1. To assess whether the adrenal corticosteroid 18-hydroxy-11-deoxycorticosterone [18-(OH)DOC] affects urine electrolyte excretion in normal man, seven male volunteers received 120 μg (353 nmol) intravenously in 1 h. This was compared with glucose (50 g/l; control) and aldosterone (80 μg, 222 nmol) infusions in the same subjects.
2. A definite though weak antinatriuretic response to 18-(OH)DOC was observed, whereas urine potassium excretion was not altered. Aldosterone increased urine potassium excretion and reduced sodium output. Urine pH was lowered by both corticosteroids, aldosterone in general having a more marked effect. Urine volume was not altered by 18-(OH)DOC.
3. Plasma concentrations of 18-(OH)DOC and aldosterone rose approximately tenfold during their respective infusions. Compared with that of aldosterone, the metabolic clearance rate of 18-(OH)DOC was slower and its plasma half-life was longer.
4. We have been able to demonstrate that 18-(OH)DOC has a definite, albeit weak antinatriuretic action in normal man, but whether or not this corticosteroid is capable of elevating the blood pressure in man remains to be shown.
