Advanced glycated end-products inhibit dilation through constitutive endothelial RAGE and Nox1/4 in rat isolated skeletal muscle arteries.

OBJECTIVE: This study investigated the actions of advanced glycated end-products (AGE), their receptors (RAGE), and NAD(P)H oxidase (Nox) subtypes 1, 2, and 4 on mechanisms of endothelium-dependent dilation of the rat cremaster muscle artery (CMA). METHODS: Immunofluorescence studies were used to examine expression of RAGE in rat arteries. ROS accumulation was measured using luminescence and fluorescence assays. Functional studies were performed using pressure myography. RESULTS: High levels of RAGE expression were shown in the endothelial cells of the CMA, compared with low endothelial expression in middle cerebral and mesenteric arteries and the aorta. Exogenous AGE (in vitro glycated bovine serum albumin) stimulated H2O2 accumulation in CMA, which was prevented by the RAGE antagonist FPS-ZM1, the NAD(P)H oxidase (Nox) inhibitor apocynin and inhibited by the Nox1/4 inhibitor setanaxib, but not the Nox2 inhibitor GSK2795039. In functional studies, AGE inhibited vasodilation of CMA stimulated by acetylcholine, sodium nitroprusside, and the BKCa activator NS1619, but not adenosine-induced dilation. FPS-ZM1, apocynin, and setanaxib prevented the inhibitory effects of AGE on responses to acetylcholine and NS-1619. CONCLUSION: These observations suggest RAGE are constitutively expressed in the endothelium of the rat CMA and may be activated by AGE to stimulate Nox1/4 and ROS formation with resulting inhibition of NO and BKCa-mediated endothelium-dependent dilation.

Apigenin restores endothelial function by ameliorating oxidative stress, reverses aortic stiffening, and mitigates vascular inflammation with aging.

We assessed the efficacy of oral supplementation with the flavanoid apigenin on arterial function during aging and identified critical mechanisms of action. Young (6 mo) and old (27 mo) C57BL/6N mice (model of arterial aging) consumed drinking water containing vehicle (0.2% carboxymethylcellulose; 10 young and 7 old) or apigenin (0.5 mg/mL in vehicle; 10 young and 9 old) for 6 wk. In vehicle-treated animals, isolated carotid artery endothelium-dependent dilation (EDD), bioassay of endothelial function, was impaired in old versus young (70% ± 9% vs. 92% ± 1%, P < 0.0001) due to reduced nitric oxide (NO) bioavailability. Old mice had greater arterial reactive oxygen species (ROS) production and oxidative stress (higher nitrotyrosine) associated with greater nicotinamide adenine dinucleotide phosphate oxidase (oxidant enzyme) and lower superoxide dismutase 1 and 2 (antioxidant enzymes); ex vivo administration of Tempol (antioxidant) restored EDD to young levels, indicating ROS-mediated suppression of EDD. Old animals also had greater aortic stiffness as indicated by higher aortic pulse wave velocity (PWV, 434 ± 9 vs. 346 ± 5 cm/s, P < 0.0001) due to greater intrinsic aortic wall stiffness associated with lower elastin levels and higher collagen, advanced glycation end products (AGEs), and proinflammatory cytokine abundance. In old mice, apigenin restored EDD (96% ± 2%) by increasing NO bioavailability, normalized arterial ROS, oxidative stress, and antioxidant expression, and abolished ROS inhibition of EDD. Moreover, apigenin prevented foam cell formation in vitro (initiating step in atherosclerosis) and mitigated age-associated aortic stiffening (PWV 373 ± 5 cm/s) by normalizing aortic intrinsic wall stiffness, collagen, elastin, AGEs, and inflammation. Thus, apigenin is a promising therapeutic for arterial aging.NEW & NOTEWORTHY Our study provides novel evidence that oral apigenin supplementation can reverse two clinically important indicators of arterial dysfunction with age, namely, vascular endothelial dysfunction and large elastic artery stiffening, and prevents foam cell formation in an established cell culture model of early atherosclerosis. Importantly, our results provide extensive insight into the biological mechanisms of apigenin action, including increased nitric oxide bioavailability, normalization of age-related increases in arterial ROS production and oxidative stress, reversal of age-associated aortic intrinsic mechanical wall stiffening and adverse remodeling of the extracellular matrix, and suppression of vascular inflammation. Given that apigenin is commercially available as a dietary supplement in humans, these preclinical findings provide the experimental basis for future translational studies assessing the potential of apigenin to treat arterial dysfunction and reduce cardiovascular disease risk with aging.

Hydrogen sulfide-dependent microvascular vasodilation is improved following chronic sulfhydryl-donating antihypertensive pharmacotherapy in adults with hypertension.

