Elevated endothelin-1 vasoconstrictor tone in prehypertensive adults

Effect of endothelin-1 on the blood pressure response to acute hypoxia and hyperoxia in healthy young men

Endothelin-1 (ET-1) and its receptors are linked to increases in sensitivity of the chemoreceptors to hypoxic stress and the development of hypertension in preclinical models. We hypothesized ET receptor antagonism would lower resting blood pressure (BP) as well as the acute BP response to chemoreflex stress. Twenty-four men (31 ± 5 years, 26 ± 3 kg/m2) completed two study visits (control, bosentan). On each visit, BP was assessed under three conditions: (1) normoxia (FiO2 0.21), (2) chemoreflex excitation via hypoxia (FiO2 0.05-0.21), (3) chemoreflex inhibition via hyperoxia (FiO2 1.00). Bosentan increased plasma ET-1 (0.94 ± 0.90 to 1.27 ± 0.62 pg/mL, p = 0.004), supporting receptor blockade. Resting diastolic (73 ± 5 to 69 ± 7 mmHg, p = 0.007) and mean (93 ± 7 to 88 ± 7 mmHg, p = 0.005) BP were reduced following bosentan compared to control with no change in systolic BP (p = 0.507). The mean BP response to both acute hypoxia (-0.48 ± 0.38 to -0.25 ± 0.31 mmHg/%, p = 0.004) and hyperoxia (area under the curve -93 ± 108 to -27 ± 66 AU, p = 0.018) were attenuated following bosentan. Acute ET receptor inhibition attenuates the rise in BP during chemoreflex excitation as well as the fall in BP during chemoreflex inhibition in healthy young men. These data support a role for ET-1 in control of resting BP, possibly through a chemoreceptor-mediated mechanism.

Association between Plasma Big Endothelin-1 Level and The Severity of Coronary Artery Disease in Patients with Non-ST Segment-Elevated Myocardial Infarction

BACKGROUND

Early risk stratification with simple biomarkers is essential in patients with non-ST segment-elevation myocardial infarction (NSTEMI).

OBJECTIVE

This study aimed to evaluate the association between plasma big endothelin-1 (ET-1) level and the SYNTAX score (SS) in patients with NSTEMI.

METHODS

A total of 766 patients with NSTEMI undergoing coronary angiography were recruited. Patients were divided into three groups: low SS (≤22), intermediate SS (23-32), and high SS (>32). Spearman correlation, smooth curve fitting, logistic regression, and receiver operating characteristic (ROC) curve analysis were performed to evaluate the association between plasma big ET-1 level and the SS. A p-value <0.05 was considered statistically significant.

RESULTS

There was a significant correlation between the big ET-1 and the SS (r=0.378, p<0.001). The smoothing curve indicated a positive correlation between the plasma big ET-1 level and the SS. The ROC curve analysis showed that the area under the curve was 0.695 (0.661-0.727) and the optimal cutoff of plasma big ET-1 level was 0.35pmol/l. Logistic regression showed that elevated big ET-1 was an independent predictor of intermediate-high SS in patients with NSTEMI, whether entered as a continuous variable [OR (95% CI): 1.110 (1.053-1.170), p<0.001] or as a categorical variable [OR (95% CI): 2.962 (2.073-4.233), p<0.001].

CONCLUSION

In patients with NSTEMI, the plasma big ET-1 level was significantly correlated with the SS. Elevated plasma big ET-1 level was an independent predictor for intermediate-high SS.

Decompression Mechanism of Radish Seed in Prehypertension Rats through Integration of Transcriptomics and Metabolomics Methods

Radish seed (RS), the dried ripe seed of Raphanus sativus L., is widely used in traditional Chinese medicine (TCM) to reduce blood pressure. However, the molecular and pharmacological mechanisms underlying its therapeutic effects are still unclear. In this study, we analyzed the effects of RS in a rat model of prehypertension and assessed the mechanistic basis by integrating transcriptomics and metabolomics. RS administration significantly reduced blood pressure in prehypertensive male Wistar rats, negatively regulated endothelin-1, increased nitric oxide levels, and reduced the exfoliation of endothelium cells. In vitro vascular ring experiments further confirmed the effects of RS on vascular endothelial cells. Furthermore, we identified 65 differentially expressed genes (DEGs; P _adj < 0.05 and fold change (FC) > 2) and 52 metabolites (VIP > 1, P < 0.05 and FC ≥ 2 or ≤0.5) in the RS intervention group using RNA-seq and UPLC-MS/MS, respectively. A network of the DEGs and the metabolites was constructed,q which indicated that RS regulates purine metabolism, linoleic acid metabolism, arachidonic acid metabolism, circadian rhythm, and phosphatidylinositol signaling pathway, and its target genes are Pik3c2a, Hspa8, Dnaja1, Arntl, Ugt1a1, Dbp, Rasd1, and Aldh1a3. Thus, the antihypertensive effects of RS can be attributed to its ability to improve vascular endothelial dysfunction by targeting multiple genes and pathways. Our findings provide new insights into the pathological mechanisms underlying prehypertension, along with novel targets for the prevention and treatment of hypertension.

