Tetrahydrobiopterin restores endothelial function in long-term smokers
OBJECTIVES We sought to test whether tetrahydrobiopterin (BH4) supplementation improves nitric oxide (NO) bioactivity in smokers. BACKGROUND In smokers, endothelium-derived NO bioactivity is impaired. BH4 is an essential cofactor of NO synthase, and its deficiency decreases NO bioactivity. METHODS S...
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Published in | Journal of the American College of Cardiology Vol. 35; no. 1; pp. 71 - 75 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
New York, NY
Elsevier Inc
01.01.2000
Elsevier Science |
Subjects | |
Online Access | Get full text |
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Summary: | OBJECTIVES
We sought to test whether tetrahydrobiopterin (BH4) supplementation improves nitric oxide (NO) bioactivity in smokers.
BACKGROUND
In smokers, endothelium-derived NO bioactivity is impaired. BH4 is an essential cofactor of NO synthase, and its deficiency decreases NO bioactivity.
METHODS
Sapropterin hydrochloride, an active analogue of BH4 (2 mg/kg body weight), was administered orally to healthy male smokers and age-matched nonsmokers. Before and 3 and 24 h after sapropterin, we measured plasma levels of BH4 and examined flow-mediated vasodilation (FMV) of the brachial artery by high resolution ultrasonography, a noninvasive test of endothelial function.
RESULTS
Basal plasma levels of BH4 were not different between smokers and nonsmokers. Sapropterin administration increased plasma levels of BH4 by threefold at 3 h, which returned to the baseline at 24 h. Before sapropterin, FMV was significantly smaller in smokers (p = 0.0002). Sapropterin significantly augmented endothelium-dependent vasodilation in smokers, but did not affect it in nonsmokers (p = 0.001 by analysis of variance [ANOVA]). Coadministration of NG-monomethyl-l-arginine (L-NMMA), an NO synthase inhibitor (20 μmol), into the brachial artery completely abolished the vasodilatory effects of sapropterin (p = 0.002 by ANOVA). Endothelium-independent vasodilation by glyceryl trinitrate was not different between smokers and nonsmokers and was not altered by BH4.
CONCLUSIONS
We demonstrated that BH4 supplementation improved bioactivity of endothelium-derived NO in smokers. These observations strongly suggest that decreased NO-dependent vasodilation in smokers could be related to reduced bioactivity of BH4. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0735-1097 1558-3597 |
DOI: | 10.1016/S0735-1097(99)00523-9 |