Endothelium-independent Dilation Research Articles

Static Muscle Stretching Enhances Vascular Responsiveness of the Tibial Nutrient Artery

The magnitude of bone formation and remodeling is linked to both the magnitude of strain placed on the bone and the perfusion of bone. We have previously shown that daily static stretching of the ankle flexor muscles in aged rats results in increased blood flow to the stretched muscles and to the proximal tibial metaphasis during walking exercise. The purpose of this study was to determine the effects of daily static muscle stretching on vasoreactivity of the nutrient artery that perfuses the proximal tibial metaphasis. Static stretching of ankle flexor muscles was performed in aged male Fischer 344 rats (20 months) by placement of a dorsiflexion splint on the left ankle for 30 min/day, 5d/wk for 4wks. The right hindlimb served as a contralateral control (unstretched) limb. After the 4 wk stretching intervention, the tibial nutrient artery was isolated from both the stretched and unstretched limb. Vasoconstrictor responses to the adrenergic agonist, phenylephrine (10‐9‐10‐4M) and vasodilatory responses to acetylcholine (10‐9‐10‐4M) and Dea‐NONO‐ate (10‐9‐10‐4M) were evaluated. Vasoconstrictor responses to phenylephrine were significantly increased in the tibial nutrient artery from the stretched limb as compared to those from the unstretched limb (maximal constriction, stretched limb = 54±4%, maximal constriction, unstretched limb = 42±6%; P<0.05 stretched vs. unstretched). Endothelium‐dependent vasodilation to acetylcholine was also significantly increased in the tibial nutrient artery from the stretched limb (maximal dilation = 62±5%) as compared to the unstretched limb (maximal dilation = 41±5%); P<0.01, stretched vs. unstretched). Endothelium‐independent dilation to the NO donor, Dea‐NONO‐ate was not different in the tibial nutrient arteries from the stretched and unstretched limbs. These data indicate that static muscle stretching alters the reactivity of both the smooth muscle and the endothelium of the tibial nutrient artery, leading to enhanced vasoconstrictor and vasodilatory responsiveness of the artery. This enhancement of vascular function in the nutrient artery may contribute to increased perfusion of the tibia during walking exercise following 4 weeks of daily static stretching.Support or Funding InformationSupported By: NIH R15AG055029

Effects of diabetic foot infection on vascular and immune function in the lower limbs

The study investigated the effects of diabetic foot infection on vascular and immune function in the lower limbs. Seventy-two patients with diabetic foot infection were included in the infected group, while 64 diabetic patients without infection were selected as the control group. Hemodynamic parameters and vascular endothelial function of the dorsalis pedis artery were assessed by color Doppler ultrasonography. Enzyme-linked immunosorbent assay was used to determine the serum levels of interleukin 6 (IL-6), IL-17, tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), and high mobility group box 1 protein (HMGB1). Western blotting was used to quantify expression levels of toll-like receptor 4 (TLR4) and nuclear transcription factor kappa B (NFκB) in human peripheral blood mononuclear cells (PBMC). Compared with the control group, the intima-media thickness and peak systolic velocity of the infected group were increased (both p < 0.05), while the inner vascular diameter, blood flow volume, endothelium-dependent dilation, and endothelium-independent dilation were decreased (all p < 0.05). Compared with the control group, the serum levels of IL-6, IL-17, TNF-α, CRP, and HMGB1, and the expression levels of TLR4 and NFκB in PBMC were significantly increased in the infected group (all p < 0.001). Thus, diabetic foot infection is associated with vascular and immune dysfunction in the lower limbs, possibly in relation to the activation of the HMGB1/TLR4/NFκB signaling pathway.

Daily Passive Muscle Stretching Improves Flow-Mediated Dilation of Popliteal Artery and 6-minute Walk Test in Elderly Patients with Stable Symptomatic Peripheral Artery Disease.

Patients with peripheral arterial disease (PAD) often have walking impairment due to insufficient oxygen supply to skeletal muscle. In aged rats, we have shown that daily stretching of calf muscles improves endothelium-dependent dilation of arterioles from the soleus muscle and increases capillarity and muscle blood flow during exercise. Therefore, we hypothesized that daily muscle stretching of calf muscles would improve endothelium-dependent vasodilation of the popliteal artery and walking function in PAD patients. We performed a randomized, non-blinded, crossover study whereby 13 patients with stable symptomatic PAD were randomized to undergo either 4 weeks of passive calf muscle stretching (ankle dorsiflexion applied 30 min/d, 5 days/wk) followed by 4 weeks of no muscle stretching and vice versa. Endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent nitroglycerin-induced dilation of the popliteal artery and 6 minute walk test (6MWT) were evaluated at baseline and after each 4 week interval. After 4 weeks of muscle stretching, FMD and 6MWT improved significantly in the muscle stretching group vs. the control (FMD: 5.1 ± 0.5% vs. 3.7 ± 0.3%, P = 0.005; 6MWT continuous walking distance: 304 ± 43 m vs. 182 ± 34 m; P = 0.0006). No difference in nitroglycerin-induced dilation was found between groups (10.9 ± 1.2 vs. 9.9 ± 0.4%, P = 0.48). Post-stretching, 6MWT total walking distance was positively correlated with normalized FMD (R = 0.645, P = 0.02). Passive calf muscle stretching enhanced vascular endothelial function and improved walking function in elderly patients with stable symptomatic PAD. These findings merit further investigation in a prospective randomized trial.

