Ion regulation in fish gills: Recent progress in the cellular and molecular mechanisms

Pung Pung Hwang*, Tsung Han Lee, Li Yih Lin

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

429 Citations (Scopus)


Fish encounter harsh ionic/osmotic gradients on their aquatic environments, and the mechanisms through which they maintain internal homeostasis are more challenging compared with those of terrestrial vertebrates. Gills are one of the major organs conducting the internal ionic and acid-base regulation, with specialized ionocytes as the major cells carrying out active transport of ions. Exploring the iono/osmoregulatory mechanisms in fish gills, extensive literature proposed several models, with many conflicting or unsolved issues. Recent studies emerged, shedding light on these issues with new opened windows on other aspects, on account of available advanced molecular/cellular physiological approaches and animal models. Respective types of ionocytes and ion transporters, and the relevant regulators for the mechanisms of NaCl secretion, Na+ uptake/acid secretion/NH4+ excretion, Ca2+ uptake, and Cl- uptake/base secretion, were identified and functionally characterized. These new ideas broadened our understanding of the molecular/cellular mechanisms behind the functional modification/regulation of fish gill ion transport during acute and long-term acclimation to environmental challenges. Moreover, a model for the systematic and local carbohydrate energy supply to gill ionocytes during these acclimation processes was also proposed. These provide powerful platforms to precisely study transport pathways and functional regulation of specific ions, transporters, and ionocytes; however, very few model species were established so far, whereas more efforts are needed in other species.

Original languageEnglish
Pages (from-to)R28-R47
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number1
Publication statusPublished - 2011 Jul


  • Acid-base regulation
  • Ammonia excretion
  • Energy supply
  • Functional regulation
  • Ion uptake
  • Ionocytes
  • NaCl secretion
  • Transporters

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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