To the Editor.
—The basic science review by Ian A. Reid, PhD, in the August 1985 issue of the Archives clearly discussed the plasma renin-angiotensin-aldosterone system and stressed the numerous factors implicated in the control of this system. In particular, the control of renin secretion by intrarenal vascular receptors, the macula densa, the renal nerves, and several circulating factors (eg, epinephrine, potassium, angiotensin II, and vasopressin) was noted. We have seen the suppression of plasma renin activity (PRA) during a short-acting adrenocorticotropic hormone (ACTH) test using intravenous cosyntropin (β1-24-corticotrophin, Synacthen, Ciba-Geigy) performed in five patients.All patients were evaluated at midday, after being supine for more than four hours. Blood sampling was performed at 0, 30, and 60 minutes following an intravenous bolus of 250 μg of cosyntropin. Standard precautions with a heparinized indwelling infusion set was used in order to avoid any stress-related effects. Plasma renin