Effects of short-term changes in electrolyte intake on the adrenal steroidogenic responses of juvenile mallard ducks (Anas platyrhynchos).

1. Adjusting the Na+ and K+ intake of juvenile mallard ducks caused the plasma concentrations of corticosterone (B) and aldosterone (Aldo) to increase independently of one another, but none of these changes in electrolyte intake had a significant effect on the deoxycorticosterone (DOC) concentration. 2. With the exception of DOC in birds consuming the control diet, the plasma concentration of each hormone, regardless of diet, increased significantly following exposure to stress. 3. Stress-induced increases in Aldo concentration were greatest in birds given diets containing low concentrations of Na+. 4. Unlike the mammal and some other species of birds, Na+ may be the primary secretagogue responsible for the regulation of both corticosterone and aldosterone synthesis in the mallard duck.