Reactive hyperemic pre-ejection shear stress of brachial artery determines endothelial function in patients with untreated essential hypertension

2007 ◽  
Vol 122 (1) ◽  
pp. 68-71 ◽  
Author(s):  
Min-Yi Lee ◽  
Chih-Sheng Chu ◽  
Kun-Tai Lee ◽  
Chan-Ming Wu ◽  
Sheng-Hsiung Sheu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Essential Hypertension ◽  
Endothelial Function ◽  
Brachial Artery

Shear Stress Induced by Acute Heat Exposure Is Not Obligatory to Protect Against Endothelial Ischemia-reperfusion Injury in Humans

2021 ◽  
Author(s):  
Holden W. Hemingway ◽  
Rauchelle E. Richey ◽  
Amy M. Moore ◽  
Austin M. Shokraeifard ◽  
Gabriel C. Thomas ◽  
...  
Keyword(s):  
Shear Stress ◽  
Endothelial Function ◽  
Reperfusion Injury ◽  
Brachial Artery ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Whole Body ◽  
Flow Mediated Dilatation

Acute heat exposure protects against endothelial ischemia-reperfusion (I/R) injury in humans. However, the mechanism/s mediating this protective effect remain unclear. We tested the hypothesis that inhibiting the increase in shear stress induced by acute heat exposure would attenuate the protection of endothelial function following I/R injury. Nine (3 women) young healthy participants were studied under 3 experimental conditions: 1) thermoneutral control; 2) whole-body heat exposure to increase body core temperature by 1.2 °C; 3) heat exposure + brachial artery compression to inhibit the temperature-dependent increase in shear stress. Endothelial function was assessed via brachial artery flow-mediated dilatation before (pre-I/R) and after (post-I/R) 20 min of arm ischemia followed by 20 min of reperfusion. Brachial artery shear rate was increased during heat exposure (681 ± 359 s-1), but not for thermoneutral control (140 ± 63 s-1; P < 0.01 vs. heat exposure) nor heat + brachial artery compression (139 ± 60 s-1; P < 0.01 vs. heat exposure). Ischemia-reperfusion injury reduced flow-mediated dilatation following thermoneutral control (pre-I/R, 5.5 ± 2.9 % vs. post-I/R, 3.8 ± 2.9 %; P = 0.06), but was protected following heat exposure (pre-I/R, 5.8 ± 2.9 % vs. post-I/R, 6.1 ± 2.9 %; P = 0.5) and heat + arterial compression (pre-I/R, 4.4 ± 2.8 % vs. post-I/R, 5.8 ± 2.8 %; P = 0.1). Contrary to our hypothesis, our findings demonstrate that shear stress induced by acute heat exposure is not obligatory to protect against endothelial I/R injury in humans.

scholarly journals Examining the acute effects of retrograde versus low mean shear rate on flow-mediated dilation

2019 ◽  
Vol 126 (5) ◽  
pp. 1335-1342 ◽  
Author(s):  
Joshua C. Tremblay ◽  
Arman S. Grewal ◽  
Kyra E. Pyke
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Endothelial Function ◽  
Brachial Artery ◽  
Duplex Ultrasound ◽  
Flow Mediated Dilation ◽  
Relative Contribution ◽  
Stress Components ◽  
Retrograde Shear

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.

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.

Endothelial dysfunction in workers in underground mining of chrome ores

2019 ◽  
pp. 914-919
Author(s):  
N. V. Zaitseva ◽  
A. E. Nosov ◽  
Ju. A. Ivashova ◽  
A. S. Baidina ◽  
V. G. Kostarev
Keyword(s):  
Shear Stress ◽  
Endothelial Dysfunction ◽  
Endothelial Function ◽  
Working Conditions ◽  
Brachial Artery ◽  
Comparison Group ◽  
Underground Mining ◽  
Relative Increase ◽  
Observation Group ◽  
Brachial Artery Diameter

