Na+/K+-ATPase and vacuolar-type H+-ATPase in the gills of the aquatic air-breathing fish Trichogaster microlepis in response to salinity variation

Comp Biochem Physiol A Mol Integr Physiol. 2010 Mar;155(3):309-18. doi: 10.1016/j.cbpa.2009.11.010. Epub 2009 Nov 18.


The aquatic air-breathing fish, Trichogaster microlepis, can be found in fresh water and estuaries. We further evaluated the changes in two important osmoregulatory enzymes, Na(+)/K(+)-ATPase (NKA) and vacuolar-type H(+)-ATPase (VHA), in the gills when fish were subjected to deionized water (DW), fresh water (FW), and salinated brackish water (salinity of 10 g/L). Fish were sampled only 4 days after experimental transfer. The mortality, plasma osmolality, and Na(+) concentration were higher in 10 g/L acclimated fish, while their muscle water content decreased with elevated external salinity. The highest NKA protein abundance was found in the fish gills in 10 g/L, and NKA activity was highest in the DW and 10 g/L acclimated fish. The VHA protein levels were highest in 10 g/L, and VHA activity was highest in the DW treatment. From immunohistochemical results, we found three different cell populations: (1) NKA-immunoreactive (NKA-IR) cells, (2) both NKA-IR and HA-IR cells, and (3) HA-IR cells. NKA-IR cells in the lamellar and interlamellar regions significantly increased in DW and 10 g/L treatments. Only HA-IR cells in the lamellar region were significantly increased in DW. In the interlamellar region, there was no difference in the number of HA-IR cells among the three treated. From these results, T. microlepis exhibited osmoregulatory ability in DW and 10 g/L treatments. The cell types involved in ionic regulation were also examined with immunofluorescence staining; three ionocyte types were found which were similar to the zebrafish model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air*
  • Animals
  • Fish Proteins / metabolism
  • Fishes / blood
  • Fishes / physiology*
  • Fluorescent Antibody Technique
  • Gills / cytology
  • Gills / enzymology*
  • Immunoblotting
  • Microscopy, Confocal
  • Muscles / metabolism
  • Osmolar Concentration
  • Oxygen Consumption / physiology*
  • Salinity*
  • Sodium-Potassium-Chloride Symporters / metabolism
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Survival Analysis
  • Vacuolar Proton-Translocating ATPases / metabolism*
  • Water / metabolism


  • Fish Proteins
  • Sodium-Potassium-Chloride Symporters
  • Water
  • Vacuolar Proton-Translocating ATPases
  • Sodium-Potassium-Exchanging ATPase