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Permanent link (DOI): https://doi.org/10.7939/R3154F126

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Effect of dietary nitrate on sympathetic vasoconstriction in resting and contracting skeletal muscle Open Access

Descriptions

Other title
Subject/Keyword
blood pressure
supplementation
vascular conductance
nitrate
sympathetic nervous system
vasoconstriction
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
de Vries, Christopher James
Supervisor and department
Dr. Darren DeLorey (Faculty of Physical Education and Recreation)
Examining committee member and department
Dr. Craig Steinback (Faculty of Physical Education and Recreation)
Dr. Margie Davenport (Faculty of Physical Education and Recreation)
Department
Physical Education and Recreation
Specialization

Date accepted
2015-09-30T11:54:03Z
Graduation date
2015-11
Degree
Master of Science
Degree level
Master's
Abstract
Dietary nitrate (NO3-) may increase nitric oxide (NO) bioavailability and alter the control of blood flow at rest and during exercise. This thesis investigated the effect of dietary NO3- supplementation on sympathetic mediated control of skeletal muscle blood flow in resting and contracting skeletal muscle. It was hypothesized that dietary NO3-: 1) would not alter plasma norepinephrine (NE) at rest, during exercise and in response to a sympatho-excitatory stimulus; 2) would attenuate blood pressure and sympathetic vasoconstrictor responsiveness at rest and during exercise and enhance functional sympatholysis. In a double-blind randomized crossover design 10 men (22±2.8 yrs.) performed a cold pressor test (CPT) at rest and during moderate- (30% WRmax) and heavy-intensity (60% WRmax) alternate-leg knee-extension exercise following consumption of either NO3--rich beetroot juice (~12.9 mMol NO3-) or a NO3--depleted placebo (~0.13 mMol NO3-). Venous blood was sampled before and after the consumption of beetroot juice and at rest and during exercise and each CPT. Heart rate and BP were measured continuously via ECG and Finometer, and mean blood velocity (MBV) was measured continuously via Doppler ultrasound. Leg Blood flow (LBF; ml·min−1) was calculated as MBV (cm·s−1)·π·vessel radius2·60. Femoral vascular conductance (FVC; L·min-1·mmHg-1) was calculated as LBF/MAP. Sympathetic vasoconstrictor responsiveness to a CPT was calculated by determining the magnitude of the decrease in FVC during the CPT at rest and during exercise. The magnitude of functional sympatholysis was calculated as FVC at rest (% change) – FVC during exercise (% change). Plasma [NO3-] was significantly elevated following consumption of NO3- rich beetroot juice, but not NO3--depleted placebo (NO3-: 9±4 a.u. ;Placebo: 2±1 a.u.). Dietary NO3- did not alter sympathetic vasoconstrictor responsiveness at rest (NO3-: -33±10 %; Placebo: -34±11 %), or during moderate- (NO3-: -17±10 %; Placebo: -21±10 %) or heavy-intensity (NO3-: -12±9 %; Placebo: -11±10 %) exercise. Sympatholysis was also not altered during moderate- (NO3-: -16±11 %; Placebo: -13±8 %) or heavy-intensity (NO3-: -21±11 %; Placebo: -23±6 %) exercise following NO3- supplementation. These data demonstrate that acute dietary NO3- supplementation did not alter the regulation of blood pressure at rest and in response to exercise and sympatho-excitation. In conclusion, acute dietary NO3- supplementation did not alter sympathetic nervous system mediated vascular control at rest or during exercise in healthy young men.
Language
English
DOI
doi:10.7939/R3154F126
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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