Stimulation of Aldosterone Secretion by Angiotensin II

The role of the renin-angiotensin system in renal hypertension has been investigated for many years but the relationship of the renin-angiotensin system to adrenocortical function has received less attention. In 1951, Deane and Masson,4 using the rat as an experimental animal, reported that encapsulation of the kidney, a procedure which results in hypertension presumably through release of renin, and injections of crude renin preparations both produced enlargement of the zona glomerulosa of the adrenal gland, the site of aldosterone formation. Hartroft and co-workers" noted that salt loading in the rat decreased both the granulations of the juxtaglomerular apparatus (the probable site of renin formation) and the content of renin in the kidney, while sodium deprivation increased the granulations and the content of renin. An excellent review by Tobian1' has summarized the data concerning the possible role of the renin-angiotensin system in electrolyte metabolism and hypertension. Recently prolonged infusions of synthetic angiotensin into man have been reported as producing a pressor response and an increase in aldosterone excretion and secretion."'10 It is a possibility that the aldosterone effect was an indirect one through angiotensin stimulating ACTH release from the pituitary. In fact, Geneste found that the angiotensin infusion also increased urinary tetrahydrocortisol excretion. Experiments conducted independently by Davis and co-workers8 and the authors' have implicated the kidney and the reninangiotensin system in the increased aldosterone secretion that occurs fol-