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dc.contributor.advisorDinenno, Frank A.
dc.contributor.authorSimpson, Carrie Beth
dc.contributor.committeememberEarley, Scott
dc.contributor.committeememberBell, Christopher
dc.date.accessioned2007-01-03T06:40:19Z
dc.date.available2007-01-03T06:40:19Z
dc.date.issued2009
dc.descriptionDepartment Head: Richard Gay Israel.
dc.description2009 Summer.
dc.descriptionIncludes bibliographical references (pages 40-45).
dc.description.abstractAge-related increases in oxidative stress are known to impair endothelium dependent vasodilation in older healthy humans. As a result, many researchers have speculated that endothelial dysfunction contributes to impaired muscle blood flow and vascular control during exercise. Further, elevations in oxidative stress and subsequent endothelial dysfunction could possibly explain our recent observations of impaired contraction-induced rapid vasodilation in older adults. Therefore, we directly tested the hypothesis that acute ascorbic acid administration would augment (1) rapid vasodilation in response to single muscle contractions as well as (2) the hyperemic response to sustained rhythmic contractions in older healthy humans, and that this would be due to improved endothelium-dependent vasodilation. In 14 young (22±1 yrs) and 14 healthy older men and women (65±2 yrs), we measured forearm blood flow (FBF; Doppler ultrasound) and calculated vascular conductance (FVC) responses to single, 1 second dynamic contractions at 10, 20, and 40% maximum voluntary contraction (MVC) before and after intra-arterial administration of ascorbic acid (AA). We also measured these variables during rhythmic handgrip exercise at 10% maximum voluntary contraction. After 5 minutes of steady-state exercise with saline, ascorbic acid (AA) was infused via brachial artery catheter for 10 minutes during continued exercise. For single contractions, prior to AA peak vasodilator responses to all contraction intensities were impaired ~35-50% in older adults (P<0.05), as were the immediate (1st cardiac cycle post contraction) vasodilator responses at 20 and 40% MVC (~50%; P<0.05). In contrast to our hypothesis, AA did not influence contraction-induced rapid vasodilation in either group (all NS). Regarding rhythmic handgrip exercise, FBF (~28%) and FVC (~31%) were lower in older vs young adults (P=0.06 and P<0.05) prior to AA. In young adults, AA administration did not significantly influence FBF and FVC, whereas FBF and FVC increased 30±4% in older adults at end exercise (P<0.05). AA did not influence vasodilator responses to sodium nitroprusside in either group, but significantly improved vasodilation to acetylcholine in older adults only (P<0.05). We conclude that endothelial dysfunction is not the primary mechanism underlying impaired contraction-induced rapid vasodilation with human aging; however acute AA administration increases muscle blood flow during dynamic exercise in older adults, which is likely due to an improvement in endothelium dependent vasodilation.
dc.format.mediummasters theses
dc.identifier2009_summer_Simpson.pdf
dc.identifierETDF2009100003HAES
dc.identifier.urihttp://hdl.handle.net/10217/23287
dc.languageEnglish
dc.publisherColorado State University. Libraries
dc.relationCatalog record number (MMS ID): 991012198789703361
dc.relationQP772.A8.S55 2009
dc.relation.ispartof2000-2019 - CSU Theses and Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectacute AA administration
dc.subjectacute ascorbic acid administration
dc.subjectoxidative stress
dc.subjectendothelial dysfunction
dc.subjectcontraction-induced rapid vasodilation
dc.subjectolder adults
dc.subjectaging
dc.subjectexercise hyperaemia
dc.subject.lcshVitamin C -- Physiological effect
dc.subject.lcshOlder people -- Exercise -- Physiological aspects
dc.subject.lcshOxidative stress
dc.subject.lcshVascular endothelium
dc.subject.lcshBlood-vessels -- Dilatation
dc.titleAcute ascorbic acid administration improves exercise hyperemia during rhythmic but not single contractions in aging humans
dc.typeText
dcterms.rights.dplaThe copyright and related rights status of this item has not been evaluated (https://rightsstatements.org/vocab/CNE/1.0/). Please refer to the organization that has made the Item available for more information.
thesis.degree.disciplineHealth and Exercise Science
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)


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