Key result
L-NMMA infusion increases plasma renin activity during salt depletion without altering angiotensin vascular responses.
Why the study?
Animal studies suggest nitric oxide regulates the renin-angiotensin-aldosterone system, but its effects in humans vary and require assessment.
Does L-NMMA infusion alter plasma renin activity and angiotensin responses in healthy humans?
RCT
Does L-NMMA infusion alter plasma renin activity and angiotensin responses in healthy humans?
Nitric oxide regulates the renin response to salt depletion in healthy humans but does not affect vascular or aldosterone responses to angiotensin.
Answers are grounded in this paper and cite their sources.
NO selectively regulates renin during salt depletion without altering angiotensin responses; hypothesis-generating for volume regulation but should not change practice.
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 measure ments 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 angio tensin I and II were given with and without L-NMMA, and forearm blood flow was mea sured to assess the effects of nitric oxide on vascular responses to the angiotensin peptides. During salt depletion, L-NMMA infusion resulted in significantly higher plasma renin activ ity. 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 healthy humans but does not affect responses to angiotensin.
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Davidson et al. (1999) conducted an RCT in Healthy humans. L-nitrosomonomethyl arginine (L-NMMA) vs. Placebo or no L-NMMA was evaluated on Plasma renin activity and systemic/forearm pressor or aldosterone responses. L-NMMA infusion significantly increased plasma renin activity during salt depletion, but had no effect on systemic pressor, forearm pressor, or aldosterone responses to angiotensin in healthy humans.
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