Hypertension is characterized by systemic microvascular endothelial dysfunction, in part due to a functional absence of hydrogen sulfide (H2S)-mediated endothelium-dependent dilation. Treatment with a sulfhydryl-donating ACE inhibitor (SH-ACE inhibitor) improves endothelial function in preclinical models of hypertension. To date, no studies have directly assessed the effects of SH-ACE-inhibitor treatment on H2S-dependent vasodilation in humans with hypertension. We hypothesized that SH-ACE-inhibitor treatment would improve H2S-mediated endothelium-dependent vasodilation. Ten adults with hypertension [1 woman and 9 men; 56 ± 9 yr; systolic blood pressure (SBP): 141 ± 8.5 mmHg; diastolic blood pressure (DBP): 90.3 ± 6 mmHg] were treated (16 wk) with the SH-ACE-inhibitor captopril. Red blood cell flux (laser-Doppler flowmetry) was measured continuously during graded intradermal microdialysis perfusion of the endothelium-dependent agonist acetylcholine (ACh; 10-10 to 10-1 M) alone (control) and in combination with an inhibitor of enzymatic H2S production [10-3 M aminooxyacetate (AOAA)] preintervention and postintervention. Cutaneous vascular conductance (CVC; flux/mmHg) was calculated and normalized to the site-specific maximal CVC (0.028 M sodium nitroprusside and local heat to 43°C). Area under the curve was calculated using the trapezoid method. The 16-wk SH-ACE-inhibitor treatment resulted in a reduction of blood pressure (systolic BP: 129 ± 10 mmHg; diastolic BP: 81 ± 9 mmHg, both P < 0.05). Preintervention, inhibition of H2S production had no effect on ACh-induced vasodilation (316 ± 40 control vs. 322 ± 35 AU AOAA; P = 0.82). Captopril treatment improved ACh-induced vasodilation (316 ± 40 pre vs. 399 ± 55 AU post; P = 0.04) and increased the H2S-dependent component of ACh-induced vasodilation (pre: -6.6 ± 65.1 vs. post: 90.2 ± 148.3 AU, P = 0.04). These data suggest that SH-ACE-inhibitor antihypertensive treatment improves cutaneous microvascular endothelium-dependent vasodilation in adults with hypertension, in part via H2S-dependent mechanisms.NEW & NOTEWORTHY This is the first study to prospectively assess the effects of sulfhydryl antihypertensive treatment on microvascular endothelial function in adults with hypertension. Our data suggest that 16 wk of SH-ACE-inhibitor antihypertensive treatment improves cutaneous microvascular endothelium-dependent vasodilation in middle-aged adults with hypertension, in part via H2S-dependent mechanisms.

AHA/ACC-defined stage 1 hypertensive adults do not display cutaneous microvascular endothelial dysfunction.

In 2017, the American Heart Association (AHA) and American College of Cardiology (ACC) redefined stage 1 hypertension to systolic blood pressure (BP) 130-139 mmHg or diastolic BP 80-89 mmHg; however, the degree to which microvascular endothelial dysfunction is evident in adults with stage 1 hypertension remains equivocal. We tested the hypotheses that cutaneous microvascular endothelial dysfunction would be present in adults with stage 1 hypertension (HTN1) compared with normotensive adults (NTN; BP <120/<80 mmHg) but would be less severe compared with adults with stage 2 hypertension (HTN2; systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg) and that this graded impairment would be mediated by reductions in nitric oxide (NO)-dependent dilation. This retrospective analysis included 20 NTN (5 men; 45-64 yr; BP 94-114/60-70 mmHg), 22 HTN1 (11 men; 40-74 yr; BP 110-134/70-88 mmHg), and 44 HTN2 (27 men; 40-74 yr; BP 128-180/80-110 mmHg). BP and nocturnal dipping status were also assessed using 24-h ambulatory BP monitoring. Red cell flux (laser Doppler flowmetry) was measured during intradermal microdialysis perfusion of acetylcholine (ACh; 10-10 to 10-1M) alone and concurrently with the nonspecific nitric oxide (NO) synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 15 mM). ACh-induced dilation was impaired in HTN2 (P < 0.01), but not in HTN1 (P = 0.85), compared with NTN. Furthermore, reductions in NO-dependent dilation were evident in HTN2 (P < 0.01) but not in HTN1 (P = 0.76). Regardless of BP, endothelium-dependent dilation was impaired in nondippers (nighttime drop in systolic BP <10%) compared with dippers (nighttime drop in systolic BP ≥10%, P < 0.05). In conclusion, functional impairments in NO-mediated endothelium-dependent dilation were not evident in HTN1. However, regardless of BP classification, the lack of a nocturnal dip in BP was associated with blunted endothelium-dependent dilation.NEW & NOTEWORTHY This is the first study to pharmacologically assess the mechanistic regulation of endothelial function in adults with hypertension, classified according to the 2017 clinical guidelines set for by the American Heart Association (AHA) and American College of Cardiology (ACC). Compared with that in normotensive adults, nitric oxide-mediated endothelium-dependent dilation is impaired in adults with stage 2, but not stage 1, hypertension. Adults lacking a nighttime dip in blood pressure demonstrated reductions in endothelium-dependent dilation.