Transfer of Young Gut Microbiota Ameliorates Age‐ and Western‐Style Diet‐Related Vascular Endothelial Dysfunction in Mice

Aging is associated with vascular endothelial dysfunction largely driven by reduced nitric oxide (NO) bioavailability, which increases the risk of cardiovascular diseases (CVD). Consumption of a Western‐style diet (WD; high fat, high sugar, low fiber) exacerbates this dysfunction and CVD risk. Adverse changes to the gut microbiome (gut dysbiosis) are observed with aging and/or WD and are linked to atherosclerosis and clinical CVD. We have shown that suppression of the gut microbiome with broad‐spectrum antibiotics in old mice reverses endothelial dysfunction, as indicated by improved endothelium‐dependent dilation (EDD). As it is impractical to use prolonged antibiotic treatment to prevent CVD, a novel approach would be to improve vascular function via microbiome transfer from healthy donors to recipients with endothelial dysfunction.PURPOSETo determine whether fecal microbiota transfer (FMT) from young, healthy mice reverses age‐ and/or WD‐induced endothelial dysfunction.METHODSOlder male C57Bl/6 mice were fed either standard chow (OC) or WD chow (started at 22 mo; OWD). Beginning at age 25 mo, following 5–7 days of antibiotic administration to suppress endogenous microbiota, mice were administered FMTs (feces collected pre‐treatment) via oral gavage from either young, healthy (YC; age 3–6 mo) mice (OC+YC, N=6; OWD+YC, N=6) or their own cohort (“self” recipients: OC+OC, N=7; OWD+OWD, N=5) weekly for 8 weeks. Following sacrifice at 27 mo, EDD was measured ex vivo in common carotid arteries as dilation to increasing doses of acetylcholine (10−9 to 10−4M). NO‐mediated dilation was assessed as the difference in EDD in the presence vs. absence of the endothelial NO synthase inhibitor L‐NAME. Endothelium‐independent dilation (EID) was assessed as dilation to the NO donor sodium nitroprusside (10−10 to 10−4M). These outcomes were also assessed in the group of YC donors (N=11), as a healthy reference. Data are mean±S.E.% of maximal dilation; p‐values determined by unpaired t‐test.RESULTSAge‐ and WD‐induced decreases in peak EDD (YC: 93.0±1.6%; OC+OC: 63.8±3.0%, p&lt;0.001 vs. YC; OWD+OWD: 53.6±9.1%, p&lt;0.001 vs. YC) were or tended to be ameliorated by FMT from YC mice (OC+YC: 77.4±2.5%, p&lt;0.01 vs. OC+OC; OWD+YC: 76.7±8.3%, p=0.09 vs. OWD+OWD). These effects were likely mediated by improvements in NO bioavailability, as age‐ and WD‐induced reductions in NO‐mediated dilation (YC: 43.4±7.0%; OC+OC: 29.4±6.4%, p&lt;0.001 vs. YC; OWD+OWD: 29.9±8.8%, p=0.21 vs. YC) were or tended to be improved by FMT from YC mice (OC+YC: 51.2±5.5%, p=0.04 vs. OC+OC; OWD+YC: 41.5±7.5%, p=0.34 vs. OWD+OWD). There were no differences in EID across groups (YC: 94.9±1.4%; OWD+OWD: 92.6±2.6%; OC+OC: 93.5±2.5%; OWD+YC: 98.7±0.6%; OC+YC: 93.6±3.9%, all p&gt;0.05 vs. YC), indicating that the group differences in EDD were endothelium‐dependent.CONCLUSIONSThese preliminary data offer initial proof‐of‐concept evidence that the gut microbiome modulates endothelial function with aging and WD, and that alteration of the gut microbiome via FMT from healthy donors may confer improved endothelial function and possibly lower CVD risk.Support or Funding InformationSupported by: R01 HL134887, F32 HL140875This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

In Utero Exposure to Electronic Cigarettes Causes Cerebrovascular Impairment with Aging

