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Updated: Aug 8, 2026

Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research
Published on: October 22, 2014
Abnormal responses to endothelial agonists in Raynaud's phenomenon and scleroderma
R R Freedman1, R Girgis, M D Mayes
1Department of Psychiatry, Wayne State University School of Medicine, Detroit, Michigan, USA. aa2613@wayne.edu
Objective:
To further specify the site of vascular dysfunction in patients with Raynaud's phenomenon (RP) and scleroderma.
Methods:
Ten patients with RP and scleroderma and 11 healthy control subjects received brachial artery infusions of sodium nitroprusside, an endothelium independent vasodilator, bradykinin, and substance P while bilateral finger blood flow was measured with venous occlusion plethysmography.
Results:
Both groups showed vasodilation to sodium nitroprusside. However, in response to the endothelium dependent compounds bradykinin and substance P, the controls showed vasodilation, whereas the patients showed vasoconstriction.
Conclusion:
The vascular defect in RP and scleroderma does not lie at the site of the muscarinic receptor, but possibly in a distal signaling mechanism.
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