Local endothelial DNA repair deficiency causes aging-resembling endothelial-specific dysfunction.

We previously identified genomic instability as a causative factor for vascular aging. In the present study, we determined which vascular aging outcomes are due to local endothelial DNA damage, which was accomplished by genetic removal of ERCC1 (excision repair cross-complementation group 1) DNA repair in mice (EC-knockout (EC-KO) mice). EC-KO showed a progressive decrease in microvascular dilation of the skin, increased microvascular leakage in the kidney, decreased lung perfusion, and increased aortic stiffness compared with wild-type (WT). EC-KO showed expression of DNA damage and potential senescence marker p21 exclusively in the endothelium, as demonstrated in aorta. Also the kidney showed p21-positive cells. Vasodilator responses measured in organ baths were decreased in aorta, iliac and coronary artery EC-KO compared with WT, of which coronary artery was the earliest to be affected. Nitric oxide-mediated endothelium-dependent vasodilation was abolished in aorta and coronary artery, whereas endothelium-derived hyperpolarization and responses to exogenous nitric oxide (NO) were intact. EC-KO showed increased superoxide production compared with WT, as measured in lung tissue, rich in endothelial cells (ECs). Arterial systolic blood pressure (BP) was increased at 3 months, but normal at 5 months, at which age cardiac output (CO) was decreased. Since no further signs of cardiac dysfunction were detected, this decrease might be an adaptation to prevent an increase in BP. In summary, a selective DNA repair defect in the endothelium produces features of age-related endothelial dysfunction, largely attributed to loss of endothelium-derived NO. Increased superoxide generation might contribute to the observed changes affecting end organ perfusion, as demonstrated in kidney and lung.

Transient receptor potential vanilloid 4 channels are important regulators of parenchymal arteriole dilation and cognitive function.

OBJECTIVE: Hypertension-associated PA dysfunction reduces cerebral perfusion and impairs cognition. This is associated with impaired TRPV4-mediated PA dilation; therefore, we tested the hypothesis that TRPV4 channels are important regulators of cerebral perfusion, PA structure and dilation, and cognition. METHODS: Ten- to twelve-month-old male TRPV4 knockout (WKY-Trpv4em4Mcwi ) and age-matched control WKY rats were studied. Cerebral perfusion was measured by MRI with arterial spin labeling. PA structure and function were assessed using pressure myography and cognitive function using the novel object recognition test. RESULTS: Cerebral perfusion was reduced in the WKY-Trpv4em4Mcwi rats. This was not a result of PA remodeling because TRPV4 deletion did not change PA structure. TRPV4 deletion did not change PA myogenic tone development, but PAs from the WKY-Trpv4em4Mcwi rats had severely blunted endothelium-dependent dilation. The WKY-Trpv4em4Mcwi rats had impaired cognitive function and exhibited depressive-like behavior. The WKY-Trpv4em4Mcwi rats also had increased microglia activation, and increased mRNA expression of GFAP and tumor necrosis factor alpha suggesting increased inflammation. CONCLUSION: Our data indicate that TRPV4 channels play a critical role in cerebral perfusion, PA dilation, cognition, and inflammation. Impaired TRPV4 function in diseases such as hypertension may increase the risk of the development of vascular dementia.

Bilateral common carotid artery stenosis in normotensive rats impairs endothelium-dependent dilation of parenchymal arterioles.

Chronic cerebral hypoperfusion is a risk factor for cognitive impairment. Reduced blood flow through the common carotid arteries induced by bilateral carotid artery stenosis (BCAS) is a physiologically relevant model of chronic cerebral hypoperfusion. We hypothesized that BCAS in 20-wk-old Wistar-Kyoto (WKY) rats would impair cognitive function and lead to reduced endothelium-dependent dilation and outward remodeling in the parenchymal arterioles (PAs). After 8 wk of BCAS, both short-term memory and spatial discrimination abilities were impaired. In vivo assessment of cerebrovascular reserve capacity showed a severe impairment after BCAS. PA endothelial function and structure were assessed by pressure myography. BCAS impaired endothelial function in PAs, as evidenced by reduced dilation to carbachol. Addition of nitric oxide synthase and cyclooxygenase inhibitors did not change carbachol-mediated dilation in either group. Inhibiting CYP epoxygenase, the enzyme that produces epoxyeicosatrienoic acid (EETs), a key determinant of endothelium-derived hyperpolarizing factor (EDHF)-mediated dilation, abolished dilation in PAs from Sham rats, but had no effect in PAs from BCAS rats. Expression of TRPV4 channels, a target for EETs, was decreased and maximal dilation to a TRPV4 agonist was attenuated after BCAS. Together these data suggest that EET-mediated dilation is impaired in PAs after BCAS. Thus impaired endothelium-dependent dilation in the PAs may be one of the contributing factors to the cognitive impairment observed after BCAS.

