l-NMMA Increases Arteriolar But Not Venous Tone in Humans
- 1 January 1991
- journal article
- research article
- Published by Wolters Kluwer Health in Journal of Cardiovascular Pharmacology
- Vol. 17 (Supplement) , S182-S185
- https://doi.org/10.1097/00005344-199117003-00034
Abstract
Summary: l-NMMA increases arteriolar but not venous tone in humans but the mechanism underlying this arteriovenous difference is unclear. One possibility is that the basal sympathetic tone in arterioles stimulates basal nitric oxide (NO) release, or that NO interferes with sympathetic neurotransmission. In this study, we have investigated the effects of local infusions of NG-monomethyl-l-arginine (l-NMMA) on the norepinephrine dose-response and the response to sympathetically mediated venoconstriction in human hand veins in vivo. The results show that l-NMMA has no effect on sympathetic venoconstriction or the constriction produced by infusion of norepinephrine. The lack of effect of l-NMMA on resting venous tone cannot be explained by the absence of basal norepinephrine release from sympathetic nerves. We can find no evidence for interaction between NO and sympathetic nerves in these vessels.Keywords
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