Plasma Big Endothelin-1 Levels and Long-Term Outcomes in Patients With Atrial Fibrillation and Acute Coronary Syndrome or Undergoing Percutaneous Coronary Intervention

Background

This study aimed to evaluate the association between plasma big ET-1 levels and long-term outcomes in patients with atrial fibrillation (AF) and acute coronary syndrome (ACS) or undergoing percutaneous coronary intervention (PCI).

Methods

A total of 930 patients were enrolled and followed up for a median duration of 2.3 years. According to the optimal cutoff of big ET-1 for predicting all-cause death, these patients were divided into two groups. The primary endpoints were all-cause death and net adverse clinical events (NACE). The secondary endpoints included cardiovascular death, major adverse cardiovascular events (MACE), BARC class ≥ 3 bleeding, and BARC class ≥ 2 bleeding. Cox regressions were performed to evaluate the association between big ET-1 and outcomes.

Results

Based on the optimal cutoff of 0.54 pmol/l, 309 patients (33.2%) had high big ET-1 levels at baseline. Compared to the low big ET-1 group, patients in the high big ET-1 group tended to have more comorbidities, impaired cardiac function, elevated inflammatory levels, and worse prognosis. Univariable and multivariable Cox regressions indicated that big ET-1 ≥ 0.54 pmol/l was associated with increased incidences of all-cause death [HR (95%CI):1.73 (1.10–2.71), p = 0.018], NACE [HR (95%CI):1.63 (1.23–2.16), p = 0.001], cardiovascular death [HR (95%CI):1.72 (1.01–2.92), p = 0.046], MACE [HR (95%CI):1.60 (1.19–2.16), p = 0.002], BARC class ≥ 3 [HR (95%CI):2.21 (1.16–4.22), p = 0.016], and BARC class ≥ 2 bleeding [HR (95%CI):1.91 (1.36–2.70), p < 0.001]. Subgroup analysis indicated consistent relationships between the big ET-1 ≥ 0.54 pmol/l and the primary endpoints.

Conclusion

Elevated plasma big ET-1 levels were independently associated with increased risk of all-cause death, NACE, cardiovascular death, MACE, BARC class ≥ 3 bleeding, and BARC class ≥ 2 bleeding in patients with AF and ACS or undergoing PCI.

Role of Endothelin-1 Receptors in Limiting Leg Blood Flow and Glucose Uptake During Hyperinsulinemia in Type 2 Diabetes

Skeletal muscle insulin resistance is a hallmark of individuals with type 2 diabetes mellitus (T2D). In healthy individuals insulin stimulates vasodilation, which is markedly blunted in T2D; however, the mechanism(s) remain incompletely understood. Investigations in rodents indicate augmented endothelin-1 (ET-1) action as a major contributor. Human studies have been limited to young obese participants and focused exclusively on the ET-1 A (ETA) receptor. Herein, we have hypothesized that ETA receptor antagonism would improve insulin-stimulated vasodilation and glucose uptake in T2D, with further improvements observed during concurrent ETA + ET-1 B (ETB) antagonism. Arterial pressure (arterial line), leg blood flow (LBF; Doppler), and leg glucose uptake (LGU) were measured at rest, during hyperinsulinemia alone, and hyperinsulinemia with (1) femoral artery infusion of BQ-123, the selective ETA receptor antagonist (n = 10 control, n = 9 T2D) and then (2) addition of BQ-788 (selective ETB antagonist) for blockade of ETA and ETB receptors (n = 7 each). The LBF responses to hyperinsulinemia alone tended to be lower in T2D (controls: ∆161 ± 160 mL/minute; T2D: ∆58 ± 43 mL/minute, P = .08). BQ-123 during hyperinsulinemia augmented LBF to a greater extent in T2D (% change: controls: 14 ± 23%; T2D: 38 ± 21%, P = .029). LGU following BQ-123 increased similarly between groups (P = .85). Concurrent ETA + ETB antagonism did not further increase LBF or LGU in either group. Collectively, these findings suggest that during hyperinsulinemia ETA receptor activation restrains vasodilation more in T2D than controls while limiting glucose uptake similarly in both groups, with no further effect of ETB receptors (NCT04907838).

