Secretion from the cortex-free bovine adrenal medulla.

1. The isolated bovine adrenal medulla was prepared from whole glands by careful removal of the cortex. The tissue was perfused with physiological salt solution and stimulated with a variety of secretogogues.2. Catecholamines were secreted from the tissue upon stimulation with carbamylcholine, nicotine sulphate, acetylcholine bromide, histamine dihydrochloride, (+)-amphetamine sulphate and potassium chloride.3. Carbachol-induced secretion of catecholamines was reduced in the presence of either hexamethonium bromide or tetracaine hydrochloride, during perfusion with calcium-free perfusion fluid, or during perfusion at low temperature.4. Stimulation of the medulla with carbachol also led to secretion of chromaffin granule protein and acid deoxyribonuclease. The relationships between catecholamines secreted and the amounts of these proteins secreted were similar to the corresponding values for the perfused whole bovine adrenal gland. Perfusate lactate dehydrogenase activity and perfusate haemoglobin content were unchanged after carbachol stimulation.5. It is concluded that there are no differences in the mechanisms for catecholamine secretion from the cortex-free perfused medulla and the perfused whole gland.