The effect of perfusate oxygen levels on CO2 excretion in the perfused gill

CO2 excretion across the perfused trout gill was found to fall to levels approaching zero after 20–30 minutes perfusion with perfusates with oxygen tensions at atmospheric levels. When perfusate oxygen levels were lowered by bubbling with nitrogen, CO2 excretion rates remained stable at least 4–6 hours. The ability to maintain a viable perfused gill preparation with respect to CO2 excretion may also be directly applicable to related studies, e.g. gill ion regulation.