Contributions of endothelin-1 and l-arginine to blunted cutaneous microvascular function in young, black women

Non-Hispanic black (BL) individuals have the greatest prevalence of cardiovascular disease (CVD), relative to other racial/ethnic groups (e.g., non-Hispanic white population; WH), which may be secondary to blunted vascular function. Although women typically present with reduced CVD relative to men of the same racial/ethnic group, the prevalence is similar between BL women and men though the mechanisms differ. This study hypothesized that reduced microvascular function in young, BL women is associated with endothelin-1 (ET-1) overactivity or insufficient l-arginine bioavailability. Nine BL and nine WH women participated (age: 20 ± 2 vs. 22 ± 2 yr). Cutaneous microvascular function was assessed during 39°C local heating, whereas lactated Ringer's (control), BQ-123 (ET-1 receptor type A antagonist), BQ-788 (ET-1 receptor type B antagonist), or l-arginine were infused via intradermal microdialysis to modify cutaneous vascular conductance (CVC). Subsequent infusion of N^ω-nitro-l-arginine methyl ester allowed for quantification of the nitric oxide (NO) contribution to vasodilation, whereas combined sodium nitroprusside and 43°C heating allowed for normalization to maximal CVC (%CVC_max). BL women had blunted %CVC_max and NO contribution to dilation during the 39°C plateau (P < 0.027 for both). BQ-123 improved this response through augmented NO-mediated dilation (P < 0.048 for both). BQ-788 and l-arginine did not alter the CVC responses (P > 0.835 for both) or the NO contribution (P > 0.371 for both). Cutaneous microvascular function is reduced in BL women, and ET-1 receptor type A may contribute to this reduced function. Further research is needed to better characterize these mechanisms in young, BL women.NEW & NOTEWORTHY Cardiovascular disease remains a burden in the United States non-Hispanic black (BL) population, although its manifestation through blunted vasodilation in this population is different between men and women. Accordingly, this study determined that reduced microvascular function in young, BL women may be partially controlled by endothelin-1 (ET-1) type A receptors, although neither type B receptors nor insufficient l-arginine bioavailability seems to contribute to this response. Accordingly, further research is needed to better characterize these ET-1 related mechanisms and illuminate other pathways that may contribute to this disparate vascular function in young, BL women.

Cutaneous sensory nerve-mediated microvascular vasodilation in normotensive and prehypertensive non-Hispanic Blacks and Whites

Relative to non-Hispanic Whites, non-Hispanic Blacks are disproportionately affected by elevated blood pressure (BP). It is unknown whether race or subclinical increases in BP affect the ability of cutaneous sensory nerves to induce cutaneous microvascular vasodilation. Sixteen participants who self-identified as non-Hispanic Black (n = 8) or non-Hispanic White (n = 8) were subgrouped as normotensive or prehypertensive. Participants were instrumented with three intradermal microdialysis fibers: (a) control, (b) 1 μM sodium nitroprusside (SNP), an exogenous nitric oxide (NO) donor, and (c) 20 mM NG -nitro-l-arginine methyl ester (L-NAME), a non-selective NO synthase inhibitor. A slow local heating protocol (33-40°C, 0.1°C/min) was used to assess the onset of cutaneous sensory nerve-mediated vasodilation (temperature threshold) and skin blood flow was measured using laser-Doppler flowmetry. At control sites, the temperature threshold occurred at a higher temperature in non-Hispanic Blacks (normotensive: 37.2 ± 0.6°C, prehypertensive: 38.9 ± 0.5°C) compared to non-Hispanic Whites (normotensive: 35.2 ± 0.8°C, prehypertensive: 35.2 ± 0.9°C). L-NAME shifted the temperature threshold higher in non-Hispanic Whites (normotensive: 37.8 ± 0.7°C, prehypertensive: 38.2 ± 0.8°C), but there was no observed effect in non-Hispanic Blacks. SNP did not affect temperature threshold in non-Hispanic Whites, but shifted the temperature threshold lower in non-Hispanic Blacks (normotensive: 34.6 ± 1.2°C, prehypertensive: 34.8 ± 1.1°C). SNP mitigated differences in temperature threshold across all groups. There was no effect found for BP status in either the non-Hispanic Black or non-Hispanic White groups. These data suggest that reduced NO bioavailability affects the ability of cutaneous sensory nerves to induce microvascular vasodilation in young, otherwise healthy non-Hispanic Blacks.

