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Dietary Nitrate Supplementation Enhances Exercise Performance in Peripheral Arterial Disease.
MedLine Citation:
PMID:  21454745     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Peripheral Arterial Disease (PAD) results in a failure to adequately supply blood and O(2) to working tissues and presents as claudication pain during walking. Nitric oxide (NO) is essential for vascular health and function. Plasma nitrite (NO(2)(-)) is a marker of vascular NO production but may also be a protected circulating "source" that can be converted to NO during hypoxia, possibly aiding perfusion. We hypothesized that dietary supplementation of inorganic nitrate in the form of beetroot juice (BR) would increase plasma nitrite concentration [NO(2)(-)], increase exercise tolerance, and decrease gastrocnemius fractional O(2) extraction, compared to placebo (PL). This was a randomized open label cross-over study. At each visit subjects (n=8) underwent resting blood draws, followed by consumption of 500ml BR or PL and subsequent blood draws prior to, during and following a maximal cardiopulmonary exercise test (CPX). Gastrocnemius oxygenation during the CPX was measured by NIRS. There were no changes from rest for [NO(2)(-)] (152±72nM) following PL. BR increased plasma [NO(2)(-)] after 3hrs (943nM±826, p<0.01). Subjects walked 18% longer before the onset of claudication pain (183±84sec v 215±99sec, p≤0.01) and had a 17% longer peak walking time (467±223sec v 533±233sec, p≤0.05) following BR vs PL. Gastrocnemius tissue fractional O(2) extraction was lower during exercise following BR (7.3±6.2 v 10.4±6.1 AU, p≤0.01). Diastolic blood pressure was lower in the BR group at rest and during CPX testing (p≤0.05). These findings support the hypothesis that nitrite-related NO signaling increases peripheral tissue oxygenation in areas of hypoxia and increases exercise tolerance in PAD.
Authors:
Aarti A Kenjale; Katherine L Ham; Thomas Stabler; Jennifer L Robbins; Johanna L Johnson; Mitch Vanbruggen; Grayson Privette; Eunji Yim; William E Kraus; Jason David Allen
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-31
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  -     ISSN:  1522-1601     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-4-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1Duke University Medical Center.
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