Recent progress in understanding aldosterone secretion

1. 1. The synthesis and secretion of aldosterone in the adrenal zona glomerulosa in physiologic conditions is controlled by adrenocorticotropin (ACTH), angiotensin II (AII), and extracellular (K +). 2. 2. ACTH effects on aldosterone output are explained by cyclic AMP- (cAMP)- and Ca 2+-dependent mechanisms. 3. 3. All effects on aldosterone secretion are initiated by an increase in Ca 2+ influx through hormone-operated Ca 2+ channels and G-protein- and phospholipase C- (PLC) dependent hydrolysis of phosphoinositides leading to the generation of inositol 1,4,5 trisphosphate (IP 3) and DAG that induce intracellular Ca 2+ release and PKC activation, respectively. 4. 4. ACTH increases DAG formation with marginal or undetectable IP 3 generation. The effect of ACTH on DAG levels is discussed. 5. 5. The requirement of external Ca 2+ in PLC activation and aldosterone secretion also is discussed.