Tetrahydrobiopterin Supplementation Enhances Carotid Artery Compliance in Healthy Older Men: A Pilot Study

1] Department of Integrative Physiology, University of Colorado, Boulder, Colorado, USA [2] Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa, USA.
American Journal of Hypertension (Impact Factor: 2.85). 06/2012; 25(10):1050-4. DOI: 10.1038/ajh.2012.70
Source: PubMed


We performed a pilot study to test the hypothesis that acute oral ingestion of tetrahydrobiopterin (BH(4)), a key cofactor modulating vascular nitric oxide (NO) synthase activity, improves large elastic artery stiffness with aging in men.Methods
Healthy older (63 ± 2 years; n = 8) and young (age 25 ± 1 years; n = 6) men were studied 3 h after ingestion of BH(4) (10 mg·kg(-1) body weight) or placebo on separate days in a randomized, placebo-controlled, double-blind study.ResultsBaseline carotid artery compliance was 37% lower (0.17 ± 0.02 vs. 0.22 ± 0.02 mm/mm Hg·10(-1)) and β-stiffness was 42% higher (7.3 ± 1.1 vs. 4.2 ± 0.5 AU) in the older men (both P < 0.05). BH(4) ingestion markedly increased circulating BH(4) concentrations in both groups (17-19-fold, P < 0.05), but increased compliance (+39% to 0.23 ± 0.02 mm/mm Hg(.)10(-1), P < 0.01) and decreased β-stiffness index (-27% to 5.3 ± 0.7 AU, P < 0.01) only in the older men. BH(4) also reduced carotid systolic blood pressure (SBP) in the older men (P < 0.05).Conclusions
These preliminary results support the possibility that limited BH(4) bioavailability contributes to impaired carotid artery compliance in healthy older men. Further studies are needed to determine if increasing BH(4) bioavailability though oral BH(4) supplementation may have therapeutic efficacy for improving large elastic artery compliance and reducing central SBP with aging.American Journal of Hypertension 2012; doi:10.1038/ajh.2012.70.

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Available from: Allison E DeVan, Oct 07, 2014
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    • "Nevertheless, an effect of these confounders would be excluded by the stepwise multiple regression analysis (Table 4), showing an independent effect of age in the reduction of both NOx FSR and ASR. The reduced NO availability in aged people may be enhanced by antioxidants and by tetrahydrobiopterin, which prevent NOS uncoupling as well as NO use as a scavenger of oxygen radicals (26–28). Although the measurement of circulating antioxidants was beyond the purpose of our study, it would be interesting to test their effects in vivo on NOx kinetics. "
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