DOCA-salt hypertension impairs artery function in rat middle cerebral artery and parenchymal arterioles.

OBJECTIVE: Chronic hypertension induces detrimental changes in the structure and function of surface cerebral arteries. Very little is known about PAs, which perfuse distinct neuronal populations in the cortex and may play a role in cerebrovascular disorders. We investigated the effect of DOCA-salt induced hypertension on endothelial function and artery structure in PAs and MCAs. METHODS: Uninephrectomized male Sprague-Dawley rats were implanted with a subcutaneous pellet containing DOCA (150 mg/kg b.w.) and drank salt water (1% NaCl and 0.2% KCl) for 4 weeks. Sham rats were uninephrectomized and drank tap water. Vasoreactivity and passive structure in the MCAs and the PAs were assessed by pressure myography. RESULTS: Both MCAs and PAs from DOCA-salt rats exhibited impaired endothelium-dependent dilation (P<.05). In the PAs, addition of NO and COX inhibitors enhanced dilation in DOCA-salt rats (P<.05), suggesting that dysfunctional NO and COX-dependent signaling could contribute to impaired endothelium-mediated dilation. MCAs from DOCA-salt rats exhibited inward remodeling (P<.05). CONCLUSIONS: Hypertension-induced MCA remodeling coupled with impaired endothelium-dependent dilation in both the MCAs and PAs may exacerbate the risk of cerebrovascular accidents and the associated morbidity and mortality.

Association of the Glu504Lys polymorphism in the aldehyde dehydrogenase 2 gene with endothelium-dependent dilation disorder in Chinese Han patients with essential hypertension.

BACKGROUND: In essential hypertension (EH), 30-50% of the variability in blood pressure is determined by genetic factors. The aldehyde dehydrogenase 2 (ALDH2) gene Glu504Lys polymorphism is associated with 'alcohol flush' and might be associated with EH. AIMS: The aim of the present study was to investigate the association of the Glu504Lys polymorphism in the ALDH2 gene with endothelium-dependent dilation (EDD) disorder in Chinese Han patients with EH. METHODS: This case-control study enrolled 1210 patients with EH. The control group consisted of 1089 healthy subjects with normal blood pressure. Patients with EH were divided into normal brachial arterial flow-mediated dilation (FMD) (EH1 group, n = 354) versus endothelial dysfunction (EH2 group, n = 856). ALDH2 gene Glu504Lys polymorphism was detected using a DNA microarray. RESULTS: The ALDH2 AA/AG genotypes and the A allele frequencies were significantly higher in the EH group compared with healthy controls (both P < 0.05) and significantly higher in the EH2 group compared with the EH1 group (79.8 vs 51.4%; 45.0 vs 29.1%, respectively; both P < 0.05). Multivariate logistic regression analyses showed that the ALDH2 gene Glu504Lys polymorphism was independently associated with EH (dominant: odds ratio (OR) = 1.38; 95% confidence interval (95% CI) = 1.14-2.82; P = 0.01; additive: OR = 1.32; 95% CI = 1.12-2.44; P = 0.02) as well as with EDD in patients with EH (dominant: OR = 1.49, 95% CI = 1.16-3.01, P = 0.02; additive: OR = 1.43, 95% CI = 1.10-2.87, P = 0.03). CONCLUSION: The ALDH2 Glu504Lys polymorphism was associated with EDD disorders in Chinese Han patients with EH, providing further evidence that this mutation and 'alcohol flush' are not harmless in this Asian population.

Aging alters reactivity of microvascular resistance networks in mouse gluteus maximus muscle.

Aging occurs with enhanced sympathetic nerve activity and endothelial dysfunction; however, little is known of how successive branches of microvascular resistance networks are affected in vivo. We questioned whether vascular reactivity is altered differentially along resistance networks with advanced age. The left gluteus maximus muscle of anesthetized 4-mo-old and 24-mo-old male C57BL/6 mice (Young and Old, respectively) was exposed for intravital microscopy and superfused with physiological salt solution (3 ml/min; pH 7.4, 34°C). Spontaneous vasomotor tone increased progressively from proximal feed arteries (FA) and first-order (1A) arterioles through distal second-order (2A) and third-order (3A) arterioles and was ~15% greater in 2A and 3A of Old versus Young. Vasoconstriction during elevated superfusion Po2 increased with branch order and to a greater extent in Young. Peak constrictions to phenylephrine [α1 adrenoreceptor (α1AR) agonist] were similar for FA and 1A of both ages and ~20% greater for 2A and 3A of Young. Across arterioles (but not FA), constrictions to UK 14304 (α2AR agonist) were depressed ~30% in Old versus Young. Thus advanced age attenuated vasoconstriction to O2 throughout networks while blunting vasoconstriction to α1AR and α2AR activation in arterioles. With ACh, endothelium-dependent dilation (EDD) was ~20% greater in FA of Young yet was approximately twofold greater for 2A and 3A of Old. Sodium nitroprusside evoked maximal dilations similar to ACh. Thus, with advanced age, EDD was attenuated in FA while robust in distal arterioles having enhanced vasomotor tone. We conclude that advanced age differentially alters reactivity among branches of microvascular resistance networks.