Chronic Elevation of Endothelin-1 Alone May Not Be Sufficient to Impair Endothelium-Dependent Relaxation

Endothelin-1 (ET-1) is a powerful vasoconstrictor peptide considered to be causally implicated in hypertension and the development of cardiovascular disease. Increased ET-1 is commonly associated with reduced NO bioavailability and impaired vascular function; however, whether chronic elevation of ET-1 directly impairs endothelium-dependent relaxation (EDR) remains elusive. Herein, we report that (1) prolonged ET-1 exposure (ie, 48 hours) of naive mouse aortas or cultured endothelial cells did not impair EDR or reduce eNOS (endothelial NO synthase) activity, respectively (P>0.05); (2) mice with endothelial cell-specific ET-1 overexpression did not exhibit impaired EDR or reduced eNOS activity (P>0.05); (3) chronic (8 weeks) pharmacological blockade of ET-1 receptors in obese/hyperlipidemic mice did not improve aortic EDR or increase eNOS activity (P>0.05); and (4) vascular and plasma ET-1 did not inversely correlate with EDR in resistance arteries isolated from human subjects with a wide range of ET-1 levels (r=0.0037 and r=-0.1258, respectively). Furthermore, we report that prolonged ET-1 exposure downregulated vascular UCP-1 (uncoupling protein-1; P<0.05), which may contribute to the preservation of EDR in conditions characterized by hyperendothelinemia. Collectively, our findings demonstrate that chronic elevation of ET-1 alone may not be sufficient to impair EDR.

A Novel Antithrombotic Protease from Marine Worm Sipunculus Nudus

Sipunculus nudus, an old marine species, has great potential for use as functional seafood due to its various bioactivities. Its potential antithrombotic activity pushed us to isolate the bio-active components bio-guided by tracking fibrinolytic activity. As a result, a novel protease named as SK (the kinase obtained from S. nudus) was obtained, which possessed a molecular weight of 28,003.67 Da and 15 N-terminal amino acid sequences of PFPVPDPFVWDTSFQ. SK exerted inhibitory effects on thrombus formation through improving the coagulation system with dose-effect relationship within a certain range. Furthermore, in most cases SK got obviously better effect than that of urokinase. With the help of untargeted mass spectrometry-based metabolomics profiling, arachidonic acid, sphingolipid, and nicotinate and nicotinamide mechanism pathways were found to be important pathways. They revealed that the effect mechanism of SK on common carotid arterial thrombosis induced by FeCl₃ was achieved by inhibiting vessel contraction, platelet aggregation, adhesion, and release, correcting endothelial cell dysfunction and retarding process of thrombus formation. This study demonstrated SK was a promising thrombolytic agent on the basis of its comprehensive activities on thrombosis, and it should get further exploitation and utilization.

Autonomic and Vascular Control in Prehypertensive Subjects with a Family History of Arterial Hypertension

BACKGROUND

Individuals with a family history of systemic arterial hypertension (FHSAH) and / or prehypertension have a higher risk of developing this pathology.

OBJECTIVE

To evaluate the autonomic and vascular functions of prehypertensive patients with FHSAH.

METHODS

Twenty-five young volunteers with FHSAH, 14 normotensive and 11 prehypertensive subjects were submitted to vascular function evaluation by forearm vascular conductance(VC) during resting and reactive hyperemia (Hokanson®) and cardiac and peripheral autonomic modulation, quantified, respectively, by spectral analysis of heart rate (ECG) and systolic blood pressure (SBP) (FinometerPRO®). The transfer function analysis was used to measure the gain and response time of baroreflex. The statistical significance adopted was p ≤ 0.05.

