Potassium, corticosterone, and adrenocorticotropic hormone release in vitro.

Incubation of rat adenohypophyses in a high concentration of potassium increases adrenocorticotropic hormone release. This increased release is suppressed by the addition of corticosterone to the incubating medium. Our findings are consistent with a process of "stimulus-secretion coupling" proposed for other glands and suggest that corticosterone may operate directly on the adenohypophysial cell membrane to inhibit releasing mechanisms.