Potassium modulation of corticosterone secretion from perifused mouse adrenal cells

Potassium has long been recognized as a significant modulator of aldosterone synthesis and secretion. Its role as a regulator of glucocorticoids is less clear. Using a perifusion of dispersed mouse adrenal cells, we found a dose-related effect of extracellular potassium (K+) on secretion of the major rodent glucocorticoid, corticosterone. The maximal elicitable responses was 33% of the maximal response to ACTH. An increase in K+ concentration enhanced the effect of ACTH, while K+-free medium depressed the response to ACTH. The temporal characteristics of the corticosterone response to K+ were similar to that of ACTH and consistent with a primary effect on biosynthesis rather than on discharge of a preformed pool of hormone. The results indicate that a significant ion-mediated mechanism modulates ACTH-stimulated glucocorticoid secretion and suggest that further studies of endogenous substances operative by ionic mechanisms might be warranted.