RESULTS

Pre-hypertensive individuals, in relation to normotensive individuals, have higher VC both at rest (3.48 ± 1.26 vs. 2.67 ± 0.72 units, p = 0.05) and peak reactive hyperemia (25, 02 ± 8.18 vs. 18.66 ± 6.07 units, p = 0.04). The indices of cardiac autonomic modulation were similar between the groups. However, in the peripheral autonomic modulation, greater variability was observed in prehypertensive patients compared to normotensive individuals (9.4 [4.9-12.7] vs. 18.3 [14.8-26.7] mmHg2; p < 0.01) and higher spectral components of very low (6.9 [2.0-11.1] vs. 13.5 [10.7-22.4] mmHg2, p = 0.01) and low frequencies (1.7 [1.0-3.0] vs. 3.0 [2.0-4.0] mmHg2, p = 0.04) of SBP. Additionally, we observed a lower gain of baroreflex control in prehypertensive patients compared to normotensive patients (12.16 ± 4.18 vs. 18.23 ± 7.11 ms/mmHg, p = 0.03), but similar delay time (-1.55 ± 0.66 vs. -1.58 ± 0.72 s, p = 0.90).

CONCLUSION

Prehypertensive patients with FHSAH have autonomic dysfunction and increased vascular conductance when compared to normotensive patients with the same risk factor.

Low Plasma Testosterone Is Associated With Elevated Cardiovascular Disease Biomarkers

BACKGROUND

The relation between testosterone (T) plasma concentration and cardiovascular (CV) risk is unclear, with evidence supporting increased risk in men with low and high T levels. Few studies have assessed CV risk as a function of plasma T levels using objective biomarkers.

AIM

To determine the relation between T levels and high-sensitivity CV risk biomarkers.

METHODS

Ten thousand forty-one male patients were identified in the database of a commercial clinical laboratory performing biomarker testing. Patients were grouped by total T concentration and associations with the following biomarkers were determined: cardiac troponin I (cTnI), endothelin-1 (ET-1), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interleukin-17A, N-terminal pro-B-type natriuretic peptide (NTproBNP), high-density lipoprotein (HDL) cholesterol, high-sensitivity C-reactive protein (hs-CRP), hemoglobin A_1c (HbA_1c), and leptin.

OUTCOMES

Association of CV risk markers with levels of T in men.

RESULTS

The median age of the cohort was 58 years (interquartile range = 48-68), and the median plasma T level was 420 ng/dL (interquartile range = 304-565); T levels did not vary with patient age. An inverse relation between plasma T levels and CV risk was observed for 9 of 10 CV markers: cTnI, ET-1, IL-6, TNF-α, NTproBNP, HDL cholesterol, hs-CRP, HbA_1c, and leptin. Even after adjusting for age, body mass index, HbA_1c, hs-CRP, and HDL cholesterol levels, the CV markers IL-6, ET-1, NTproBNP, and leptin were significantly associated with a T level lower than 250 ng/dL.

CLINICAL IMPLICATIONS

Men with low T levels could be at increased risk for increased CV disease as seen by increased CV risk markers.

STRENGTH AND LIMITATIONS

This study was performed in a group of 10,041 men and is the first study to examine CV risk associated with circulating T levels using a large panel of 10 objective biomarkers. This study is limited by an absence of clinical data indicating whether men had pre-existing CV disease or other CV risk factors.

CONCLUSION

Men with low plasma T levels exhibit increases in CV risk markers, consistent with a potential increased risk of CV disease. Pastuszak AW, Kohn TP, Estis J, Lipshultz LI. Low Plasma Testosterone Is Associated With Elevated Cardiovascular Disease Biomarkers. J Sex Med 2017;14:1095-1103.

Endothelial vasodilator function in normal-weight adults with metabolic syndrome

Metabolic syndrome (MetS) typically presents with obesity; however, obesity is not a requisite characteristic for MetS classification and related vascular risk. We tested the hypothesis that MetS, independent of excess adiposity, is associated with impaired endothelial vasodilator dysfunction. Thirty-two sedentary, middle-aged adults were studied: 11 normal weight (9 male and 2 female; body mass index (BMI), 24.0 ± 0.3 kg/m2); 11 normal weight with MetS (9 male and 2 female; BMI, 24.7 ± 0.3 kg/m2); and 10 obese without MetS (8 male and 2 female; BMI, 31.4 ± 0.5 kg/m2). MetS was established according to National Cholesterol Education Program Adult Treatment Panel III criteria. Forearm blood flow (FBF) responses to intra-arterial infusions of acetylcholine and sodium nitroprusside were measured via strain-gauge plethysmography. FBF responses to acetylcholine were ∼20% lower (P < 0.05) in the normal-weight subjects with MetS (from 4.0 ± 0.3 to 13.0 ± 1.0 mL/(100 mL tissue·min)) and obese subjects (from 4.8 ± 0.2 to 12.2 ± 1.1 mL/(100 mL tissue·min)) compared with the normal-weight subjects (from 4.6 ± 0.4 to 15.8 ± 0.7 mL/(100 mL tissue·min)). Of note, FBF responses to acetylcholine were similar between the normal-weight adults with MetS and the obese adults. There were no differences among groups in FBF response to sodium nitroprusside. These data indicate that the presence of MetS, independent of obesity, is associated with diminished endothelium-dependent vasodilation. Endothelial vasodilator dysfunction may underlie the increased cardiovascular risk in normal-weight adults with MetS.

