1. The blood pressure, renal and metabolic effects of adrenocorticotropic hormone (ACTH) have been studied in six normotensive subjects and two patients with Addison's disease on maintenance steroid therapy.
2. In normotensive subjects, 5 days ACTH treatment (0.5 mg 12 hourly) was associated with a rise in systolic blood pressure and mean arterial pressure. There was a small rise in diastolic pressure but no consistent change in heart rate. Plasma sodium increased and plasma potassium fell. Serum creatinine and urea concentrations were unchanged. Fluid intake increased and urine output was unchanged but ACTH withdrawal was associated with a diuresis. There was an initial reduction in urinary sodium excretion and a natriuresis after ACTH withdrawal. Plasma volume and body weight rose.
3. ACTH produced increases in plasma cortisol, 11-deoxycortisol, corticosterone, deoxycorticosterone, aldosterone, 17α-hydroxyprogesterone and 17α,20α-dihydroxyprogesterone. Plasma renin concentration fell.
4. Patients with Addison's disease showed no change in blood pressure or in any other metabolic variable studied.
5. The effects of ACTH in man resembled those found in sheep.