Respiratory control of acid-base status in lungfish

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  • Bruna L.C.Z. Nunan, Minas Gerais Federal University
  • ,
  • Ayla S. Silva, Minas Gerais Federal University
  • ,
  • Tobias Wang
  • Glauber S.F. da Silva, Minas Gerais Federal University

The acid-base status is a tightly regulated physiological process, resulting from a balance of ions in the organism relevant to acid-base. The efficiency of the regulatory systems importantly determines the compensatory pH changes for a given disturb. Vertebrates minimize (or compensate) an acid-base disturb by general processes, which include ion transfer and/or PCO2 changes. Acid–base adjustment in fish is predominantly achieved by branchial exchange of acid-base relevant ions with correlated change in plasma HCO3 levels. Conversely, land vertebrates change blood PCO2 through ventilatory process and hence respiratory control of acid–base regulation plays an important role as a compensatory mechanism. Lungfishes (Dipnoi) have central position on vertebrate's evolution being considered as the sister group to the tetrapods. With an aquatic life mode, lungfish share similarities of respiratory function with tetrapods. This article reviews evidence showing that lungfish's respiratory system regulates acid-base status, like terrestrial ectothermic vertebrates. In the South American lungfish, Lepidosiren paradoxa, the presence of central CO2/pH chemoreceptors was unequivocally described. Also, the blood PCO2 and acid-base status are typical of a terrestrial vertebrate. These aspects are discussed under different environmental conditions that require respiratory acid-base adjustments, such as, exposure to hypercarbia, hypoxia, high temperature and aestivation. Interesting questions regarding the location and cell phenotype of CO2/pH central and peripheral chemoreceptors remain an open field to be explored in lungfish.

Original languageEnglish
Article number110533
JournalComparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology
Volume237
ISSN1095-6433
DOIs
Publication statusPublished - Nov 2019

    Research areas

  • Aestivation, Blood gases, Central chemoreception, CO-chemoreceptors, Lepdosiren paradoxa, South American lungfish, Tetrapods, Ventilation

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