Brachial Artery Flow-mediated Dilation Following Exercise with Augmented Oscillatory and Retrograde Shear Rate

Arterial endothelial function is acutely and chronically regulated by blood flow-associated shear stress. An acute intervention employing modest forearm cuff occlusion to simultaneously increase retrograde and decrease mean brachial artery shear rate for 30 min evokes transient impairments in flow-mediated dilation (FMD). However, the independent influence of the low mean versus the retrograde shear stress components is unclear. Healthy young adults [ n = 24 (12 women, 12 men); 22 ± 2 yr, body mass index = 25 ± 2 kg/m2 (mean ± SD)] completed three laboratory visits within 1 wk. Visits consisted of 45 min of supine rest followed by a brachial artery FMD test (duplex ultrasound) before and after a 30-min intervention: control (shear rate unchanged), cuff (mean shear rate decreased, retrograde shear rate increased), or arterial compression (mean shear rate decreased, no increase in retrograde shear rate). The mean shear rate on the compression visit was targeted to match that achieved on the cuff visit. Cuff and compression trials decreased mean shear rate to a similar extent (cuff: 43 ± 22 s−1, compression: 43 ± 21 s−1; P = 0.850) compared with control (65 ± 21 s−1; both P < 0.001), with the retrograde component elevated only in the former (cuff: −83 ± 30 s−1, compression: −7 ± 5 s−1; P < 0.001). FMD decreased by 29 ± 30% ( P < 0.001) after the cuff intervention and 32 ± 24% ( P < 0.001) after the compression trial but was unchanged on the control visit (−0.3 ± 18%; P = 0.754). This was not altered by accounting for the shear rate stimulus. An increased retrograde shear stress does not appear to be obligatory for the transient reduction in FMD achieved after a 30-min exposure to low mean shear stress. These findings provide novel mechanistic insight on the regulation of endothelial function in vivo. NEW & NOTEWORTHY Low mean and retrograde shear stress are considered atherogenic; however, their relative contribution to the acute regulation of endothelial function in humans is unclear. Matched reductions in mean shear stress (30 min), with and without increases in retrograde shear stress, elicited equivalent reductions in flow-mediated dilation in men and women. These findings afford novel insight regarding the shear stress components governing the acute (dys)regulation of conduit artery endothelial function in vivo.

Download Full-text

The Influence of Muscle Mass on Shear Rate and Brachial Artery Flow Mediated Dilation in the Elderly

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000274691.53179.4c ◽

2007 ◽

Vol 39 (Supplement) ◽

pp. S428

Author(s):

Devon A. Dobrosielski ◽

Arturo A. Arce Esquivel ◽

Kim Landry ◽

Eric Ravussin ◽

Michael A. Welsch

Keyword(s):

Shear Rate ◽

Muscle Mass ◽

Brachial Artery ◽

The Elderly ◽

Flow Mediated Dilation ◽

Artery Flow

Download Full-text

Fluctuation in shear rate, with unaltered mean shear rate, improves brachial artery flow-mediated dilation in healthy, young men

Journal of Applied Physiology ◽

10.1152/japplphysiol.00009.2019 ◽

2019 ◽

Vol 126 (6) ◽

pp. 1687-1693 ◽

Cited By ~ 4

Author(s):

Sophie M. Holder ◽

Ellen A. Dawson ◽

Áine Brislane ◽

Jonny Hisdal ◽

Daniel J. Green ◽

...

Keyword(s):

