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

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

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

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Blair D Johnson ◽  
Kieren J Mather ◽  
Sean C Newcomer ◽  
Timothy D Mickleborough ◽  
Janet P Wallace
Keyword(s):  
Shear Rate ◽  
Brachial Artery ◽  
Flow Mediated Dilation ◽  
Artery Flow ◽  
Retrograde Shear

scholarly journals Brachial Artery Flow-Mediated Dilation and Asymmetrical Dimethylarginine in the Cardiovascular Risk in Young Finns Study

Circulation ◽  
2007 ◽  
Vol 116 (12) ◽  
pp. 1367-1373 ◽  
Author(s):  
Markus Juonala ◽  
Jorma S.A. Viikari ◽  
Georg Alfthan ◽  
Jukka Marniemi ◽  
Mika Kähönen ◽  
...  
Keyword(s):  
Cardiovascular Risk ◽  
Brachial Artery ◽  
Flow Mediated Dilation ◽  
Asymmetrical Dimethylarginine ◽  
Artery Flow ◽  
Young Finns Study

scholarly journals Contribution of nitric oxide to brachial artery vasodilation during progressive handgrip exercise in the elderly

2013 ◽  
Vol 305 (8) ◽  
pp. R893-R899 ◽  
Author(s):  
Joel D. Trinity ◽  
D. Walter Wray ◽  
Melissa A. H. Witman ◽  
Gwenael Layec ◽  
Zachary Barrett-O'Keefe ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Shear Rate ◽  
Brachial Artery ◽  
Vascular Function ◽  
The Elderly ◽  
Flow Mediated Dilation ◽  
Handgrip Exercise ◽  
Modest Contribution ◽  
Older Subjects ◽  
The Relationship

The reduction in nitric oxide (NO)-mediated vascular function with age has largely been determined by flow-mediated dilation (FMD). However, in light of recent uncertainty surrounding the NO dependency of FMD and the recognition that brachial artery (BA) vasodilation during handgrip exercise is predominantly NO-mediated in the young, we sought to determine the contribution of NO to BA vasodilation in the elderly using the handgrip paradigm. BA vasodilation during progressive dynamic (1 Hz) handgrip exercise performed at 3, 6, 9, and 12 kg was assessed with and without NO synthase (NOS) inhibition [intra-arterial NG-monomethyl-l-arginine (l-NMMA)] in seven healthy older subjects (69 ± 2 yr). Handgrip exercise in the control condition evoked significant BA vasodilation at 6 (4.7 ± 1.4%), 9 (6.5 ± 2.2%), and 12 kg (9.5 ± 2.7%). NOS inhibition attenuated BA vasodilation, as the first measurable increase in BA diameter did not occur until 9 kg (4.0 ± 1.8%), and the change in BA diameter at 12 kg was reduced by ∼30% (5.1 ± 2.2%), with unaltered shear rate (Control: 407 ± 57, l-NMMA: 427 ± 67 s−1). Although shifted downward, the slope of the relationship between BA diameter and shear rate during handgrip exercise was unchanged (Control: 0.0013 ± 0.0004, l-NMMA: 0.0011 ± 0.007, P = 0.6) as a consequence of NOS inhibition. Thus, progressive handgrip exercise in the elderly evokes a robust BA vasodilation, the magnitude of which was only minimally attenuated following NOS inhibition. This modest contribution of NO to BA vasodilation in the elderly supports the use of the handgrip exercise paradigm to assess NO-dependent vasodilation across the life span.

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

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

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

2019 ◽  
Vol 126 (6) ◽  
pp. 1687-1693 ◽  
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.

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

2014 ◽  
Vol 306 (7) ◽  
pp. H963-H971 ◽  
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.

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