Skeletal Muscle Vascular Function: A Counterbalance of Insulin Action

Insulin is a vasoactive hormone that regulates vascular homeostasis by maintaining balance of endothelial-derived NO and ET-1. Although there is general agreement that insulin resistance and the associated hyperinsulinemia disturb this balance, the vascular consequences for hyperinsulinemia in isolation from insulin resistance are still unclear. Presently, there is no simple answer for this question, especially in a background of mixed reports examining the effects of experimental hyperinsulinemia on endothelial-mediated vasodilation. Understanding the mechanisms by which hyperinsulinemia induces vascular dysfunction is essential in advancing treatment and prevention of insulin resistance-related vascular complications. Thus, we review literature addressing the effects of hyperinsulinemia on vascular function. Furthermore, we give special attention to the vasoregulatory effects of hyperinsulinemia on skeletal muscle, the largest insulin-dependent organ in the body. This review also characterizes the differential vascular effects of hyperinsulinemia on large conduit vessels versus small resistance microvessels and the effects of metabolic variables in an effort to unravel potential sources of discrepancies in the literature. At the cellular level, we provide an overview of insulin signaling events governing vascular tone. Finally, we hypothesize a role for hyperinsulinemia and insulin resistance in the development of CVD.

Chronic Nebivolol Treatment Suppresses Endothelin-1-Mediated Vasoconstrictor Tone in Adults With Elevated Blood Pressure

Endothelin-1 (ET-1) plays a major role in the pathophysiology of hypertension and its associated cardiovascular risk. We tested the hypothesis that chronic nebivolol treatment reduces ET-1-mediated vasoconstrictor tone in adult humans with elevated blood pressure (BP). Furthermore, reducing ET-1 vasoconstrictor activity contributes to the improvement in endothelial vasodilator function associated with nebivolol treatment. Forty-two middle-aged adults with elevated BP (systolic BP ≥130 mm Hg or diastolic BP ≥85 mm Hg) completed a 3-month, double-blind, randomized, placebo controlled trial: 14 received nebivolol (8 men/6 women; 5 mg per day); 14 received metoprolol succinate (9 men/5 women; 100 mg per day); and 14 received placebo (9 men/5 women). Forearm blood flow (plethysmography) responses to selective (BQ-123: 100 nmol/min; 60 minutes) and nonselective (BQ-123+BQ-788 [50 nmol/min]; 60 minutes) ET-1 receptor blockade, as well as acetylcholine (4.0, 8.0, and 16.0 μg per 100 mL of tissue per minute) in the absence and presence of nonselective ET-1 receptor blockade were determined before and after each treatment intervention. Forearm blood flow responses to BQ-123 and BQ-123+BQ-788 were similarly and significantly elevated (≈30% and 60%, respectively) from baseline in all 3 groups. Nebivolol, but not metoprolol or placebo, therapy resulted in a marked (≈25% and 45%; P<0.05) reduction in forearm blood flow response to BQ-123 and BQ-123+BQ-788. Moreover, after nebivolol therapy only, vasodilator response to acetylcholine was not significantly increased by ET-1 receptor blockade. These results demonstrate that nebivolol, but not metoprolol, treatment reduces ET-1-mediated vasoconstrictor tone in adult humans with elevated BP. In addition, nebivolol-induced reduction in ET-1-mediated vasoconstrictor tone underlies the favorable effects of this β-blocker on endothelial vasodilation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01395329.