Electronic cigarettes (Ecigs) are being promoted as safer than traditional tobacco cigarettes, leading to increased use even during pregnancy. However, the risks associated with Ecig usage during pregnancy on offspring has not been examined.Rat dams were either exposed to nicotine‐free Ecig vapor (Ecig+0) or ambient air. Rat pups were sacrificed at either one month (Air n=6, Ecig+0 n=5) or three months (Air n=4, Ecig+0 n=3). Maternal Ecig exposure (Joyetech eGrip OLED using 5‐sec puff @ 17.5 W) consisted of 30 puffs over 1‐hour each day, 5 days/week, resulting in an average daily TPM of 120mg/m3. Maternal exposure began on gestational day 2 and continued until pups were weaned. Pups themselves were never directly exposed to Ecig vapors. To examine cerebrovascular function, the middle cerebral artery (MCA) was isolated positioned in a pressurized myobath and exposed to increasing concentrations of acetylcholine (Ach; 10−9M to 10−4M), serotonin (5‐HT; 10−9M to 10−4M) and sodium nitroprusside (SNP; 10−9M to 10−4M).Significant impairment in MCA dilation to the highest dose of Ach was observed in Ecig+0 compared to air exposed pups at one month of age (13±2% vs. 30±1%, ANOVA p&lt;0.05, respectively) as well as at three months of age (8±1% vs 23±2%, ANOVA p&lt;0.05, respectively). The magnitude of decline in vascular reactivity for Ecig+0 exposed pups at one month and three months was different, although not statistically significant (ANOVA p&lt;0.08). MCA constriction to 5‐HT was similar across all groups and only slight nonsignificant differences were noted in endothelial‐independent dilation in response to SNP.These data suggest offspring born to mothers who vape during pregnancy have impaired cerebrovascular function, with this impairment worsening with age, suggesting there are risks to the offspring associated with maternal Ecig use.Support or Funding InformationWVU Cancer Institute Philip R Dino Innovative Research Grant (IMO); APS STRIDE Fellowship (JO); NIHGMS 5U54GM104942‐03 (PDC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Dietary Glycocalyx Precursor Supplementation Ameliorates Age‐Related Vascular Dysfunction

Large elastic artery stiffening and endothelial dysfunction, and associated reductions in nitric oxide (NO) bioavailability, are central features of vascular aging. We have recently demonstrated that the glycocalyx, a gel‐like structure that is bound to the luminal surface of the vascular endothelium, is dysfunctional in the aged vasculature. The glycocalyx has several functions that are critical for the maintenance of a healthy vasculature. We sought to determine if chronic dietary supplementation of glycocalyx precursors (glucosamine sulfate, fucoidan, superoxide dismutase, and high molecular weight hyaluronan) could restore glycocalyx function, while concomitantly ameliorating age‐related vascular dysfunction. Young (Y: 7 mo) and old (O: 30 mo) male B6D2F1 mice consumed a control (C) or glycocalyx precursor (GP: 37 mg/kg encapsulated chow provided courtesy of MicroVascular Health Solutions, LLC [U.S. Patent Serial No. 9,943,572]) diet ad libitum for 10 weeks. Glycocalyx barrier function (perfused boundary region [PBR]) was evaluated in the mesenteric microcirculation using an intravital microscope equipped with an automated capture and analysis system. PBR was ~13% higher in OC compared to YC, suggestive of an age‐related impairment in glycocalyx barrier function, and this was normalized in OGP mice (Both P&lt;0.05; Figure 1). At baseline, aortic pulse wave velocity (PWV), a measure of large artery stiffness, was higher in OC and OGP compared with YC mice (Both P&lt;0.05; Figure 2). However, after the dietary intervention, PWV decreased by ~13% in OGP (P&lt;0.05), whereas, PWV was unchanged in OC and YC mice after the 10 week period (P&gt;0.05). We assessed endothelial function by endothelium‐dependent dilation (EDD, maximal response to acetylcholine [ACh]) in the carotid artery. Carotid artery EDD was higher in YC and OGP compared to OC mice (92.5±2.4 and 90.7±2.3 vs. 69.0±4.9%, respectively, P&lt;0.05). EDD of OGP was similar to YC mice (P&gt;0.05). After incubation with the nitric oxide (NO) synthase inhibitor, L‐NAME, the dilatory response did not differ between groups (P&gt;0.05). NO bioavailability (max ACh dilation ‐ max ACh+L‐NAME dilation) was ~10–14 fold higher in YC and OGP compared to OC mice (Both P&lt;0.05; Figure 3). Endothelium‐independent dilation (vasodilation to sodium nitroprusside) was not different between groups (P&gt;0.05). In young mice, GP diet did not affect any of the aforementioned measurements (P&gt;0.05). In conclusion, 10 weeks of dietary GP supplementation in old mice restores glycocalyx barrier function that is accompanied by reduced aortic stiffness and augmented EDD and NO bioavailability, suggesting that the glycocalyx may be an effective therapeutic target for vascular dysfunction in older adults.Support or Funding InformationThis study was funded in part by grants from the National Institute of Health (R01 AG040297, R01 AG048366, K02 AG045339, K99 AT010017) and US Department of Veterans Affairs (1I01BX002151).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Altered bioavailability of epoxyeicosatrienoic acids is associated with conduit artery endothelial dysfunction in type 2 diabetic patients