Introduction. Currently, endothelial dysfunction is considered as one of the initial stages of the pathogenesis of cardiovascular diseases. By isolating a number of biologically active compounds, the endothelium helps to maintain vascular tone and physiological rheology of the blood. Modern production of chrome ore is characterized by a variety of harmful occupational factors (chromium, dust, noise, vibration, severity and intensity of work, cooling microclimate), which can disrupt the normal functioning of the vascular endothelium and lead to the development of cardiovascular diseases.The aim of the study was to study the features of endothelial function in workers engaged in underground mining of chrome ore in harmful working conditions.Materials and methods. The study included 98 miners of the enterprise for the extraction of chrome ore. The comparison group (working in conditions outside the influence of the studied production factors) consisted of 75 employees-managers and specialists of administrative and managerial personnel of the enterprise, comparable in age and experience with the observation group. To assess the vasomotor function of the endothelium, a flow-dependent (endothelium-dependent) vasodilation test was performed using the D. S. Celermajer technique. Post-occlusive increase in brachial artery diameter, brachial artery sensitivity coefficient to endothelial shift change were evaluated.Results. The endothelial function of mine workers did not differ significantly from the comparison group with work experience up to 10 years (the values of the relative increase in the diameter of the brachial artery 12.2% in the observation group and in the comparison group 12.6%, p=0.74). With experience of more than 10 years, the value of the relative increase in the diameter of the brachial artery in the observation group with experience of more than 10 years corresponded to the signs of endothelial dysfunction and amounted to 8.6%, while in the comparison group this figure was 12.4%, which corresponded to normal endothelial function (p=0.019). Endothelial function progressively deteriorated with increasing seniority in mine workers. Conclusions. For workers engaged in underground mining of chrome ore for more than 10 years, a reduced vasodilation reaction to reperfusion after an occlusion test and a low coefficient of sensitivity of the endothelium to shear stress are characteristic. There was no statistically significant decrease in increase in brachial artery diameter and the coefficient of sensitivity of endothelium to shear stress relative to the comparison group was selected only from persons with experience more than 10 years. The comparative analysis of the results of the evaluation of the functional activity of the endothelium in workers of the compared groups indicates that the change in the functional state of the endothelium in miners is associated not only with age, but also with working conditions. The revealed changes predispose to the development of cardiovascular pathology associated with atherosclerosis in workers of underground chrome ore mining.

scholarly journals Effect of empagliflozin on brachial artery shear stress and endothelial function in subjects with type 2 diabetes: Results from an exploratory study

2019 ◽  
Vol 17 (1) ◽  
pp. 147916411988354 ◽  
Author(s):  
Concetta Irace ◽  
Antonio Cutruzzolà ◽  
Martina Parise ◽  
Raffaella Fiorentino ◽  
Marco Frazzetto ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Shear Stress ◽  
Endothelial Function ◽  
Brachial Artery ◽  
Therapy Group ◽  
Glycated Haemoglobin ◽  
Flow Mediated Dilation ◽  
Endothelial Surface ◽  
Significant Difference

Empagliflozin reduces the risk of cardiovascular mortality in subjects with type 2 diabetes. We demonstrated that empagliflozin increases blood viscosity and carotid shear stress and decreases carotid wall thickness. Shear stress is the force acting on the endothelial surface and modulates arterial function. The current study evaluates the influence of empagliflozin on brachial artery shear stress and endothelial function compared to incretin-based therapy. The study is a nonrandomized, open, prospective cohort study including 35 subjects with type 2 diabetes administered empagliflozin or incretin-based therapy. Shear stress was calculated with a validated formula, and endothelial function was evaluated using the flow-mediated dilation technique. Both treatments resulted in comparable reductions in blood glucose and glycated haemoglobin. Brachial artery shear stress significantly increased exclusively in the empagliflozin group (61 ± 20 vs 68 ± 25 dynes/cm2, p = 0.04), whereas no significant difference was detected in the incretin-based therapy group (60 ± 20 vs 55 ± 12 dynes/cm2, p = not significant). Flow-mediated dilation significantly increased in the empagliflozin group (4.8 ± 4.5% vs 8.5 ± 5.6%, p = 0.03). Again, no change was detected in the incretin-based therapy group (5.1 ± 4.5% vs 4.7 ± 4.7%, p = not significant). The present findings demonstrate the beneficial effect of empagliflozin on shear stress and endothelial function in subjects with type 2 diabetes independent of the hypoglycaemic effect.

Effect of acute blood pressure reduction on endothelial function in the brachial artery of patients with essential hypertension

2001 ◽  
Vol 19 (Supplement) ◽  
pp. 547-551 ◽  
Author(s):  
Lorenzo Ghiadoni ◽  
Yale Huang ◽  
Armando Magagna ◽  
Simona Buralli ◽  
Stefano Taddei ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Essential Hypertension ◽  
Endothelial Function ◽  
Brachial Artery ◽  
Blood Pressure Reduction ◽  
Pressure Reduction

Aging and Endothelial Function in Normotensive Subjects and Patients With Essential Hypertension

Circulation ◽  
1995 ◽  
Vol 91 (7) ◽  
pp. 1981-1987 ◽  
Author(s):  
Stefano Taddei ◽  
Agostino Virdis ◽  
Paola Mattei ◽  
Lorenzo Ghiadoni ◽  
Alessandra Gennari ◽  
...  
Keyword(s):  
Essential Hypertension ◽  
Endothelial Function ◽  
Normotensive Subjects

scholarly journals Comparison of biomarkers of endothelial dysfunction and microvascular endothelial function in patients with primary aldosteronism and essential hypertension

