Prolonged administration of human atrial natriuretic peptide in healthy men. Reduced aldosteronotropic effect of angiotensin II.

The effect of angiotensin II (5, 10, 20 ng/kg/min) on blood pressure and on the plasma concentrations of aldosterone was studied in six healthy men with and without the concomitant administration of synthetic human atrial natriuretic peptide given 1) as an i.v. bolus of 25 micrograms followed by a 6-hour infusion of 25 micrograms/hr or 2) as an i.v. bolus of 175 micrograms followed by a 6-hour infusion of 100 micrograms/hr. The pressor effect of angiotensin II (i.e., the rise of mean blood pressure above individual basal levels) remained unchanged during the administration of both doses of human atrial natriuretic peptide. The angiotensin II-induced rise in plasma concentrations of aldosterone in terms of absolute values) was reduced by human atrial natriuretic peptide during both trials. The rise in plasma concentrations of aldosterone above individual basal concentrations was also reduced during the administration of human atrial natriuretic peptide, although this effect was only marginal during the low dose experiment. These effects of human atrial natriuretic peptide support the contention that its therapeutic impact in hypertensive patients might be mediated in part by a reduction of high aldosterone concentrations.