Abstract
It is well known that the regulation of aldosterone secretion is governed by the reninangiotensin system, ACTH and electrolytes (Na and K) in plasma. However, the relationships between these regulating factors of aldosterone secretion still remain unclear. In order to study the relationships between these regulating factors of aldosterone, we examined the effects of angiotensin II plus ACTH under various conditions on plasma aldosterone in normal subjects.
Men aged 19-23 years were selected for testing. Using 4 groups, containing 5 men each, the following experiment was performed. Group I : Angiotensin II (5 ng/kg/min.) was infused at 1800 hours. Group II : β1-24 ACTH (0.25 mg) was injected intravenously at 1800 hours. Group III : Infusion of angiotension II and injection of ACTH were performed at 1800 hours. Group IV : Infusion of angiotensin II was performed at 1700 hours and injection of ACTH was performed at 1800 hours.
In Group I, plasma aldosterone increased with maximum peak attained 60 minutes after infusion of angiotensin II. In Group II, plasma aldosterone increased with maximum peak attained 60 minutes after injection of ACTH. In Group III, plasma aldosterone increased after infusion of angiotensin II plus injection of ACTH more significantly than after infusion of angiotensin II or injection of ACTH. In Group IV, plasma aldosterone increased after infusion of angiotensin II and continuously increased after injection of ACTH.
From these results, we concluded that infusion of angiotensin II and injection of ACTH at the same time cause additional increase in plasma aldosterone, and that not only preceding stimulation (angiotensin II), but also following stimulation (ACTH) cause an increase in plasma aldosterone.
