Effects of adrenomedullin on angiotensin II stimulated atrial natriuretic peptide and arginine vasopressin secretion in healthy humans

Aims Adrenomedullin is a newly described peptide that has widespread tissue distribution. Its presence in cardiovascular (including vascular endotheli al cells, smooth muscle cells, and cardiac atria and ventricles) and renal tissues, together with its vasodilatory and natriuretic properties, suggest a role in blood pressure regulation and fluid and electrolyte balance. Methods Nine normal volunteers were studied to determine whether or not adr enomedullin influenced plasma atrial natriuretic peptide and arginine vasop ressin concentrations during systemic angiotensin II infusion. Results A significant (P = 0.02) augmentation of atrial natriuretic peptide concentrations, but no suppression of arginine vasopressin concentrations, was found with coinfusion of adrenomedullin and angiotensin II when compar ed with vehicle and angiotensin II. Conclusions Despite its vasodilator and natriuretic action, adrenomedullin significantly augmented angiotensin II-stimulated plasma atrial natriuretic peptide concentrations in healthy humans. This provides further evidence o f a synergistic interaction between adrenomedullin and atrial natriuretic p eptide and suggests that adrenomedullin may have a role in fluid and electr olyte balance and blood pressure regulation.