Shear Stress ◽

Shear Rate ◽

Endothelial Function ◽

Brachial Artery ◽

Negative Pressure ◽

Mixed Model ◽

Linear Mixed Model ◽

Flow Mediated Dilation ◽

Conduit Artery ◽

Artery Flow

Increase in mean shear stress represents an important and potent hemodynamic stimulus to improve conduit artery endothelial function in humans. No previous study has examined whether fluctuations in shear rate patterns, without altering mean shear stress, impacts conduit artery endothelial function. This study examined the hypothesis that 30-min exposure to fluctuations in shear rate patterns, in the presence of unaltered mean shear rate, improves brachial artery flow-mediated dilation. Fifteen healthy men (27.3 ± 5.0 yr) completed the study. Bilateral brachial artery flow-mediated dilation was assessed before and after unilateral exposure to 30 min of intermittent negative pressure (10 s, −40mmHg; 7 s, 0 mmHg) to induce fluctuation in shear rate, while the contralateral arm was exposed to a resting period. Negative pressure significantly increased shear rate, followed by a decrease in shear rate upon pressure release (both P < 0.001). Across the 30-min intervention, mean shear rate was not different compared with baseline ( P = 0.458). A linear mixed model revealed a significant effect of time observed for flow-mediated dilation ( P = 0.029), with exploratory post hoc analysis showing an increase in the intervention arm (∆FMD +2.0%, P = 0.008), but not in the contralateral control arm (∆FMD +0.5%, P = 0.664). However, there was no effect for arm ( P = 0.619) or interaction effect ( P = 0.096). In conclusion, we found that fluctuations in shear patterns, with unaltered mean shear, improves brachial artery flow-mediated dilation. These novel data suggest that fluctuations in shear pattern, even in the absence of altered mean shear, represent a stimulus to acute change in endothelial function in healthy individuals. NEW & NOTEWORTHY Intermittent negative pressure applied to the forearm induced significant fluctuations in antegrade and retrograde shear rate, while mean shear was preserved relative to baseline. Our exploratory study revealed that brachial artery flow-mediated dilation was significantly improved following 30-min exposure to intermittent negative pressure. Fluctuations in blood flow or shear rate, with unaltered mean shear, may have important implications for vascular health; however, further research is required to identify the underlying mechanisms and potential long-term health benefits.

Download Full-text

Vitamin C prevents the acute decline of flow-mediated dilation after altered shear rate patterns

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2012-0169 ◽

2013 ◽

Vol 38 (3) ◽

pp. 268-274 ◽

Cited By ~ 26

Author(s):

Blair D. Johnson ◽

Kieren J. Mather ◽

Sean C. Newcomer ◽

Timothy D. Mickleborough ◽

Janet P. Wallace

Keyword(s):

Oxidative Stress ◽

Shear Rate ◽

Vitamin C ◽

Flow Mediated Dilation ◽

Double Blind ◽

Vitamin C Supplementation ◽

Artery Flow ◽

Blind Crossover Study ◽

Double Blind Crossover Study ◽

Retrograde Shear

Oscillatory and retrograde shear rate (SR) impairs endothelial function, potentially through shear-induced oxidative stress. We tested the hypothesis that acute vitamin C supplementation would prevent the attenuation of brachial artery flow-mediated dilation (FMD) after a period of augmented oscillatory and retrograde SR. Twelve healthy men (aged 26 ± 3 years) participated in two 30-min study visits in which one arm was subjected to increased oscillatory and retrograde SR, using 60 mm Hg of forearm cuff compression, and the contralateral arm served as the control. Subjects ingested capsules containing either placebo (sucrose) or vitamin C at 90 and 120 min (1000 mg total vitamin C) prior to cuff compression periods in a randomized placebo-controlled double-blind crossover study. Oscillatory and retrograde SR in the cuffed arms increased during the compression periods in the placebo and vitamin C study visits (p < 0.01 for both), with no difference between studies (p > 0.05). Antegrade SR remained unchanged throughout the compression periods (p > 0.05), and mean SR was lower in the cuffed arm than in the control arm for both study visits (p < 0.05). FMD decreased after cuff compression in the placebo cuffed arm (precompression vs. postcompression, 5.2% ± 1.4% vs. 3.5% ± 1.4%; p < 0.05), but remained unchanged after vitamin C therapy in the cuffed arm (precompression vs. postcompression, 5.3% ± 2.4% vs. 5.7% ± 2.6%; p > 0.05). No FMD changes were observed in the control arm for either study visit (p > 0.05). These data demonstrate that acute vitamin C supplementation prevents the attenuation of FMD due to altered SR patterns, suggesting that oxidative stress contributes to the oscillatory and retrograde SR-induced impairment of FMD.

Download Full-text

Aerobic exercise acutely prevents the endothelial dysfunction induced by mental stress among subjects with metabolic syndrome: the role of shear rate

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00811.2013 ◽

2014 ◽

Vol 306 (7) ◽

pp. H963-H971 ◽

Cited By ~ 12

Author(s):

Allan R. K. Sales ◽

Igor A. Fernandes ◽

Natália G. Rocha ◽

Lucas S. Costa ◽

Helena N. M. Rocha ◽

...