Pressure-induced maturation of endothelial cells on newborn mouse carotid arteries.

Experiments investigated maturation of endothelial function in the postnatal period. Carotid arteries isolated from newborn (postnatal day 1, P1) to P21 mice were assessed in myographs at transmural pressure (PTM) of 20 mmHg (P1 blood pressure, BP). Acetylcholine was ineffective in P1 but powerfully dilated P7 arteries, whereas NO-donor DEA-NONOate caused similar dilation at P1 and P7. Dilation to acetylcholine at P7 was abolished by inhibition of NO synthase (NOS) (l-NAME) or of phosphoinositide-3-kinase (PI3K) (wortmannin, LY294002). Endothelial NOS (eNOS) expression decreased in P7 compared with P1 arteries, although acetylcholine increased PO4-eNOS-Ser(1177) in P7 but not in P1 arteries. Endothelial maturation may therefore reflect increased signaling through PI3K, Akt, and eNOS. Systemic BP increases dramatically in the early postnatal period. After exposing P1 arteries to transient increased PTM (50 mmHg, 60 min), acetylcholine caused powerful dilation and increased PO4-eNOS-Ser(1177). Pressure-induced rescue of acetylcholine dilation was abolished by PI3K or NOS inhibition. Transient increased PTM did not affect dilation at P7, or dilation to NO-donor in P1 arteries. Width of endothelial adherens junctions (VE-cadherin immunofluorescence) increased significantly from P1 to P7, and in P1 arteries exposed to transient increased PTM. A function-blocking antibody to VE-cadherin reduced the pressure-induced rescue of acetylcholine responses at P1, and the dilation to acetylcholine in P7 arteries. Therefore, maturation of newborn endothelium dilator function may be induced by increasing BP in the postnatal period. Furthermore, this may be mediated by VE-cadherin signaling at adherens junctions. Interruption of this maturation pathway may contribute to developmental and adult vascular diseases.

Amyloid-ß disrupts unitary calcium entry through endothelial NMDA receptors in mouse cerebral arteries.

Transient increases in intracellular Ca2+ activate endothelium-dependent vasodilatory pathways. This process is impaired in cerebral amyloid angiopathy, where amyloid-ß(1-40) accumulates around blood vessels. In neurons, amyloid-ß impairs the Ca2+-permeable N-methyl-D-aspartate receptor (NMDAR), a mediator of endothelium-dependent dilation in arteries. We hypothesized that amyloid-ß(1-40) reduces NMDAR-elicited Ca2+ signals in mouse cerebral artery endothelial cells, blunting dilation. Cerebral arteries isolated from 4-5 months-old, male and female cdh5:Gcamp8 mice were used for imaging of unitary Ca2+ influx through NMDAR (NMDAR sparklets) and intracellular Ca2+ transients. The NMDAR agonist NMDA (10 µmol/L) increased frequency of NMDAR sparklets and intracellular Ca2+ transients in endothelial cells; these effects were prevented by NMDAR antagonists D-AP5 and MK-801. Next, we tested if amyloid-ß(1-40) impairs NMDAR-elicited Ca2+ transients. Cerebral arteries incubated with amyloid-ß(1-40) (5 µmol/L) exhibited reduced NMDAR sparklets and intracellular Ca2+ transients. Lastly, we observed that NMDA-induced dilation of pial arteries is reduced by acute intraluminal amyloid-ß(1-40), as well as in a mouse model of Alzheimer's disease, the 5x-FAD, linked to downregulation of Grin1 mRNA compared to wild-type littermates. These data suggest that endothelial NMDAR mediate dilation via Ca2+-dependent pathways, a process disrupted by amyloid-ß(1-40) and impaired in 5x-FAD mice.

Preserved cardiovascular homeostasis despite blunted acetylcholine-induced dilation in mice with endothelial muscarinic M3 receptor deletion.

