Spironolactone prevents Na+/H+ exchange enhancement in primary aldosteronism

The study was undertaken to determine the possible effect of an aldosterone antagonist, spironolactone (SP), on red blood cell sodium-hydrogen exchange (NHE) enhancement in primary aldosteronism (PA) and essential hypertension (EH). NHE was measured as the amiloride-inhibited fraction of H+ efflux (V max) from erythrocytes (pHi 6.40 +/- 0.05) into a Na+-containing medium (pHo 8.00 +/- 0.05). Subjects were 12 hypertensive patients with aldosterone-producing adrenal adenoma (six treated with 200 mg/day spironolactone for an least 5 days and six drug-free), 20 essential hypertensives (10 treated with the same regimen of spironolactone and 10 drug-free), and 20 healthy controls. Treatment with spironolactone decreased NHE in PA patients but did not change the mean NHE in essential hypertensives. It is concluded that SP may be useful to differentiate between elevated NHE in PA and essential hypertension.