2021 ◽  
Vol 22 (1) ◽  
pp. 147032032199949
Author(s):  
Miaomiao Sang ◽  
Yu Fu ◽  
Chenmin Wei ◽  
Jing Yang ◽  
Xueting Qiu ◽  
...  
Keyword(s):  
Essential Hypertension ◽  
Endothelial Dysfunction ◽  
Endothelial Function ◽  
Primary Aldosteronism ◽  
Cardiovascular Events ◽  
Statistical Significance ◽  
Enzyme Linked Immunosorbent Assay ◽  
Microvascular Endothelial ◽  
Pai 1 ◽  
Microvascular Endothelial Function

Introduction: Studies have shown that primary aldosteronism (PA) has a higher risk of cardiovascular events than essential hypertension (EH). Endothelial dysfunction is an independent predictor of cardiovascular events. Whether PA and EH differ in the endothelial dysfunction is uncertain. Our study was designed to investigate the levels of biomarkers of endothelial dysfunction (Asymmetric dimethylarginine, ADMA; E-selectin, and Plasminogen activator inhibitor-1, PAI-1) and assess the microvascular endothelial function in patients with PA and EH, respectively. Methods: The biomarkers of endothelial dysfunction were measured by enzyme-linked immunosorbent assay (ELISA). Microvascular endothelial function was evaluated by Pulse amplitude tonometry (PAT). Results: Thirty-one subjects with EH and 36 subjects with PA including 22 with aldosterone-producing adenoma (APA) and 14 with idiopathic hyperaldosteronism (IHA) were enrolled in our study. The ADMA levels among the three groups were different (APA 47.83 (27.50, 87.74) ng/ml vs EH 25.08 (22.44, 39.79) ng/ml vs IHA 26.00 (22.23, 33.75) ng/ml; p = 0.04), however, when the APA group was compared with EH and IHA group, there was no statistical significance (47.83 (27.50, 87.74) ng/ml vs 25.08 (22.44, 39.79) ng/ml for EH, p = 0.11; 47.83 (27.50, 87.74) ng/ml vs IHA 26.00 (33.75) ng/ml, p = 0.07). The results of ADMA levels are presented as Median (p25, p75). Whereas, levels of PAI-1 and E-selectin, microvascular endothelial function were not significantly different between PA and EH subjects. Conclusions: Our study shows no significant differences between PA and EH in terms of biomarkers of endothelial dysfunction and microvascular endothelial function. The microvascular endothelial function of PA and EH patients is comparable.

Flow-mediated dilatation following wrist and upper arm occlusion in humans: the contribution of nitric oxide

2001 ◽  
Vol 101 (6) ◽  
pp. 629-635 ◽  
Author(s):  
Sagar N. DOSHI ◽  
Katerina K. NAKA ◽  
Nicola PAYNE ◽  
Christopher J.H. JONES ◽  
Moira ASHTON ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Function ◽  
Brachial Artery ◽  
Peak Flow ◽  
Ultrasound Probe ◽  
Upper Arm ◽  
Flow Mediated Dilatation ◽  
Synthase Inhibitor ◽  
Increased Blood Flow ◽  
Similar Peak

Flow-mediated dilatation (FMD) of the brachial artery assessed by high-resolution ultrasound is widely used to measure endothelial function. However, the technique is not standardized, with different groups using occlusion of either the wrist or the upper arm to induce increased blood flow. The validity of the test as a marker of endothelial function rests on the assumption that the dilatation observed is endothelium-dependent and mediated by nitric oxide (NO). We sought to compare the NO component of brachial artery dilatation observed following wrist or upper arm occlusion. Dilatation was assessed before and during intra-arterial infusion of the NO synthase inhibitor NG-monomethyl-l-arginine (l-NMMA) following occlusion of (i) the wrist (distal to ultrasound probe) and (ii) the upper arm (proximal to ultrasound probe) for 5min in ten healthy males. Dilatation was significantly greater after upper arm occlusion (upper arm, 11.62±3.17%; wrist, 7.25±2.49%; P = 0.003). During l-NMMA infusion, dilatation after wrist occlusion was abolished (from 7.25±2.49% to 0.16±2.24%; P < 0.001), whereas dilatation after upper arm occlusion was only partially attenuated (from 11.62±3.17% to 7.51±2.34%; P = 0.006). The peak flow stimulus was similar after wrist and upper arm occlusion. We conclude that dilatation following upper arm occlusion is greater than that observed after wrist occlusion, despite a similar peak flow stimulus. l-NMMA infusion revealed that FMD following wrist occlusion is mediated exclusively by NO, while dilatation following upper arm occlusion comprises a substantial component not mediated by NO, most probably related to tissue ischaemia around the brachial artery. FMD following wrist occlusion may be a more valid marker of endothelial function than dilatation following upper arm occlusion.

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