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.
