Interaction of amiloride with rat parotid muscarinic and alpha-adrenergic receptors.

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 [3H]N-methylscopolamine and [3H] 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.