AIM: Muscarinic acetylcholine receptors (AChMR1-5) are fundamental for cellular responses upon release of the neurotransmitter acetylcholine (ACh) from parasympathetic nerve fibers. ACh is the prototypical agonist stimulating endothelium-dependent dilation, but most blood vessels lack parasympathetic innervation, raising the question as to the physiologic function of endothelial AChMR in vivo. Global deletion of AChM3R revealed a role in ACh-induced vasodilation in vitro and food uptake, but overall cardiovascular homeostasis has not been examined thoroughly. METHODS: To characterize the function of endothelial AChM3R in vivo, we deleted AChM3R specifically in endothelial cells with an inducible or a non-inducible Cre-loxP system, driven by the endothelium-specific promoters VE-cadherin (indEC-M3R-/- ) or TIE2 (tek2; EC-M3R-/- ) and examined arteriolar dilation in the cremaster microcirculation, arterial pressure and cardiac function in these mice in vivo. RESULTS: In both EC-M3R-/- , ACh-induced dilation was strongly impaired in arterioles in vivo, while responses to other dilators were mostly preserved. However, arterial pressure (indEC-M3R-/- ) and arteriolar tone as a surrogate for peripheral vascular resistance did not differ between EC-M3R-/- and control mice. Aged EC-M3R-/- mice (74-78 weeks) did not differ in body weight, heart weight, cardiac structure or contractile function from controls. CONCLUSION: We conclude that AChM3R elicits the endothelium-dependent dilation upon ACh also in arterioles in vivo. Despite this prominent role, the endothelial deletion of AChM3R does not affect overall cardiovascular homeostasis. Thus, their physiologic function in endothelial cells remains obscure.

Endothelium-dependent responses in the microcirculation observed in vivo.

Endothelium-dependent responses were first demonstrated 40 years ago in the aorta. Since then, extensive research has been conducted in vitro using conductance vessels and materials derived from them. However, the microcirculation controls blood flow to vital organs and has been the focus of in vivo studies of endothelium-dependent dilation beginning immediately after the first in vitro report. Initial in vivo studies employed a light/dye technique for selectively damaging the endothelium to unequivocally prove, in vivo, the existence of endothelium-dependent dilation and in the microvasculature. Endothelium-dependent constriction was similarly proven. Endothelium-dependent agonists include acetylcholine (ACh), bradykinin, arachidonic acid, calcium ionophore A-23187, calcitonin gene-related peptide (CGRP), serotonin, histamine and endothelin-1. Normal and disease states have been studied. Endothelial nitric oxide synthase, cyclooxygenase and cytochrome P450 have been shown to generate the mediators of the responses. Some of the key enzyme systems generate reactive oxygen species (ROS) like superoxide which may prevent EDR. However, one ROS, namely H2 O2 , is one of a number of hyperpolarizing factors that cause dilation initiated by endothelium. Depending upon microvascular bed, a single agonist may use different pathways to elicit an endothelium-dependent response. Interpretation of studies using inhibitors of eNOS is complicated by the fact that these inhibitors may also inhibit ATP-sensitive potassium channels. Other in vivo observations of brain arterioles failed to establish nitric oxide as the mediator of responses elicited by CGRP or by ACh and suggest that a nitrosothiol may be a better fit for the latter.

Neuroprotective effects of TRPA1 channels in the cerebral endothelium following ischemic stroke.

Hypoxia and ischemia are linked to oxidative stress, which can activate the oxidant-sensitive transient receptor potential ankyrin 1 (TRPA1) channel in cerebral artery endothelial cells, leading to vasodilation. We hypothesized that TRPA1 channels in endothelial cells are activated by hypoxia-derived reactive oxygen species, leading to cerebral artery dilation and reduced ischemic damage. Using isolated cerebral arteries expressing a Ca2+ biosensor in endothelial cells, we show that 4-hydroxynonenal and hypoxia increased TRPA1 activity, detected as TRPA1 sparklets. TRPA1 activity during hypoxia was blocked by antioxidants and by TRPA1 antagonism. Hypoxia caused dilation of cerebral arteries, which was disrupted by antioxidants, TRPA1 blockade and by endothelial cell-specific Trpa1 deletion (Trpa1 ecKO mice). Loss of TRPA1 channels in endothelial cells increased cerebral infarcts, whereas TRPA1 activation with cinnamaldehyde reduced infarct in wildtype, but not Trpa1 ecKO, mice. These data suggest that endothelial TRPA1 channels are sensors of hypoxia leading to vasodilation, thereby reducing ischemic damage.

Cardiovascular Risk Markers and Major Adverse Cardiovascular Events in Psoriatic Arthritis Patients.

