Retrograde Flow and Shear Rate Acutely Impair Endothelial Function in Humans

• Published in: Hypertension (Dallas, Tex. 1979) Vol. 53; no. 6; pp. 986 - 992
• Main Authors: Thijssen, Dick H.J, Dawson, Ellen A, Tinken, Toni M, Cable, N Timothy, Green, Daniel J
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.06.2009; Lippincott Williams & Wilkins
• Subjects: Adult; Analysis of Variance; Area Under Curve; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Flow Velocity - physiology; Blood Pressure Determination - methods; Brachial Artery - physiology; Cardiology. Vascular system; Endothelium, Vascular - physiopathology; Experimental diseases; Forearm - blood supply; Humans; Male; Medical sciences; Muscle Contraction - physiology; Muscle, Smooth, Vascular - physiology; Probability; Reference Values; Risk Factors; Sampling Studies; Sensitivity and Specificity; Shear Strength - physiology; Vasoconstriction - physiology; Vasodilation - physiology; Young Adult; Doppler ultrasound study; Human; Hypertension; endothelial function; Shear; retrograde shear stress; Shear stress; Cardiovascular disease; oscillatory; shear stress pattern; echo Doppler
• DOI: 10.1161/HYPERTENSIONAHA.109.131508
• ISSN: 0194-911X

Changes in arterial shear stress induce functional and structural vasculature adaptations. Recent studies indicate that substantial retrograde flow and shear can occur through human conduit arteries. In animals, retrograde shear is associated with atherogenic effects. The aim of this study was to examine the impact of incremental levels of retrograde shear on endothelial function in vivo. On 3 separate days, we examined bilateral brachial artery flow-mediated dilation, an index of NO-mediated endothelial function, in healthy men (24±3 years) before and after a 30-minute intervention consisting of cuff inflation to 25, 50, or 75 mm Hg. Cuff inflations resulted in “dose”-dependent increases in retrograde shear rate, compared with the noncuffed arm, within subjects (P<0.001). Flow-mediated dilation in the cuffed arm did not change in response to the 25-mm Hg stimulus but decreased significantly after both the 50- and 75-mm Hg interventions (P<0.05). The decrease in flow-mediated dilation after the 75-mm Hg intervention was significantly larger than that observed after a 50-mm Hg intervention (P=0.03). In the noncuffed arm, no changes in shear rate or flow-mediated dilation were observed. These results demonstrate that an increase in retrograde shear rate induces a dose-dependent attenuation of endothelial function in humans. This finding contributes to our understanding regarding the possible detrimental effects of retrograde shear rate in vivo.