Effect of natrium ionophore on aldosterone production in the rat adrenal gland.

The effect of the natrium ionophore, monensin, on aldosterone production was studied using rat adrenal collagenase-dispersed capsular cells. Monensin inhibited aldosterone production in a dose-dependent fashion (10(-9)-10(-6)M). Although monensin inhibited both ACTH- and angiotensin II (AT-II)-stimulated aldosterone production, its inhibitory effect on ACTH-stimulated aldosterone production was greater than that on AT-II-stimulated aldosterone production. The inhibitory effect of monensin on aldosterone production was not accompanied by significant changes in cAMP production. Furthermore, (Bu)2cAMP-stimulated aldosterone production was inhibited by monensin. These results suggest that the inhibitory effect of monensin on aldosterone production is due to an increase in intracellular sodium ion concentration, and that monensin acts at step(s) distal to the generation of cAMP. The differences in the inhibitory effects of monensin on the steroidogenic action of AT-II and that of ACTH may be related to the presence of different steroidogenic mechanisms, including calcium ion dependency.