Effect of spironolactone on urinary excretion of immunoreactive prostaglandin E in essential hypertension and primary aldosteronism.

Abstract

To determine the effect of aldosterone antagonist on renal prostaglandin E synthesis, the rate of urinary excretion of immunoreactive prostaglandin E was measured radioimmunologically before and during the oral administration of an aldosterone antagonist, spironolactone, in 5 patients with essential hypertension, 3 with primary aldosteronism and 2 with postoperative primary aldosteronism. Spironolactone was administered at an oral dose of 25 mg 4 times daily for about 1 week. In the control state, the rates of urinary prostaglandin E excretion ranged from 151 ng/day to 4,527 ng/day in essential hypertension. The rates were not augmented in primary aldosteronism but decreased after the removal of an aldosterone producing adenoma. No obvious relationship was observed between plasma aldosterone concentration and the rate of urinary prostaglandin E excretion. On the first day of spironolactone administration, the excretion rates of urinary prostaglandin E were markedly increased independently of basal plasma aldosterone level in all cases except one case of essential hypertension. Urinary prostaglandin E excretion was increased with the concominant increase of urinary Na/K ratio in essential hypertension and primary aldosteronism. After the second day, the augmented urinary prostaglandin E excretion was decreased and the changes of urinary prostaglandin E excretion varied from case to case. These results suggest that synthesis of renal prostaglandin E is not mainly regulated by aldosterone in essential hypertension and primary aldosteronism.