An Analysis of Acid Vase, Ionic and Water Balance in Rainbow Trout (Salmo gairdneri) Exercised at Cruising Speeds

Abstract

Rainbow trout (Salmo gairdneri) were exercised at cruising speeds for 5 hours. A slight but significant increase in dorsal aortic blood pH after I hour of exercise was accompanied by significant decreases in PeDl and total C02 content of blood. These changes were maintained throughout the exercise period of 5 hours. This respiratory alkalosis could be due to hyperventilation and/or the result of increased uptake of Na+ and Cl- which occurred along with the increase in plasma volume in order to maintain normal osmotic concentrations. The uptake of Na+ and CI- occurred presumably via branchial Na+ /H+ and CI- /HCO; ion exchange mechanisms.