The chloride cell: structure and function in the gills of freshwater fishes

Annu Rev Physiol. 1997;59:325-47. doi: 10.1146/annurev.physiol.59.1.325.


This review focuses on the structure and function of the branchial chloride cell in freshwater fishes. The mitochondria-rich chloride cell is believed to be the principal site of trans-epithelial Ca2+ and Cl- influxes. Though currently debated, there is accruing evidence that the pavement cell is the site of Na+ uptake via channels linked electrically to an apical membrane vacuolar H(+)-ATPase (proton pump). Chloride cells perform an integral role in acid-base regulation. During conditions of alkalosis, the surface area of exposed chloride cells is increased, which serves to enhance base equivalent excretion as the rate of Cl-/HCO3- exchange is increased. Conversely, during acidosis, the chloride cell surface area is diminished by an expansion of the adjacent pavement cells. This response reduces the number of functional Cl-/HCO3- exchangers. Under certain conditions that challenge ion regulation, chloride cells proliferate on the lamellae. This response, while optimizing the Ca2+ and Cl- transport capacity of the gill, causes a thickening of the blood-to-water diffusion barrier and thus impedes respiratory gas transfer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Acid-Base Equilibrium / physiology
  • Animals
  • Chlorides / metabolism*
  • Fishes / anatomy & histology*
  • Fishes / physiology*
  • Gills / anatomy & histology*
  • Gills / cytology
  • Gills / physiology*
  • Ions
  • Respiration / physiology


  • Chlorides
  • Ions