BackgroundThis pathophysiological study addressed the hypothesis that soluble epoxide hydrolase (sEH), which metabolizes the vasodilator and anti-inflammatory epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs), contributes to conduit artery endothelial dysfunction in type 2 diabetes.Methods and resultsRadial artery endothelium-dependent flow-mediated dilatation in response to hand skin heating was reduced in essential hypertensive patients (n = 9) and type 2 diabetic subjects with (n = 19) or without hypertension (n = 10) compared to healthy subjects (n = 36), taking into consideration cardiovascular risk factors, flow stimulus and endothelium-independent dilatation to glyceryl trinitrate. Diabetic patients but not non-diabetic hypertensive subjects displayed elevated whole blood reactive oxygen species levels and loss of NO release during heating, assessed by measuring local plasma nitrite variation. Moreover, plasma levels of EET regioisomers increased during heating in healthy subjects, did not change in hypertensive patients and decreased in diabetic patients. Correlation analysis showed in the overall population that the less NO and EETs bioavailability increases during heating, the more flow-mediated dilatation is reduced. The expression and activity of sEH, measured in isolated peripheral blood mononuclear cells, was elevated in diabetic but not hypertensive patients, leading to increased EETs conversion to DHETs. Finally, hyperglycemic and hyperinsulinemic euglycemic clamps induced a decrease in flow-mediated dilatation in healthy subjects and this was associated with an altered EETs release during heating.ConclusionsThese results demonstrate that an increased EETs degradation by sEH and altered NO bioavailability are associated with conduit artery endothelial dysfunction in type 2 diabetic patients independently from their hypertensive status. The hyperinsulinemic and hyperglycemic state in these patients may contribute to these alterations.Trial registration NCT02311075. Registered December 8, 2014.

Oxidative Stress Contributes to Microvascular Endothelial Dysfunction in Men and Women With Major Depressive Disorder.

In rodent models of depression, oxidative stress-induced reductions in NO bioavailability contribute to impaired endothelium-dependent dilation. Endothelial dysfunction is evident in major depressive disorder (MDD); however, the molecular mediators remain undefined. We sought to translate preclinical findings to humans by testing the role of oxidative stress in mediating microvascular endothelial dysfunction, including potential modulatory influences of sex, in MDD. Twenty-four treatment-naive, otherwise healthy, young adults with MDD (14 women; 18-23 years) and 20 healthy adults (10 women; 19-30 years) participated. Red blood cell flux (laser Doppler flowmetry) was measured during graded intradermal microdialysis perfusion of the endothelium-dependent agonist acetylcholine, alone and in combination with an NO synthase inhibitor (L-NAME), a superoxide scavenger (Tempol), and an NADPH oxidase inhibitor (apocynin), as well as during perfusion of the endothelium-independent agonist sodium nitroprusside. Tissue oxidative stress markers (eg, nitrotyrosine abundance, superoxide production) were also quantified. Endothelium-dependent dilation was blunted in MDD and mediated by reductions in NO-dependent dilation. Endothelium-independent dilation was likewise attenuated in MDD. In MDD, there were no sex differences in either NO-mediated endothelium-dependent dilation or endothelium-independent dilation. Acute scavenging of superoxide or inhibition of NADPH oxidase improved NO-dependent dilation in MDD. Expression and activity of oxidative stress markers were increased in MDD. In a subset of adults with MDD treated with a selective serotonin reuptake inhibitor for their depressive symptoms and in remission (n=8; 7 women; 19-37 years), NO-mediated endothelium-dependent dilation was preserved, but endothelium-independent dilation was impaired, compared with healthy adults. Oxidative stress-induced reductions in NO-dependent dilation, as well as alterations in vascular smooth muscle function, directly contribute to microvascular dysfunction in MDD. Strategies targeting vascular oxidative stress may be viable therapeutic options for improving NO-mediated endothelial function and reducing cardiovascular risk in MDD.

Deep Vascular Phenotyping in Patients With Renal Multifocal Fibromuscular Dysplasia.

Arterial fibromuscular dysplasia is a nonatherosclerotic, noninflammatory vascular disease, whose pathophysiology is still unknown. We performed deep image-based vascular phenotyping of nonaffected arteries to look for systemic vascular alterations in fibromuscular dysplasia. This single center cross-sectional study included 50 patients with multifocal renal fibromuscular dysplasia, 50 hypertensive patients, and 50 healthy controls, matched for age, sex, and ethnicity; hypertensive patients were matched also for blood pressure. Brachial artery endothelium-dependent and endothelium-independent dilation were studied by echotracking. Aortic stiffness was assessed by carotid-to-femoral pulse wave velocity. We quantified the presence of supernumerary acoustic interfaces within the common carotid wall by the triple signal (TS) score. We plotted the Young incremental elastic modulus/stress curves for common carotid artery, derived from echotracking and tonometry. Patients with fibromuscular dysplasia had impaired endothelium-independent dilation (adjusted P=0.002), smaller brachial artery diameter but comparable endothelium-dependent dilation and aortic stiffness. The prevalence of TS score >6 was 56%, 40%, 24% in patients with fibromuscular dysplasia, hypertensives, and controls, respectively ( P=0.005). Fibromuscular dysplasia remained significantly associated with TS in the multiple regression model ( P=0.022). Impaired endothelium-dependent dilation was present only in patients with fibromuscular dysplasia, TS score >6 ( P=0.047). Incremental elastic modulus was higher for a given wall stress (80 kPa) in the presence of a TS score >6, especially in fibromuscular dysplasia. In conclusion, nonclinically affected large- and medium-sized arteries in patients with multifocal renal fibromuscular dysplasia exhibit a cluster of diffuse alterations in smooth muscle cell function, arterial geometry, wall characteristics, and mechanical properties. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT01935752.

Amplification of endothelium-dependent vasodilatation in contracting human skeletal muscle: role of KIR channels.

