Branchial ion exchange and acid-base regulation after strenuous exercise in rainbow trout (Salmo gairdneri)

Respir Physiol. 1983 Mar;51(3):303-18. doi: 10.1016/0034-5687(83)90025-7.


Specimens of rainbow trout (Salmo gairdneri) were electrically stimulated to exhausting activity in a closed water recirculation system and the changes in dorsal aortic plasma pH, PCO2, PO2, O2 content, [Na+], [Cl-], [K+], [Lactate-] and Ht were measured during a 24 h recovery period. Net transfer of H+, Na+, Cl- and ammonia between fish and environment were determined by measurement of the concentration changes in the recirculating water. Strenuous exercise resulted in a severe lactacidosis which was corrected by transient net transfer of H+ ions to the environmental water within 4 h, about 6-8 h before the lactate was metabolically removed. The net transfer of H+ ions was achieved in part by branchial HCO3-/Cl- ion exchanges, but to a larger extent by branchial exchange of H+ and/or NH4+ against Na+. The excretion of ammonia, which was considerably enhanced during the first 4 h after exercise, was at least partially due to non-ionic diffusion across the gill epithelium. The observed elevation in ammonia excretion was probably the result of an exercise-induced increase in nitrogen metabolism rather than of production of ammonia for the purpose of acid-base regulation.

MeSH terms

  • Acid-Base Equilibrium*
  • Acidosis / metabolism
  • Ammonia / metabolism
  • Animals
  • Bicarbonates / metabolism
  • Gills / metabolism*
  • Gills / physiology
  • Hydrogen-Ion Concentration
  • Ion Exchange
  • Lactates
  • Physical Exertion*
  • Salmonidae / physiology*
  • Trout / physiology*


  • Bicarbonates
  • Lactates
  • Ammonia