Nitric Oxide Regulates Renin Release During Salt Depletion but Does Not Alter Angiotensin Responses in Normal Humans.
BACKGROUND: Animal studies suggest that nitric oxide regulates the renin-angiotensin-aldosterone system, but this effect varies among species. The effects of nitric oxide on the renin-angiotensin-aldosterone system in humans were assessed using L-nitrosomonomethyl-arginine (L-NMMA) an antagonist of nitric oxide synthase. METHODS AND RESULTS: In experiment 1, subjects were pretreated with furosemide to induce salt depletion and received placebo-controlled infusions of L-NMMA followed by measurements of plasma renin activity. In experiment 2, subjects were given angiotensin I and II intravenously with and without L-NMMA to assess the effects of nitric oxide on systemic pressor and aldosterone responses. In experiment 3, brachial arterial infusions of angiotensin I and II were given with and without L-NMMA, and the forearm blood flow was measured to assess the effects of nitric oxide on vascular responses to the angiotensin peptides. During salt depletion, L-NMMA infusion resulted in significant higher plasma renin activity. L-NMMA had no effect on systemic or forearm pressor responses or aldosterone responses to angiotensin I and II infusions. CONCLUSIONS: These results indicate that nitric oxide regulates the renin response to salt depletion in health humans but does not affect responses to angiotensin.
Davidson
NC
Department of Clinical Pharmacology, Ninewells Hospital and Medical School, Dundee, United Kingdom
Struthers
AD