No Man's Sky

Not sure how it's supposed to be used exactly, but it's being fed into your life support system to boost it. If any body part would be directly impacted by a change in that system, lungs would be an obvious candidate.

Maybe using it changes the composition of whatever the life support system makes you breathe, or yeah, maybe it's a liquid sent directly into your lungs like that stuff they use in The Abyss.

Of which the rat experiment part was a real thing apparently. They just had to use shots from 5 different fluid-breathing rats because the poor fuckers were so panicked they shat themselves constantly in terror.