In humans, the vasodilatory response to skeletal muscle contraction is mediated in part by activation of inwardly rectifying potassium (KIR ) channels. Evidence from animal models suggest that KIR channels serve as electrical amplifiers of endothelium-dependent hyperpolarization (EDH). We found that skeletal muscle contraction amplifies vasodilatation to the endothelium-dependent agonist ACh, whereas there was no change in the vasodilatory response to sodium nitroprusside, an endothelium-independent nitric oxide donor. Blockade of KIR channels reduced the exercise-induced amplification of ACh-mediated vasodilatation. Conversely, pharmacological activation of KIR channels in quiescent muscle via intra-arterial infusion of KCl independently amplified the vasodilatory response to ACh. This study is the first in humans to demonstrate that specific endothelium-dependent vasodilatory signalling is amplified in the vasculature of contracting skeletal muscle and that KIR channels may serve as amplifiers of EDH-like vasodilatory signalling in humans. The local vasodilatory response to muscle contraction is due in part to the activation of inwardly rectifying potassium (KIR ) channels. Evidence from animal models suggest that KIR channels function as 'amplifiers' of endothelium-dependent vasodilators. We tested the hypothesis that contracting muscle selectively amplifies endothelium-dependent vasodilatation via activation of KIR channels. We measured forearm blood flow (Doppler ultrasound) and calculated changes in vascular conductance (FVC) to local intra-arterial infusion of ACh (endothelium-dependent dilator) during resting conditions, handgrip exercise (5% maximum voluntary contraction) or sodium nitroprusside (SNP; endothelium-independent dilator) which served as a high-flow control condition (n= 7, young healthy men and women). Trials were performed before and after blockade of KIR channels via infusion of barium chloride. Exercise augmented peak ACh-mediated vasodilatation (ΔFVC saline: 117± 14; exercise: 236± 21mlmin-1 (100mmHg)-1 ; P< 0.05), whereas SNP did not impact ACh-mediated vasodilatation. Blockade of KIR channels attenuated the exercise-induced augmentation of ACh. In eight additional subjects, SNP was administered as the experimental dilator. In contrast to ACh, exercise did not alter SNP-mediated vasodilatation (ΔFVC saline: 158± 35; exercise: 121± 22mlmin-1 (100mmHg)-1 ; n.s.). Finally, in a subset of six subjects, direct pharmacological activation of KIR channels in quiescent muscle via infusion of KCl amplified peak ACh-mediated vasodilatation (ΔFVC saline: 97± 15, KCl: 142± 16mlmin-1 (100mmHg)-1 ; respectively; P< 0.05). These findings indicate that skeletal muscle contractions selectively amplify endothelium-dependent vasodilatory signalling via activation of KIR channels, and this may be an important mechanism contributing to the normal vasodilatory response to exercise in humans.

Group II innate lymphoid cells and microvascular dysfunction from pulmonary titanium dioxide nanoparticle exposure

BackgroundThe cardiovascular effects of pulmonary exposure to engineered nanomaterials (ENM) are poorly understood, and the reproductive consequences are even less understood. Inflammation remains the most frequently explored mechanism of ENM toxicity. However, the key mediators and steps between lung exposure and uterine health remain to be fully defined. The purpose of this study was to determine the uterine inflammatory and vascular effects of pulmonary exposure to titanium dioxide nanoparticles (nano-TiO2). We hypothesized that pulmonary nano-TiO2 exposure initiates a Th2 inflammatory response mediated by Group II innate lymphoid cells (ILC2), which may be associated with an impairment in uterine microvascular reactivity.MethodsFemale, virgin, Sprague-Dawley rats (8–12 weeks) were exposed to 100 μg of nano-TiO2 via intratracheal instillation 24 h prior to microvascular assessments. Serial blood samples were obtained at 0, 1, 2 and 4 h post-exposure for multiplex cytokine analysis. ILC2 numbers in the lungs were determined. ILC2s were isolated and phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB) levels were measured. Pressure myography was used to assess vascular reactivity of isolated radial arterioles.ResultsPulmonary nano-TiO2 exposure was associated with an increase in IL-1ß, 4, 5 and 13 and TNF- α 4 h post-exposure, indicative of an innate Th2 inflammatory response. ILC2 numbers were significantly increased in lungs from exposed animals (1.66 ± 0.19%) compared to controls (0.19 ± 0.22%). Phosphorylation of the transactivation domain (Ser-468) of NF-κB in isolated ILC2 and IL-33 in lung epithelial cells were significantly increased (126.8 ± 4.3% and 137 ± 11% of controls respectively) by nano-TiO2 exposure. Lastly, radial endothelium-dependent arteriolar reactivity was significantly impaired (27 ± 12%), while endothelium-independent dilation (7 ± 14%) and α-adrenergic sensitivity (8 ± 2%) were not altered compared to control levels. Treatment with an anti- IL-33 antibody (1 mg/kg) 30 min prior to nano-TiO2 exposure resulted in a significant improvement in endothelium-dependent dilation and a decreased level of IL-33 in both plasma and bronchoalveolar lavage fluid.ConclusionsThese results provide evidence that the uterine microvascular dysfunction that follows pulmonary ENM exposure may be initiated via activation of lung-resident ILC2 and subsequent systemic Th2-dependent inflammation.

