Water balance and renal function in two species of African lungfish Protopterus dolloi and Protopterus annectens

Monika Patel, Fathima I. Iftikar, Richard W. Smith, Yuen K. Ip, Chris M. Wood

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The basic physiology of water balance and kidney function was characterized in two species of African lungfish, Protopterus dolloi and Protopterus annectens. Diffusive water efflux rate constants were low (0.13 h- 1-0.38 h- 1 in various series) relative to values in freshwater teleost fish. Efflux rate constants increased approximately 3-fold after feeding in both species, and were greatly decreased after 8 months terrestrialization (P. dolloi only tested). Urine flow rates (UFR, 3.9-5.2 mL kg- 1 h- 1) and glomerular filtration rates (GFR, 6.6-9.3 mL kg- 1 h- 1) were quite high relative to values in most freshwater teleosts. However urinary ion excretion rates were low, with net re-absorption of > 99% Na+, > 98% Cl-, and > 78% Ca2+ from the primary filtrate, comparable to teleosts. Net water re-absorption was significantly greater in P. dolloi (56%) than in P. annectens (23%). We conclude that renal function in lungfish is similar to that in other primitive freshwater fish, but there is an interesting dichotomy between diffusive and osmotic permeabilities. Aquatic lungfish have low diffusive water permeability, an important pre-adaptation to life on land, and in accord with greatly reduced gill areas and low metabolic rates. However osmotic permeability is high, 4-12 times greater than diffusive permeability. A role for aquaporins in this dichotomy is speculated.

Original languageEnglish (US)
Pages (from-to)149-157
Number of pages9
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Issue number2
StatePublished - Feb 2009


  • Clearance ratio
  • Diffusive permeability
  • Feeding
  • Osmotic permeability
  • Terrestrialization

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Physiology


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