Catecholamine hormones and the control of avian salt glands

Hypertonic saline loading (0.5 M NaCl, 15 ml.kg-1 i.v.) increased cardiac frequency and elicited nasal salt gland secretion in control ducks. Partial depletion of catecholamines by prior treatment with reserpine decreased body weight, lowered arterial pressure and abolished the tachycardiac responses to saline loading. Reserpine also increased plasma concentrations of Na, K and total osmolytes, yet altered neither the composition nor the flow rate of nasal fluid secretion. The preservation of the normal secretory responses to hypertonic stress in hypotensive, reserpine-treated ducks indicates that the nasal salt glands can function independently of changes in circulating catecholamine hormones.