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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

Larson A, Witman MA, Guo Y, Ives S, Richardson RS, Bruno RS, Jalili T, Symons JD

Nutrition research (New York, N.Y.), 2012

12 participants

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…

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Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 12 participants or records.

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