Abnormal phosphorylation of Tie2/Akt/eNOS signaling pathway and decreased number or function of circulating endothelial progenitor cells in prehypertensive premenopausal women with diabetes mellitus

BACKGROUNDS

The number and activity of circulating endothelial progenitor cells (EPCs) in prehypertension is preserved in premenopausal women. However, whether this favorable effect still exists in prehypertensive premenopausal women with diabetes is not clear.

METHODS

This study compared the number and functional activity of circulating EPCs in normotensive or prehypertensive premenopausal women without diabetes mellitus and normotensive or prehypertensive premenopausal women with diabetes mellitus, evaluated the vascular endothelial function in each groups, and investigated the possible underlying mechanism.

RESULTS

We found that compared with normotensive premenopausal women, the number and function of circulating EPCs, as well as endothelial function evaluated by flow-mediated dilatation (FMD) in prehypertensive premenopausal women were preserved. In parallel, the Tie2/Akt/eNOS signaling pathway and the plasma NO level or NO secretion of circulating EPCs in prehypertensive premenopausal women was also retained. However, in presence of normotension or prehypertension with diabetes mellitus, the number or function of circulating EPCs and FMD in premenopausal women decreased. Similarly, the phosphorylation of Tie2/Akt/eNOS signaling pathway and the plasma NO level or NO secretion of circulating EPCs was reduced in prehypertension premenopausal with diabetes mellitus.

CONCLUSION

The present findings firstly demonstrate that the unfavorable effects of diabetes mellitus on number and activity of circulating EPCs in prehypertension premenopausal women, which is at least partially related to the abnormal phosphorylation of Tie2/Akt/eNOS signaling pathway and subsequently reduced nitric oxide bioavailability. The Tie2/Akt/eNOS signaling pathway may be a potential target of vascular protection in prehypertensive premenopausal women with diabetes mellitus.

A Mediterranean diet supplemented with extra virgin olive oil or nuts improves endothelial markers involved in blood pressure control in hypertensive women

PURPOSE

Serum nitric oxide (NO) reduction and increased endothelin-1 (ET-1) play a pivotal role in endothelial dysfunction and hypertension. Considering that traditional Mediterranean diet (TMD) reduces blood pressure (BP), the aim of this study was to analyze whether TMD induced changes on endothelial physiology elements such as NO, ET-1 and ET-1 receptors which are involved in BP control.

METHODS

Non-smoking women with moderate hypertension were submitted for 1 year to interventions promoting adherence to the TMD, one supplemented with extra virgin olive oil (EVOO) and the other with nuts versus a control low-fat diet (30 participants/group). BP, NO, ET-1 and related gene expression as well as oxidative stress biomarkers were measured.

RESULTS

Serum NO and systolic BP (SBP) or diastolic BP (DBP) were negatively associated at baseline, as well as between NO and ET-1. Our findings also showed a DBP reduction with both interventions. A negative correlation was observed between changes in NO metabolites concentration and SBP or DBP after the intervention with TMD + EVOO (p = 0.033 and p = 0.044, respectively). SBP reduction was related to an impairment of serum ET-1 concentrations after the intervention with TMD + nuts (p = 0.008). We also observed changes in eNOS, caveolin 2 and ET-1 receptors gene expression which are related to NO metabolites levels and BP.

CONCLUSIONS

The changes in NO and ET-1 as well as ET-1 receptors gene expression explain, at least partially, the effect of EVOO or nuts on lowering BP among hypertensive women.

Increased endothelial progenitor cells and nitric oxide in young prehypertensive women

This study investigated the effect of sex differences on circulating endothelial progenitor cells (EPCs) in prehypertension and its underlying mechanism. The authors found that premenopausal women show increased number and activity of circulating EPCs when compared with men, which was similar to enhanced nitric oxide (NO) level in plasma or culture medium. There was no difference in the number and activity of circulating EPCs and NO level between normotensive and prehypertensive premenopausal women. There was also no difference seen in levels of vascular endothelial growth factor and granulocyte macrophage colony-stimulating factor. Both number and activity of circulating EPCs were correlated with the level of NO. The present study firstly demonstrated that the number and activity of circulating EPCs were preserved in prehypertensive premenopausal women, which was related to the restoration of NO production. The sex differences in EPCs in prehypertension may be involved in the mechanism underlying vascular protection in premenopausal women.

