Sodium ions and the secretion of catecholamines.

1. Perfusion of bovine adrenal glands with a potassium-free Tyrode solution results in an increased spontaneous release of catecholamines and an increased response to stimulation with carbamylcholine.2. Perfusion with a Tyrode solution containing 70 mM-KCl causes a marked secretion of catecholamines and a subsequent inhibition of secretion in response to stimulation with carbamylcholine.3. Perfusion with sodium-free media abolishes or severely reduces the secretory response of the gland to carbamylcholine and to 70 mM-KCl although the basal secretion shows an initial rise.4. Perfusion with sodium-deficient media permits some retention of the secretory response.5. A possible role for intracellular sodium ions in the secretion of catecholamines is discussed.