ENDOTHELIAL FUNCTION IS ASSOCIATED WITH TRIPLE SIGNAL IN FIBROMUSCULAR DYSPLASIA

Objective: Triple signal (TS) is a subclinical lesion were found in the common carotid artery of individuals with renal fibromuscular dysplasia (FMD), However, the mechanisms underlying this alteration in FMD patients are still unknown and might involve endothelial and/or smooth muscle cell dysfunction. We aimed at investigated whether FMD or triple signal, is associated with systemic vascular dysfunction. Design and method: The MEDYA study is a case-control, cross-sectional study, enrolling 47 individuals with renal FMD,47 matched individuals with essential hypertension (HT) and 50 healthy controls (C). All individuals underwent an assessment of endothelium-dependent dilation (EDD) of the brachial artery by the flow-mediated dilation technique and endothelium-independent dilation (EID) by sublingual administration of glyceryl trinitrate 150 mcg. EDD and EID were allometrically corrected for baseline diameter. Triple signal score was also computed in the common carotid arteries bilaterally, based on B-mode and RF images. A cut-off of 8 was used to discriminate TS carriers. Results: FMD, but not HT, showed impaired EID in comparison to controls (p = 0.003). FMD (but not TS) was among the determinants of EID_corr in a multiple linear regression model (beta = −0.03, p = 0.005). TS prevalence (FMD 48.9%, HT 31.9%, C 16.0%) was higher in FMD than in C (p < 0.001), but tended to be increased in HT as well (p = 0.07). In a multiple logistic regression model adjusted for confounders, FMD (OR 4.54, CL95% 1.56–13.23) but not HT, was independently associated with TS. In the FMD subgroup, TS was associated with older age, higher peak shear stress and lower EDD. EDD was still reduced in FMD patients with TS after correction for confounders (1.14 ± 3.59 vs 3.55 ± 4.18, p = 0035). In the HT subgroup, TS was independently associated only with older age and hypercholesterolemia. Conclusions: FMD is characterized by impaired smooth muscle cell function and increased TS prevalence, subclinical alterations independent from each other. TS might have a different pathophysiological significance in FMD and HT. Indeed, among FMD patients TS is associated with impaired endothelial function. Conversely, in HT TS seems to be associated only with classical CV risk factors.

Role of Chronic Stress and Exercise on Microvascular Function in Metabolic Syndrome

The present study examined the effect of unpredictable chronic mild stress (UCMS) on peripheral microvessel function in healthy and metabolic syndrome (MetS) rodents and whether exercise training could prevent the vascular dysfunction associated with UCMS. Lean and obese (model of MetS) Zucker rats (LZR and OZR) were exposed to 8 wk of UCMS, exercise (Ex), UCMS + Ex, or control conditions. At the end of the intervention, gracilis arterioles (GA) were isolated and hung in a pressurized myobath to assess endothelium-dependent (EDD) and endothelium-independent (EID) dilation. Levels of nitric oxide (NO) and reactive oxygen species (ROS) were measured through 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate and dihydroethidium staining, respectively. Compared with LZR controls, EDD and EID were lower (P = 0.0001) in LZR-UCMS. The OZR-Ex group had a higher EDD (P = 0.0001) and EID (P = 0.003) compared with OZR controls, whereas only a difference in EDD (P = 0.01) was noted between the LZR-control and LZR-Ex groups. Importantly, EDD and EID were higher in the LZR (P = 0.0001; P = 0.02) and OZR (P = 0.0001; P = 0.02) UCMS + Ex groups compared with UCMS alone. Lower NO bioavailability and higher ROS were noted in the LZR-UCMS group (P = 0.0001), but not OZR-UCMS, compared with controls. The Ex and UCMS-Ex groups had higher NO bioavailability (P = 0.0001) compared with the control and UCMS groups, but ROS levels remained high. The comorbidity between UCMS and MetS does not exacerbate the effects of one another on GA EDD responses, but does lead to the development of other vasculopathy adaptations, which can be partially explained by alterations in NO and ROS production. Importantly, exercise training alleviates most of the negative effects of UCMS on GA function.

Impairment of Protease-Activated Receptor 2-Induced Relaxation of Aortas of Aged Spontaneously Hypertensive Rat.

Hypertension is one of the most prevalent diseases worldwide and can cause harmful complications within the vascular system. Further research on vascular responsiveness to different ligands and diverse receptors in various arteries is required to understand the mechanisms underlying the development of these vascular complications. Here, we investigated the vasorelaxant effect of the protease-activated receptor 2 (PAR2) agonist 2-furoyl-LIGRLO-amide (2-Fly) and two commonest agents, namely endothelium-dependent dilator acetylcholine (ACh) and endothelium-independent dilator sodium nitroprusside (SNP), on the thoracic aorta isolated from aged spontaneously hypertensive rats (SHR) (age, 52±1 weeks). The effects of these agents were compared between aortas isolated from SHR and age-matched normotensive Wistar Kyoto (WKY) rats. Compared with the WKY group, in the SHR group, 2-Fly-induced relaxation was impaired, ACh-induced relaxation was slightly decreased at low concentrations, and SNP-induced relaxation was similar. In addition, 2-Fly-induced aortic relaxation was largely decreased by a PAR2 antagonist (FSLLRY), endothelial denudation, and a nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine (L-NNA) but not by an Akt inhibitor. These results suggested that PAR2-induced relaxations of aortas of aged SHR was impaired, and this impaired aortic relaxation may be attributed to decreased NO bioavailability rather than altered NO sensitivity unrelated to the Akt activity.

