title: Acute, quercetin-induced reductions in blood pressure in hypertensive individuals are not secondary to lower plasma angiotensin-converting enzyme activity or endothelin-1: nitric oxide.
abstract: Quercetin (Q) reduces blood pressure (BP) in hypertensive individuals, but the mechanism is unknown. We hypothesized that acute Q aglycone administration reduces BP in hypertensive men by decreasing angiotensin-converting enzyme (ACE) activity and/or by lowering the ratio of circulating endothelin-1 (ET-1) to nitric oxide and that these alterations will improve endothelial function. Using a double-blind, placebo-controlled, crossover design Q or placebo (P) was administered to normotensive men (n = 5; 24 ± 3 years; 24 ± 4 kg/m(2)) and stage 1 hypertensive men (n = 12; 41 ± 12 years; 29 ± 5 kg/m(2)). As anticipated, ingesting 1095 mg Q did not affect BP in normotensive men but resulted in maximal plasma Q (2.3 ± 1.8 μmol/L) at approximately 10 hours, with Q returning to baseline concentrations (0.4 ± 0.08 μmol/L) by approximately 17 hours. Results from this study provided rationale for determining end-points of interest in stage 1 hypertensive men 10 hours after ingesting Q or P. In stage 1 hypertensive individuals, plasma Q increased(0.6 ± 0.4 vs. 0.05 ± 0.02 μmol/L), and mean BP decreased (103 ± 7 vs 108 ± 7 mm Hg; both P < .05) 10 hours after Q vs P, respectively. Plasma ACE activity (16 ± 10 vs 18 ± 10 U/L), ET-1 (1.6 ± 0.9 vs 1.6 ± 0.8 pg/ml), nitrites (57.0 ± 3.0 vs 56.7 ± 2.6 μmol/L), and brachial artery flow-mediated dilation (6.2 ± 2.9 vs. 6.3 ± 3.2%) were unaffected by Q. A single dose of Q aglycone reduces BP in hypertensive men through a mechanism that is independent of changes in ACE activity, ET-1, or nitric oxide bioavailability and without affecting vascular reactivity.
authors.affiliation: Department of Exercise and Sports Science, College of Health, University of Utah, Salt Lake City, UT 84132, USA.
authors.forename: Abigail
authors.initials: A
authors.lastname: Larson
authors.forename: Melissa A H
authors.initials: MA
authors.lastname: Witman
authors.forename: Yi
authors.initials: Y
authors.lastname: Guo
authors.forename: Stephen
authors.initials: S
authors.lastname: Ives
authors.forename: Russell S
authors.initials: RS
authors.lastname: Richardson
authors.forename: Richard S
authors.initials: RS
authors.lastname: Bruno
authors.forename: Thunder
authors.initials: T
authors.lastname: Jalili
authors.forename: J David
authors.initials: JD
authors.lastname: Symons
mesh_terms: D000328:Adult; D062186:Arterial Pressure / Q000187:drug effects*; D001916:Brachial Artery; D018592:Cross-Over Studies; D004311:Double-Blind Method; D019332:Endothelin-1 / Q000097:blood*; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D009569:Nitric Oxide / Q000097:blood*; D009573:Nitrites / Q000097:blood; D007703:Peptidyl-Dipeptidase A / Q000097:blood*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D011794:Quercetin / Q000494:pharmacology* / Q000627:therapeutic use; D014664:Vasodilation; D055815:Young Adult
chemical_list: D019332:Endothelin-1; D009573:Nitrites; D010936:Plant Extracts; D009569:Nitric Oxide; D011794:Quercetin; D007703:Peptidyl-Dipeptidase A