AH+ transfers to the water.

Original languageEnglish (US)
Pages (from-to)315-324
Number of pages10
JournalJournal of Experimental Biology
Volume202
Issue number3
StatePublished - Feb 1999
Externally publishedYes

Fingerprint

Sodium-Hydrogen Antiporter
Seawater
teleost
homology
excretion
marine fish
RNA
gills
Protein Isoforms
Fishes
seawater
Acids
protein
acids
acid
fish
extrusion
brackish water
antibody
amino acid

Keywords

  • Acid-base
  • Euryhaline
  • Fundulus heteroclitus
  • Gill
  • H excretion
  • Killifish
  • Myoxocephalus octodecimspinosus
  • PH balance
  • Salinity
  • Sculpin
  • Stenohaline

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Agricultural and Biological Sciences (miscellaneous)

Cite this

Claiborne, J. B., Blackston, C. R., Choe, K. P., Dawson, D. C., Harris, S. P., Mackenzie, L. A., & Morrison-Shetlar, A. I. (1999). A mechanism for branchial acid excretion in marine fish: Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts. Journal of Experimental Biology, 202(3), 315-324.

A mechanism for branchial acid excretion in marine fish : Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts. / Claiborne, J. B.; Blackston, C. R.; Choe, K. P.; Dawson, D. C.; Harris, S. P.; Mackenzie, L. A.; Morrison-Shetlar, A. I.

In: Journal of Experimental Biology, Vol. 202, No. 3, 02.1999, p. 315-324.

Research output: Contribution to journalArticle

Claiborne, JB, Blackston, CR, Choe, KP, Dawson, DC, Harris, SP, Mackenzie, LA & Morrison-Shetlar, AI 1999, 'A mechanism for branchial acid excretion in marine fish: Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts', Journal of Experimental Biology, vol. 202, no. 3, pp. 315-324.
Claiborne, J. B. ; Blackston, C. R. ; Choe, K. P. ; Dawson, D. C. ; Harris, S. P. ; Mackenzie, L. A. ; Morrison-Shetlar, A. I. / A mechanism for branchial acid excretion in marine fish : Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts. In: Journal of Experimental Biology. 1999 ; Vol. 202, No. 3. pp. 315-324.
@article{5e0148a82dac4ca2b8c7f9ba56d3a92b,
title = "A mechanism for branchial acid excretion in marine fish: Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts",
abstract = "Both Na+/H+ exchange and the electrogenic extrusion of H+ via an H+-ATPase have been postulated to drive acid excretion across the branchial epithelium of fishes. While the H+-ATPase/Na+ channel system appears to be the predominant mechanism in some freshwater species, it may play a reduced role in seawater and brackish-water animals, where high external Na+ concentrations may thermodynamically favor Na+/H+ exchange driven by a Na+/H+ antiporter (NHE). In this study, we used molecular and immunological methods to assess the role of NHE isoforms in the branchial epithelium of the marine long-horned sculpin (Myoxocephalus octodecimspinosus) and the euryhaline killifish (Fundulus heteroclitus). Northern blot analysis of RNA probed with the human NHE-1 BamHI fragment suggested the presence of homologous gill NHE mRNA in sculpin. RT-PCR on gill RNA isolated from sculpin recovering from metabolic acidosis provided evidence for two distinct NHE isoforms; one with 76{\%} amino acid homology to mammalian NHE-2, and another 92{\%} homologous to trout erythrocytic β-NHE. Killifish also have transcripts with 91{\%} homology to β-NHE. Immunological detection using monoclonal antibodies for mammalian NHE-1 revealed a protein antigenically similar to this isoform in the gills of both species. Metabolic acidosis caused an approximately 30-fold decrease in expression of the NHE-1-like protein in sculpin. We speculate that β-NHE in the gills plays the intracellular 'housekeeping' roles described for mammalian NHE-1. During systemic acidosis, apical gill NHE-2 (which is sensitive to external amiloride and low [Na+]) in parallel with a dramatic suppression of basolateral NHE-1 activity enhances net AH+ transfers to the water.",
keywords = "Acid-base, Euryhaline, Fundulus heteroclitus, Gill, H excretion, Killifish, Myoxocephalus octodecimspinosus, PH balance, Salinity, Sculpin, Stenohaline",
author = "Claiborne, {J. B.} and Blackston, {C. R.} and Choe, {K. P.} and Dawson, {D. C.} and Harris, {S. P.} and Mackenzie, {L. A.} and Morrison-Shetlar, {A. I.}",
year = "1999",
month = "2",
language = "English (US)",
volume = "202",
pages = "315--324",
journal = "Journal of Experimental Biology",
issn = "0022-0949",
publisher = "Company of Biologists Ltd",
number = "3",

}

TY - JOUR

T1 - A mechanism for branchial acid excretion in marine fish

T2 - Identification of multiple Na+/H+ antiporter (NHE) isoforms in gills of two seawater teleosts

AU - Claiborne, J. B.

