The effect of potassium loading and sodium depletion on DOC induced hypertension in sheep

This study examines the physiological effects of 11-deoxycorticosterone (DOC) at 2 rates of continuous iv infusion for 5 days in conscious sheep. DOC treatment, in sheep on Na and K intake 80 and 120 mmol/day respectively, increased mean arterial pressure (MAP) by 12 mmHg at 50 mg/day and by 10 mmHg at 5 mg/day. Both rates of infusion raised plasma [Na] and lowered plasma [K]. Urinary Na excretion fell on the first day of infusion. On cessation of infusion there was a natriuresis. A high K intake of approximately 800 mmol/day for 7 to 10 days prior to and during DOC (5 mg/day) treatment abolished the rise in blood pressure, the rise in plasma [Na], the initial Na retention and the post-DOC natriuresis. Plasma [K] rose with high K intake and fell with DOC. Na depletion prior to DOC infusion (5 mg/day) prevented the rise in MAP. Urinary Na excretion remained low and plasma [K] fell. This study shows that K loading abolishes DOC hypertension in sheep by a mechanism which may involve modification of the Na retaining effects of the steroid.