1. In rat parotid acini, amiloride inhibited the secretion of amylase and the efflux of calcium and rubidium in response to carbamylcholine and to norepinephrine.
2. Amiloride competitively inhibited the binding of [H-3]N-methylscopolamine and [H-3] is thus a competitive antagonist of muscarinic and norepinephrine alpha-adrenergic receptors.
3. Amiloride did not affect the response to substance P with respect to secretion or ion movements.
4. Thus the Na+/H+ antiporter is not involved in the short-term regulation of amylase secretion and calcium and potassium movements in rat parotid gland function.