AU - Blackston, C. R.

AU - Choe, K. P.

AU - Dawson, D. C.

AU - Harris, S. P.

AU - Mackenzie, L. A.

AU - Morrison-Shetlar, A. I.

PY - 1999/2

Y1 - 1999/2

N2 - Both Na+/H+ exchange and the electrogenic extrusion of H+ via an H+-ATPase have been postulated to drive acid excretion across the branchial epithelium of fishes. While the H+-ATPase/Na+ channel system appears to be the predominant mechanism in some freshwater species, it may play a reduced role in seawater and brackish-water animals, where high external Na+ concentrations may thermodynamically favor Na+/H+ exchange driven by a Na+/H+ antiporter (NHE). In this study, we used molecular and immunological methods to assess the role of NHE isoforms in the branchial epithelium of the marine long-horned sculpin (Myoxocephalus octodecimspinosus) and the euryhaline killifish (Fundulus heteroclitus). Northern blot analysis of RNA probed with the human NHE-1 BamHI fragment suggested the presence of homologous gill NHE mRNA in sculpin. RT-PCR on gill RNA isolated from sculpin recovering from metabolic acidosis provided evidence for two distinct NHE isoforms; one with 76% amino acid homology to mammalian NHE-2, and another 92% homologous to trout erythrocytic β-NHE. Killifish also have transcripts with 91% homology to β-NHE. Immunological detection using monoclonal antibodies for mammalian NHE-1 revealed a protein antigenically similar to this isoform in the gills of both species. Metabolic acidosis caused an approximately 30-fold decrease in expression of the NHE-1-like protein in sculpin. We speculate that β-NHE in the gills plays the intracellular 'housekeeping' roles described for mammalian NHE-1. During systemic acidosis, apical gill NHE-2 (which is sensitive to external amiloride and low [Na+]) in parallel with a dramatic suppression of basolateral NHE-1 activity enhances net AH+ transfers to the water.

AB - Both Na+/H+ exchange and the electrogenic extrusion of H+ via an H+-ATPase have been postulated to drive acid excretion across the branchial epithelium of fishes. While the H+-ATPase/Na+ channel system appears to be the predominant mechanism in some freshwater species, it may play a reduced role in seawater and brackish-water animals, where high external Na+ concentrations may thermodynamically favor Na+/H+ exchange driven by a Na+/H+ antiporter (NHE). In this study, we used molecular and immunological methods to assess the role of NHE isoforms in the branchial epithelium of the marine long-horned sculpin (Myoxocephalus octodecimspinosus) and the euryhaline killifish (Fundulus heteroclitus). Northern blot analysis of RNA probed with the human NHE-1 BamHI fragment suggested the presence of homologous gill NHE mRNA in sculpin. RT-PCR on gill RNA isolated from sculpin recovering from metabolic acidosis provided evidence for two distinct NHE isoforms; one with 76% amino acid homology to mammalian NHE-2, and another 92% homologous to trout erythrocytic β-NHE. Killifish also have transcripts with 91% homology to β-NHE. Immunological detection using monoclonal antibodies for mammalian NHE-1 revealed a protein antigenically similar to this isoform in the gills of both species. Metabolic acidosis caused an approximately 30-fold decrease in expression of the NHE-1-like protein in sculpin. We speculate that β-NHE in the gills plays the intracellular 'housekeeping' roles described for mammalian NHE-1. During systemic acidosis, apical gill NHE-2 (which is sensitive to external amiloride and low [Na+]) in parallel with a dramatic suppression of basolateral NHE-1 activity enhances net AH+ transfers to the water.

KW - Acid-base

KW - Euryhaline

KW - Fundulus heteroclitus

KW - Gill

KW - H excretion

KW - Killifish

KW - Myoxocephalus octodecimspinosus

KW - PH balance

KW - Salinity

KW - Sculpin

KW - Stenohaline

UR - http://www.scopus.com/inward/record.url?scp=0033083220&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033083220&partnerID=8YFLogxK

M3 - Article

VL - 202

SP - 315

EP - 324

JO - Journal of Experimental Biology

JF - Journal of Experimental Biology

SN - 0022-0949

IS - 3

ER -