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Rates of hypoxia induction alter mechanisms of O2 uptake and the critical O2 tension of goldfish

Synopsis:

What we did: We used goldfish to explore how an animal’s response to, and performance in, hypoxia is affected by the rate of hypoxia induction, a dimension of hypoxia that has never been investigated.

What we found: Low rates of hypoxia induction allowed goldfish more time to significantly increase their gill surface areas and maintain significantly higher hemoglobin-oxygen binding affinities than goldfish exposed to high rates of hypoxia induction. Consequently, fish exposed to low rates of hypoxia induction could maintain routine rates of aerobic metabolism at oxygen levels twice as low as fish exposed to high rates of hypoxia induction (ie, a twofold lower critical oxygen tension, Pcrit).

What this means: The rate of hypoxia induction significantly impacts the hypoxic responses of animals. It may be that an animal’s hypoxia responses are well tuned to the rates of hypoxia induction that are typical of its natural environment. Therefore, the rate of induction must be accounted for when experimentally exposing animals to hypoxia.