BACKGROUND: Psoriatic arthritis is a chronic inflammatory arthropathy that affects 14%- 30% of patients with skin and/or nail psoriasis, leading to severe physical limitations and disability. It has been included in the group of spondyloarthropathy with which it shares clinical, radiologic, and serologic features in addition to familial and genetic relationship. Beyond skin and joint involvement, psoriatic arthritis is characterized by a high prevalence of extra-articular manifestation and comorbidities, such as autoimmune, infectious and neoplastic diseases. In particular, an increased risk of cardiovascular comorbidity has been observed in psoriatic arthritis patients. METHODS: A systematic search was performed in the electronic databases (PubMed, Web of Science, Scopus, EMBASE) up until January 2017. Studies were included if they contained data on CV disease and/or risk factors in PsA and each article was then reviewed for quality and clinical relevance. After completing the literature search all screened literature was summarized and discussed in our study group (CaRDDs study group). All literature and comments were included in the systematic review. RESULTS: The initial search produced 278 abstracts, which were narrowed to 83 potentially relevant articles by preliminary review of the titles and by excluding review articles and case report (n = 195). Thirty articles were deemed ineligible after examining the abstracts. Full texts of the remaining 53 articles were retrieved. The majority of articles excluded were due to only providing data on patients with psoriasis or due to being not relevant to the CV risk in PsA. In the end, 32 articles were deemed eligible for this review. CONCLUSION: Psoriatic arthritis appeared significantly associated with subclinical atherosclerosis and endothelial dysfunction and, in turn, with an increased cardiovascular risk. Thus, patients with psoriatic arthritis may benefit from a periodic assessment of surrogate markers of cardiovascular risk. This could help to establish more specific cardiovascular prevention strategies for these patients.

Habitual aerobic exercise does not protect against micro- or macrovascular endothelial dysfunction in healthy estrogen-deficient postmenopausal women.

Aging causes micro- and macrovascular endothelial dysfunction, as assessed by endothelium-dependent dilation (EDD), which can be prevented and reversed by habitual aerobic exercise (AE) in men. However, in estrogen-deficient postmenopausal women, whole forearm microvascular EDD has not been studied, and a beneficial effect of AE on macrovascular EDD has not been consistently shown. We assessed forearm blood flow in response to brachial artery infusions of acetylcholine (FBFACh), a measure of whole forearm microvascular EDD, and brachial artery flow-mediated dilation (FMD), a measure of macrovascular EDD, in 12 premenopausal sedentary women (Pre-S; 24 ± 1 yr; V̇o2max = 37.5 ± 1.6 ml·kg-1·min-1), 25 estrogen-deficient postmenopausal sedentary women (Post-S; 62 ± 1 yr; V̇o2max = 24.7 ± 0.9 ml·kg-1·min-1), and 16 estrogen-deficient postmenopausal AE-trained women (Post-AE; 59 ± 1 yr; V̇o2max = 40.4 ± 1.4 ml·kg-1·min-1). FBFACh was lower in Post-S and Post-AE compared with Pre-S women (135 ± 9 and 116 ± 17 vs. 193 ± 21 AUC, respectively, both P < 0.008), whereas Post-S and Post-AE women were not different (P = 0.3). Brachial artery FMD was 34% (5.73 ± 0.67%) and 45% (4.79 ± 0.57%) lower in Post-S and Post-AE, respectively, vs. Pre-S women (8.69 ± 0.95%, both P ≤ 0.01), but not different between Post-S and Post-AE women (P = 0.3). Post-AE women had lower circulating C-reactive protein and oxidized low-density lipoprotein compared with Post-S women (0.5 ± 0.1 vs. 1.1 ± 0.2 mg/l and 40 ± 4 vs. 55 ± 3 U/l, respectively, both P = 0.01), but these markers were not correlated to FBFACh (P = 0.3) or brachial artery FMD (P = 0.8). These findings are consistent with the idea that habitual AE does not protect against age/menopause-related whole forearm micro- and macrovascular endothelial dysfunction in healthy nonobese estrogen-deficient postmenopausal women, despite being associated with lower systemic markers of inflammation and oxidative stress. NEW & NOTEWORTHY: This is the first study to demonstrate that habitual aerobic exercise may not protect against age/menopause-related whole forearm microvascular endothelial dysfunction in healthy nonobese estrogen-deficient postmenopausal women, consistent with recent findings regarding macrovascular endothelial function. This is in contrast to what is observed in healthy middle-aged and older aerobic exercise-trained men.

Curcumin supplementation improves vascular endothelial function in healthy middle-aged and older adults by increasing nitric oxide bioavailability and reducing oxidative stress.

