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Updated: Jul 11, 2026

Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Effect of acute changes in oxygen tension on flow-mediated dilation. Relation to cardivascular risk
Ole Frøbert1, Pernille Holmager, Ken Michael Jensen
1Center for Cardiovascular Research, Department of Cardiology, Aalborg Hospital, and Department of Pharmacology, University of Aarhus, Aalborg, Denmark. frobert@dadlnet.dk
Objective:
Oxygen-dependent changes in vascular diameters may be detrimental when the endothelium is dysfunctional.
Design:
Endothelial responsiveness was evaluated by brachial ultrasound and flow-mediated/nitroglycerin-mediated dilation (FMD/NMD). FMD/NMD was investigated in males with increased risk of cardiovascular disease (mean age 44+/-2 years, n=10) and matched controls without risk factors (44+/-2 years, n=10). FMD/NMD was assessed during normoxia (21% O2, 79% N2), while inhaling hypoxic gas (12.5% O2, FMDHyp/NMD), and 100% O2 supplementation (FMDO2/NMD). In a second study we addressed the effect of lipid lowering. Twenty persons with cardiovascular risk (mean age 50+/-2 years) were treated with atorvastatin (80 mg/day) and FMD/NMD was measured during normoxia, hypoxia and oxygen supplementation before, after 1 day and 3 months.
Results:
Oxygen supplementation evoked vasoconstriction, while FMDHyp/NMD was reduced compared to FMD/NMD. Atorvastatin significantly lowered total cholesterol, LDL cholesterol, and ADMA after 1 day of treatment, while triglycerides, ApoB and hsCRP were lowered after 3 months. Atorvastatin did not change FMD/NMD irrespective of oxygen tension.
Conclusion:
Irrespective of risk factors or atorvastatin, hypoxia reduced endothelial vasodilation while oxygen supplementation evoked vasoconstriction.
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