Remarkable blood catecholamine levels in forced dived ducks.

Levels of circulating epinephrine (E) and nor-epinephrine (NE) were measured in duck blood before, during, and after forced dives which were extended close to the limit of underwater endurance. Both E and NE increased by, on occasion, three orders of magnitude. After surfacing, plasma catecholamine levels fell rapidly. The reason for this enormous amine release in forced dived ducks remains a matter of speculation.