Blood pressure and metabolic effects of 9-alpha-fluoro-hydrocortisone in sheep.

9 alphafluorohydrocortisone (9 alphaFF) is an analogue of hydrocortisone with both 'mineralocorticoid' and 'glucocorticoid' activity. 9 alphaFF was infused at 0.2, 0.63 and 2.0 mg/day for 5 days to intact conscious trained sheep. At high dose (0.63 and 2 mg/day) 9 alphaFF raises blood pressure in sheep, (mean arterial pressure rise 32 and 29 mm Hg respectively on the fifth day), lowers plasma [K], raises plasma [Na] and produces initial urinary sodium retention. At low dose (0.2 mg/day) blood pressure is raised (+16 mm Hg on day 5) but plasma and urinary electrolytes are unaltered. 9 alphaFF had no effect on water intake or urine output at any dose. In all animals withdrawal of 9 alphaFF was associated with a natriuresis. On the basis of its affinity for 'mineralocorticoid' and 'glucocorticoid' ovine renal receptors, 9 alphaFF at low dose may raise blood pressure by mechanisms not simply related to its 'glucocorticoid' and/or 'mineralocorticoid' action.