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Updated: May 10, 2026
08:42
Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Does brachial artery flow-mediated vasodilation provide a bioassay for NO?
D Walter Wray1, Melissa A H Witman, Stephen J Ives
1Division of Geriatrics, Department of Internal Medicine, University of Utah, VAMC SLC, GRECC 182, Bldg 2 Rm 1C03, 500 Foothill Dr, Salt Lake City, UT 84148, USA. walter.wray@hsc.utah.edu
Hypertension (Dallas, Tex. : 1979)
|June 19, 2013
Summary
Nitric oxide (NO) plays a role in brachial artery flow-mediated vasodilation (FMD) but may not be obligatory in healthy young adults. This challenges FMD
Area of Science:
- Cardiovascular Physiology
- Vascular Biology
- Nitric Oxide Research
Background:
- Flow-mediated vasodilation (FMD) assesses endothelial function.
- Nitric oxide (NO) is a key mediator of vasodilation.
- The necessity of NO for brachial artery FMD in healthy young adults requires further definition.
Purpose of the Study:
- To investigate the role of NO in brachial artery FMD in young, healthy humans.
- To determine if NO is obligatory for FMD using an endothelial NO synthase inhibitor.
- To evaluate the sensitivity of FMD for assessing NO bioavailability.
Main Methods:
- Ultrasound Doppler was used to measure brachial artery velocity and diameter in 8 healthy volunteers.
- Forearm circulatory occlusion was performed with and without intra-arterial infusion of N(G)-monomethyl-L-arginine (L-NMMA).
- FMD was assessed with occlusion cuffs placed distally and proximally to the measurement site.
Main Results:
- L-NMMA significantly reduced FMD in the distal cuff trial but not in the proximal cuff trial.
- When adjusted for shear stimulus, L-NMMA had no significant effect on FMD in either cuff position.
- These findings suggest NO is not obligatory for brachial artery FMD in this population.
Conclusions:
- The results challenge the assertion that nitric oxide is essential for brachial artery FMD.
- The study questions the sensitivity of FMD for noninvasive determination of NO bioavailability in young, healthy individuals.
- Further research is needed to fully elucidate the role of NO in vascular function assessment.
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