When is cortisol a mineralocorticoid?
(1) Decreased 11 beta-OHSD activity permits binding of cortisol to the Type I (mineralocorticoid) receptor in humans, thereby producing spironolactone-inhibitable Na+ retention, hypokalemia and hypertension, the syndrome of apparent mineralocorticoid excess (AME). (2) Blockade of either the Type I receptor with spironolactone or the Type II (glucocorticoid) receptor with RU-486 does not consistently abolish the effects of stress level cortisol on Na+ retention and hypertension in acute studies in normal humans, suggesting the existence of an additional glucocorticoid receptor. (3) Enhanced glucocorticoid 6 beta-hydroxylation could play an etiologic role in certain hypertensive syndromes. (4) Both decreased 11 beta-OHSD and increased 6 beta-OHase are candidates as intermediate phenotypes for the remote phenotype essential hypertension.