Sensitivity of CO2 excretion to blood flow changes in trout is determined by carbonic anhydrase availability.

The blood transit time through the gills of rainbow trout (Oncorhynchus mykiss) was modified by manipulation of cardiac output (Vb). The experiments tested the hypothesis that efficiency of CO2 excretion is sensitive to changes in blood flow owing to chemical equilibrium limitations. An extracorporeal blood shunt was used to continuously monitor blood gases in fish in which Vb was elevated (by 13.