We hypothesized that curcumin would improve resistance and conduit artery endothelial function and large elastic artery stiffness in healthy middle-aged and older adults. Thirty-nine healthy men and postmenopausal women (45-74 yrs) were randomized to 12 weeks of curcumin (2000 mg/day Longvida®; n=20) or placebo (n=19) supplementation. Forearm blood flow response to acetylcholine infusions (FBFACh; resistance artery endothelial function) increased 37% following curcumin supplementation (107±13 vs. 84±11 AUC at baseline, P=0.03), but not placebo (P=0.2). Curcumin treatment augmented the acute reduction in FBFACh induced by the nitric oxide synthase inhibitor NG monomethyl-L-arginine (L-NMMA; P=0.03), and reduced the acute increase in FBFACh to the antioxidant vitamin C (P=0.02), whereas placebo had no effect (both P>0.6). Similarly, brachial artery flow-mediated dilation (conduit artery endothelial function) increased 36% in the curcumin group (5.7±0.4 vs. 4.4±0.4% at baseline, P=0.001), with no change in placebo (P=0.1). Neither curcumin nor placebo influenced large elastic artery stiffness (aortic pulse wave velocity or carotid artery compliance) or circulating biomarkers of oxidative stress and inflammation (all P>0.1). In healthy middle-aged and older adults, 12 weeks of curcumin supplementation improves resistance artery endothelial function by increasing vascular nitric oxide bioavailability and reducing oxidative stress, while also improving conduit artery endothelial function.

Impaired Hydrogen Sulfide-Mediated Vasodilation Contributes to Microvascular Endothelial Dysfunction in Hypertensive Adults.

Reductions in hydrogen sulfide (H2S) production have been implicated in the pathogenesis of vascular dysfunction in animal models of hypertension; however, no studies have examined a functional role for H2S in contributing to microvascular dysfunction in hypertensive (HTN) adults. We hypothesized that endogenous production of H2S would be reduced, impaired endothelium-dependent vasodilation would be mediated by reductions in H2S-dependent vasodilation, and vascular responsiveness to exogenous H2S (sodium sulfide) would be attenuated in HTN compared to normotensive adults. Fifteen normotensive (51±2 years; blood pressure, 116±3/76±3 mm Hg) and 14 HTN adults (57±2 years; blood pressure 140±3/89±2 mm Hg) participated. H2S biosynthetic enzyme expression (Western blot) and substrate-dependent H2S production (amperometric probe) were measured in cutaneous tissue homogenates. Red cell flux (laser Doppler flowmetry) was measured during graded perfusions of acetylcholine (ACh; 10-6-10-1 mol/L) and sodium sulfide (10-5-101 mol/L) using intradermal microdialysis; the functional role of H2S was determined using pharmacological inhibition with aminooxyacetic acid (0.5 mmol/L). H2S biosynthetic enzyme expression and substrate-dependent H2S production were reduced in HTN adults (all P<0.05). ACh-induced endothelium-dependent vasodilation was blunted in HTN adults (P=0.012). Aminooxyacetic acid attenuated ACh-induced vasodilation in normotensive adults (ACh, 1.31±0.13 versus ACh+aminooxyacetic acid, 1.07±0.09 flux/mm Hg; P=0.025) but had no effect on vasodilation in HTN adults (ACh, 1.16±0.10 versus ACh+aminooxyacetic acid, 1.37±0.11 flux/mm Hg; P=0.47). Sodium sulfide-induced vasodilation was not different between groups. Collectively, these findings indicate that while the microvasculature maintains the ability to vasodilate in response to exogenous H2S, reductions in endogenous synthesis and H2S-dependent vasodilation contribute to endothelial dysfunction in human hypertension.

Oral trehalose supplementation improves resistance artery endothelial function in healthy middle-aged and older adults.

We hypothesized that supplementation with trehalose, a disaccharide that reverses arterial aging in mice, would improve vascular function in middle-aged and older (MA/O) men and women. Thirty-two healthy adults aged 50-77 years consumed 100 g/day of trehalose (n=15) or maltose (n=17, isocaloric control) for 12 weeks (randomized, double-blind). In subjects with Δbody mass less than 2.3kg (5 lb.), resistance artery endothelial function, assessed by forearm blood flow to brachial artery infusion of acetylcholine (FBFACh), increased ~30% with trehalose (13.3±1.0 vs. 10.5±1.1 AUC, P=0.02), but not maltose (P=0.40). This improvement in FBFACh was abolished when endothelial nitric oxide (NO) production was inhibited. Endothelium-independent dilation, assessed by FBF to sodium nitroprusside (FBFSNP), also increased ~30% with trehalose (155±13 vs. 116±12 AUC, P=0.03) but not maltose (P=0.92). Changes in FBFACh and FBFSNP with trehalose were not significant when subjects with Δbody mass ≥ 2.3kg were included. Trehalose supplementation had no effect on conduit artery endothelial function, large elastic artery stiffness or circulating markers of oxidative stress or inflammation (all P>0.1) independent of changes in body weight. Our findings demonstrate that oral trehalose improves resistance artery (microvascular) function, a major risk factor for cardiovascular diseases, in MA/O adults, possibly through increasing NO bioavailability and smooth muscle sensitivity to NO.