Aldosterone regulates salivary sodium secretion in cattle

Intravenous infusion of aldosterone (10 microgram/kg body wt per h for 5 h) in four 2-month-old calves decreased salivary and urinary sodium (Na+) concentration and increased salivary potassium (K+) concentration without modifying salivary flow or urinary K+ concentration. Intravenous angiotensin II infusion (0.3 microgram/kg body wt per min for 1 h) in four Na+-replete 16-month-old bulls decreased salivary Na+ concentration and increased that of K+. It also increased plasma cortisol and plasma aldosterone concentrations, and decreased plasma renin activity (PRA). In four 16-month-old bulls Na+ deficiency (induced by chronic cannulation of the right parotid duct and loss of saliva for 5 days) had similar effects to those observed following aldosterone infusion in calves: a decrease in salivary Na+/K+ ratio. This decrease was associated with an increase in PRA and an increase in plasma aldosterone concentration. In these animals a close positive relationship was observed between PRA and plasma aldosterone concentration (r = 0.91; n = 20; P less than 0.01). Thus in cattle, during Na+ deficiency, the effect of aldosterone on parotid glands participates in the regulation of Na+ metabolism.