Effects of enalaprilic acid on sodium excretion and renal hemodynamics in essential hypertension.

The effects of MK 422 (enalaprilic acid) on renal function and electrolyte excretion were assessed in 14 patients with essential hypertension on a sodium intake of 100 mmol/day. Injection of MK 422 led to a prompt fall in blood pressure (p less than 0.01). Effective renal plasma flow increased by 9 +/- 4% (p less than 0.01) within 1 hour, an increase that persisted for a least 5 hours. Glomerular filtration rate did not change, so filtration fraction decreased by 6 +/- 2% (p less than 0.01). Sodium excretion increased with a maximum of 61 +/- 17% (p less than 0.01) after 5 hours, and potassium excretion fell (p less than 0.01). The log of the initial plasma renin activity correlated with the changes in blood pressure (r = 0.59, p less than 0.05) in effective renal plasma flow (r = 0.59, p less than 0.05) and in sodium excretion (r = 0.65, p less than 0.01). All the renal effects of MK 422 could be reversed by infusion with angiotensin II.