Keyword(s):

Metabolic Syndrome ◽

Shear Rate ◽

Endothelial Dysfunction ◽

Aerobic Exercise ◽

Brachial Artery ◽

Mental Stress ◽

Stress Test ◽

Flow Mediated Dilation ◽

Artery Flow

Mental stress induces transient endothelial dysfunction, which is an important finding for subjects at cardiometabolic risk. Thus, we tested whether aerobic exercise prevents this dysfunction among subjects with metabolic syndrome (MetS) and whether an increase in shear rate during exercise plays a role in this phenomenon. Subjects with MetS participated in two protocols. In protocol 1 ( n = 16), endothelial function was assessed using brachial artery flow-mediated dilation (FMD). Subjects then underwent a mental stress test followed by either 40 min of leg cycling or rest across two randomized sessions. FMD was assessed again at 30 and 60 min after exercise or rest, with a second mental stress test in between. Mental stress reduced FMD at 30 and 60 min after the rest session (baseline: 7.7 ± 0.4%, 30 min: 5.4 ± 0.5%, and 60 min: 3.9 ± 0.5%, P < 0.05 vs. baseline), whereas exercise prevented this reduction (baseline: 7.5 ± 0.4%, 30 min: 7.2 ± 0.7%, and 60 min: 8.7 ± 0.8%, P > 0.05 vs. baseline). Protocol 2 ( n = 5) was similar to protocol 1 except that the first period of mental stress was followed by either exercise in which the brachial artery shear rate was attenuated via forearm cuff inflation or exercise without a cuff. Noncuffed exercise prevented the reduction in FMD (baseline: 7.5 ± 0.7%, 30 min: 7.0 ± 0.7%, and 60 min: 8.7 ± 0.8%, P > 0.05 vs. baseline), whereas cuffed exercise failed to prevent this reduction (baseline: 7.5 ± 0.6%, 30 min: 5.4 ± 0.8%, and 60 min: 4.1 ± 0.9%, P < 0.05 vs. baseline). In conclusion, exercise prevented mental stress-induced endothelial dysfunction among subjects with MetS, and an increase in shear rate during exercise mediated this effect.

Download Full-text

P8.08 THE RELATIONSHIP BETWEEN BRACHIAL ARTERY FLOW-MEDIATED DILATION AND SHEAR RATE IN INDIVIDUALS WITH INCREASED CARDIOVASCULAR RISK

Artery Research ◽

10.1016/j.artres.2011.10.129 ◽

2011 ◽

Vol 5 (4) ◽

pp. 184

Author(s):

K. Aizawa ◽

S. Elyas ◽

F. D’Abate ◽

D. Majekolagbe ◽

A.C. Shore ◽

...

Keyword(s):

Cardiovascular Risk ◽

Shear Rate ◽

Brachial Artery ◽

Flow Mediated Dilation ◽

Artery Flow ◽

The Relationship

Download Full-text

Acute impact of retrograde shear rate on brachial and superficial femoral artery flow-mediated dilation in humans

Physiological Reports ◽

10.1002/phy2.193 ◽

2014 ◽

Vol 2 (1) ◽

pp. e00193 ◽

Cited By ~ 43

Author(s):

Tim H. A. Schreuder ◽

Daniel J. Green ◽

Maria T. E. Hopman ◽

Dick H. J. Thijssen

Keyword(s):

Shear Rate ◽

Femoral Artery ◽

Superficial Femoral Artery ◽

Flow Mediated Dilation ◽

Artery Flow ◽

Retrograde Shear

Download Full-text

Predictive value of brachial artery flow-mediated dilation on coronary artery abnormality in acute stage of Kawasaki disease

Scientific Reports ◽

10.1038/s41598-021-87704-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yizhou Wen ◽

Xianmin Wang ◽

Yonghong Guo ◽

Mei Jin ◽

Jimei Xi ◽

...

Keyword(s):

Coronary Artery ◽

Kawasaki Disease ◽

Brachial Artery ◽

Characteristic Curve ◽

Coronary Aneurysm ◽

Acute Stage ◽

Flow Mediated Dilation ◽

Strong Negative Correlation ◽

Coronary Artery Abnormality ◽

Artery Flow

AbstractCoronary artery abnormalities (CAAs) are a severe complication of Kawasaki disease (KD) that may lead to cardiovascular events. Given the evidence that brachial artery flow-mediated dilation (FMD) decreases in children after the onset of KD, we hypothesized that it could be an early marker of CAA development in the acute stage and investigated its relationship with variation in the coronary artery diameter. A total of 326 sex- and age-matched children were enrolled, including 120 with KD, 109 febrile children and 97 healthy controls. In this study, FMD was significantly decreased in the KD group compared with the febrile and healthy groups. FMD was lower in the CAA group than in the no coronary artery abnormality group. The comparison of FMD showed an obvious difference among the CAA subgroups. The FMD in the coronary aneurysm (CA) group showed a strong negative correlation with the pretreatment maximum coronary artery Z-score (preZmax). While preZmax was 2.5, the receiver operating characteristic curve indicated an optimal cutoff point of 3.44% for FMD. FMD ≤ 3.44% could be considered as a signal of coronary lesions in acute stage of KD.

Download Full-text