Chronic Supplementation With a Mitochondrial Antioxidant (MitoQ) Improves Vascular Function in Healthy Older Adults.

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02597023.

Vascular wall regulator of G-protein signalling-1 (RGS-1) is required for angiotensin II–mediated blood pressure control

G-Protein coupled receptors (GPCRs) activate intracellular signalling pathways by coupling to heterotrimeric G-proteins that control many physiological processes including blood pressure homeostasis. The Regulator of G-Protein Signalling-1 (RGS1) controls the magnitude and duration of downstream GPCR signalling by acting as a GTPase-activating protein for specific Gα-proteins. RGS1 has contrasting roles in haematopoietic and non-haematopoietic cells. Rgs1−/−ApoE−/− mice are protected from Angiotensin II (Ang II)-induced aortic aneurysm rupture. Conversely, Ang II treatment increases systolic blood pressure to a greater extent in Rgs1−/−ApoE−/− mice than ApoE−/− mice, independent of its role in myeloid cells. However the precise role of RGS1 in hypertension and vascular-derived cells remains unknown. We determined the effects of Rgs1 deletion on vascular function in ApoE−/− mice. Rgs1 deletion led to enhanced vasoconstriction in aortas and mesenteric arteries from ApoE−/− mice in response to phenylephrine (PE) and U46619 respectively. Rgs1 was shown to have a role in the vasculature, with endothelium-dependent vasodilation being impaired, and endothelium-independent dilatation to SNP being enhanced in Rgs1−/−ApoE−/− mesenteric arteries. To address the downstream signalling pathways in vascular smooth muscle cells (VSMCs) in response to Ang II-stimulation, we assessed pErk1/2, pJNK and pp38 MAPK activation in VSMCs transiently transfected with Rgs1. pErk1/2 signalling but not pJNK and pp38 signalling was impaired in the presence of Rgs1. Furthermore, we demonstrated that the enhanced contractile response to PE in Rgs1−/−ApoE−/− aortas was reduced by a MAPK/Erk (MEK) inhibitor and an L-type voltage gated calcium channel antagonist, suggesting that Erk1/2 signalling and calcium influx are major effectors of Rgs1-mediated vascular contractile responses, respectively. These findings indicate RGS1 is a novel regulator of blood pressure homeostasis and highlight RGS1-controlled signalling pathways in the vasculature that may be new drug development targets for hypertension.

Associations of sex, age and adiposity in endothelium-independent dilation in children

Objective: To examine the association of age, sex, and obesity status on endothelial-independent dilation (EID) among children and adolescents. Study design: This study examined 264 children (143 males) between 8 to 18 years old (mean ± SD: age = 14.3 ± 2.7 years). Endothelial-independent dilation was assessed via ultrasound imaging of the brachial artery following administration of 0.3 milligrams of sublingual nitroglycerin. A one-way analysis of variance with Bonferroni post hoc comparisons assessed sex-differences in percent peak EID dilation (EID%-peak) and EID area under the curve (EID%-AUC), while analysis of covariance (ANCOVA) adjusted for race, age, body mass index percentile (BMI-percentile), and brachial artery diameter. Multiple linear regression evaluated the association of sex, age, BMI-percentile, percent body fat (%BF), and brachial artery diameter on EID. Results: Prior to adjustment, EID%-peak was significantly higher among females than males (mean ± SE: 26.9 ± 0.5% versus 22.9 ± 0.6%, p < 0.001, respectively); similar findings for EID%-AUC (4214% ± 105%·s versus 3398% ± 97%·s, p < 0.001) were observed. After adjusting for covariates, EID%-AUC remained consistent (p = 0.03) while EID%-peak was not significantly different between sexes (p = 0.21). EID%-peak was significantly higher among normal weight compared to obese participants (p = 0.04), while no differences were observed between obesity status after adjustment for brachial artery diameter (p = 0.64). Both unadjusted (p = 0.16) and adjusted EID%-AUC (p = 0.24) was not significantly different between obesity status. BMI-percentile was not associated with EID%-peak (p = 0.76) or EID%-AUC (p = 0.30). Additionally, %BF was not associated with EID%-peak (p = 0.56) or EID%-AUC (p = 0.15). After adjusting for brachial artery diameter, BMI-percentile, and age, males had lower EID%-AUC (p = 0.03) and lower but not significant EID%-peak (p = 0.21). Significance: Vascular smooth muscle function was significantly lower among male children and adolescents, which is suggestive that impaired EID and increased cardiovascular disease risk among males may begin in childhood. Interestingly, obesity status and BMI-percentile was not associated with EID in children and adolescents after adjusting for brachial artery diameter.

