J Am Coll Cardiol. 2013 Jan 22;61(3):335-43.
Dietary sodium restriction reverses vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure.
Jablonski KL, Racine ML, Geolfos CJ, Gates PE, Chonchol M, McQueen MB, Seals DR.
Source
Department of Integrative Physiology, University of Colorado, Boulder, Colorado
80309, USA.
Abstract
OBJECTIVES:
This study sought to determine the efficacy of dietary sodium restriction (DSR)
for improving vascular endothelial dysfunction in middle-aged/older adults with
moderately elevated systolic blood pressure (SBP) (130-159 mm Hg) and the
associated physiological mechanisms.
BACKGROUND:
Vascular endothelial dysfunction develops with advancing age and elevated SBP,
contributing to increased cardiovascular risk. DSR lowers BP, but its effect on
vascular endothelial function and mechanisms involved are unknown.
METHODS:
Seventeen subjects (11 men and 6 women; mean age, 62 ± 7 years) completed a,
randomized crossover study of 4 weeks of both low (DSR) and normal sodium intake.
Vascular endothelial function (endothelium-dependent dilation; EDD), nitric
oxide (NO)/tetrahydrobiopterin (BH(4)) bioavailability, and oxidative
stress-associated mechanisms were assessed following each condition.
RESULTS:
Urinary sodium excretion was reduced by ? 50% (to 70 ± 30 mmol/day), and conduit
(brachial artery flow-mediated dilation [FMD(BA)]) and resistance (forearm blood
flow responses to acetylcholine [FBF(ACh)]) artery EDD were 68% and 42% (peak
FBF(ACh)) higher following DSR (p < 0.005). Low sodium markedly enhanced
NO-mediated EDD (greater ?FBF(ACh) with endothelial NO synthase inhibition)
without changing endothelial NO synthase expression/activation (Ser 1177
phosphorylation), restored BH(4) bioactivity (less ?FMD(BA) with acute BH(4)),
abolished tonic superoxide suppression of EDD (less ?FMD(BA) and ?FBF(ACh) with
ascorbic acid infusion), and increased circulating superoxide dismutase activity
(all p < 0.05). These effects were independent of ?SBP. Other subject
characteristics/dietary factors and endothelium-independent dilation were
unchanged.
CONCLUSIONS:
DSR largely reversed both macro- and microvascular endothelial dysfunction by
enhancing NO and BH(4) bioavailability and reducing oxidative stress. Our
findings support the emerging concept that DSR induces "vascular protection"
beyond that attributable to its BP-lowering effects.
Copyright © 2013 American College of Cardiology Foundation. Published by
Elsevier Inc. All rights reserved.
PMID: 23141486 [PubMed - indexed for MEDLINE]