Mitochondrial‐Targeted Antioxidant (MitoQ) Improves Vascular Function in Healthy Late Middle‐Aged and Older Adults

Excess reactive oxygen species production by mitochondria (mtROS) is a key mechanism of vascular dysfunction with aging. Our laboratory has shown that supplementation with the mitochondrial‐targeted antioxidant MitoQ improves vascular endothelial function by reducing mtROS and ameliorates arterial stiffening in old mice, but the effects in humans are unknown. Here we sought to translate our preclinical findings to humans, while also determining the safety and efficacy of MitoQ. Twenty healthy late middle‐aged and older adults (60–79 years) with impaired endothelial function (baseline brachial artery flow‐mediated dilation [FMD] &lt;6%) underwent six weeks of oral supplementation with MitoQ (20 mg/day) or placebo in a randomized, placebo‐controlled, double‐blind, crossover design study. MitoQ was well tolerated, and no treatment‐related serious adverse events occurred. Plasma MitoQ concentrations were higher after the treatment vs. placebo period (P&lt;0.05). Brachial artery FMD was 42% higher after MitoQ vs. placebo (P&lt;0.05); this improvement was associated with complete amelioration of tonic mtROS‐related suppression of endothelial function (assessed as the increase in FMD with acute 160 mg dose of MitoQ, n=9, P&lt;0.05). Aortic stiffness (carotid‐femoral pulse wave velocity [PWV]) was lower after MitoQ vs. placebo (P&lt;0.05) in participants with elevated baseline levels (carotid‐femoral PWV &gt;7.60 m/s, n=11). Plasma oxidized low‐density lipoprotein, a marker of oxidative stress, also was lower after MitoQ vs. placebo (P&lt;0.05), whereas participant characteristics, endothelium‐independent dilation (sublingual nitroglycerin) and circulating markers of inflammation were not different (all P&gt;0.1). These findings in humans support earlier preclinical observations and suggest that MitoQ and other therapeutic strategies targeting mtROS may hold promise for treating age‐related vascular dysfunction.Support or Funding InformationClinicaltrials.gov Identifier: NCT02597023Funding: Supported by NIH R21 AG049451, T32 AG000279, F32 AG053009, Colorado CTSA UL1 TR001082 and an industry contract with MitoQ Limited.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Regular Aerobic, Resistance, and Cross-Training Exercise Prevents Reduced Vascular Function Following a High Sugar or High Fat Mixed Meal in Young Healthy Adults.

The postprandial state can negatively influence flow mediated dilation (FMD), a predictor of atherosclerosis and cardiovascular disease. This investigation was designed to determine the effect of regular aerobic and/or resistance exercise on postprandial FMD after a high sugar or high fat mixed meal. Forty-five healthy participants were recruited from one of four groups: lean sedentary (SED), runners, weight lifters, and cross-trainers. Participants were randomly crossed over to a high sugar meal (HSM) and a high fat mixed meal (HFMM; both fat and carbohydrate). Pre-and postprandial endothelial function was assessed for both meals using brachial artery FMD. Plasma lipids, insulin, glucose, hs-CRP, and SOD were also measured with both meals. Endothelium-independent dilation was determined via sublingual nitroglycerin. Brachial artery FMD was reduced in SED following the HSM (9.9 ± 0.9% at baseline, peak reduction at 60 min 6.5 ± 1.0%) and the HFMM (9.4 ± 0.9% at baseline, peak reduction at 120 min 5.9 ± 1.2%; P < 0.05 for both, Mean ± SEM). There was no change in FMD after either HSM or HFMM in runners, weight lifters, and cross-trainers. Post-prandial increases in blood glucose, insulin and triglycerides were less pronounced in the exercisers compared to SED. In addition, exercisers presented lower baseline plasma hs-CRP and higher SOD activity. Nitroglycerin responses were similar among groups. These results suggest that endothelial function is reduced in sedentary adults after a HSM or HFMM, but not in regular aerobic or resistance exercisers. This response may be due to favorable postprandial metabolic responses or lower postprandial levels of inflammation and oxidative stress. These findings may help to explain the cardioprotective effect of exercise.

Statins for endothelial dysfunction in sickle cell disease: A cohort study

Background: The sickling process of sickle cell disease (SCD) has harmful effects on the vascular endothelium manifested as vascular blockade, diminished tissue oxygenation, and consequently reperfusion injury. Statins pleiotropic effects can be demonstrated through improvement of endothelial function. Studies on the role of statins (e.g., atorvastatin) on endothelial dysfunction in SCD are minimal. Objective: The objective is to assess the possible therapeutic use of atorvastatin in patients with SCD. Subjects and Methods: Thirty SCD patients (15 female and 15 male) with a mean age of 27.0 ± 8.9 years and 30 healthy controls (18 female and 12 male) with a mean age of 29.7 ± 9.1 years participated in the study. Endothelial function was assessed with flow mediated dilatation (FMD) and endothelial independent dilatation (EID) of the brachial and common carotid arteries at baseline and after 6 weeks therapy with atorvastatin, 20 mg/day. Results: SCD patients had diminished FMD% and EID% values compared with corresponding values in the controls. The values were improved significantly after atorvastatin treatment (P = 0.002 for FMD%; P = 0.001 for EDI%). Conclusion: SCD patients have endothelial dysfunction. Atorvastatin, 20 mg daily for 6 weeks, improved the markers of endothelial function, FMD%, and EID%, in these patients.