Impaired endogenous fibrinolytic capacity in prehypertensive men

Prehypertension (BP 120–139/80–89 mmHg) is associated with an increased risk for future atherothrombotic events. Although the mechanisms underlying this elevated risk are not completely understood, one possibility is that prehypertension is associated with impaired endothelial fibrinolytic capacity. We tested the hypothesis that vascular endothelial release of t-PA is impaired in prehypertensive men. Net endothelial release of t-PA was determined, in vivo, in response to intrabrachial infusions of bradykinin (12.5, 25, 50 ng/100 mL tissue/min) and sodium nitroprusside at (1.0, 2.0, 4.0 µg/100 mL tissue/min) in 42 middle-age and older men: 16 normotensive (BP range: 100–119/57–79 mmHg); 16 prehypertensive (BP range: 120–139/76–89 mmHg); and 10 hypertensive (BP range: 140–150/74–100 mmHg). Net release of t-PA antigen was ~25% lower (P < 0.05) in the prehypertensive (−0.9 ± 0.8 to 42.4 ± 5.3 ng/100 mL tissue/min) compared with the normotensive (0.5 ± 1.0 to 53.9 ± 6.5 ng/100 mL tissue/min) men. There was no significant difference in t-PA release between the hypertensive (−1.8±1.6 to 40.8±6.6 ng/100 mL tissue/min) and prehypertensive groups. Sodium nitroprusside did not significantly alter t-PA release in any group. These data indicate that endothelial t-PA release is diminished in prehypertensive men. Further, the level of impairment in t-PA release seen with clinical hypertension is already apparent in the prehypertensive state. Impaired endothelial fibrinolytic function may underlie the increased atherothrombotic risk associated with blood pressure in the prehypertensive range.

Plasma big endothelin-1 level and the severity of new-onset stable coronary artery disease

AIM

To investigate the usefulness of the plasma big endothelin-1 (big ET-1) level in predicting the severity of new-onset stable angiography-proven coronary artery disease (CAD).

METHODS

A total of 963 consecutive stable CAD patients with more than 50% stenosis in at least one main vessel were enrolled. The patients were classified into the three groups according to the tertile of the Gensini score (GS, low GS ＜20, n=300; intermediate GS 20-40, n=356 and high GS ＞40, n=307), and the relationship between the big ET-1 level and GS was evaluated.

RESULTS

The plasma levels of big ET-1 increased significantly in association with increases in the GS tertile (p=0.007). A multivariate analysis suggested that the plasma big ET-1 level was an independent predictor for a high GS (OR=2.26, 95%CI: 1.23-4.15, p=0.009), and there was a positive correlation between the big ET-1 level and the GS (r=0.20, p=0.000). The area under the receiver operating characteristic curve (AUC) for the big ET-1 level in predicting a high GS was 0.64 (95% CI 0.60-0.68, p=0.000), and the optimal cutoff value for the plasma big ET-1 level for predicting a high GS was 0.34 fmol/mL, with a sensitivity of 62.6% and specificity of 60.3%. In the high-big ET-1 level group (≥0.34 fmol/mL), there were significantly increased rates of three-vessel disease (43.6% vs. 35.4%, p=0.017) and a high GS [31 (17-54) vs. 24 (16-44), p=0.001] compared with that observed in the low-big ET-1 level group.

CONCLUSIONS

The present findings indicate that the plasma big ET-1 level is a useful predictor of the severity of new-onset stable CAD associated with significant stenosis.

Effects of ambrisentan in a patient affected by combined pulmonary fibrosis and emphysema and by severe pulmonary hypertension: clinical, functional, and biomolecular findings

Combined pulmonary fibrosis and emphysema (CPFE) is a computed tomography (CT)-defined syndrome of combined pulmonary fibrosis and emphysema, characterized by subnormal spirometry, impairment of gas exchange, and high prevalence of pulmonary hypertension. Although endothelin-1 (ET-1) plays an important role in the development of lung fibrosis as well as in pulmonary hypertension, no ET-1-targeted therapy is currently recommended. Here we report a case of CPFE successfully treated with ambrisentan, an endothelin-A receptor antagonist, and also discuss the biologic mechanisms underlying the observed therapeutic effects. A 79-year-old man with chronic obstructive pulmonary disease (COPD) was referred to our respiratory unit as an outpatient for dyspnea. Clinical, radiologic, and laboratory findings suggested a diagnosis of chronic hypoxemic, type 1 respiratory failure, due to combined pulmonary fibrosis and emphysema, complicated by severe, precapillary pulmonary hypertension. Pharmacologic treatment with ambrisentan induced an initial improvement in clinical symptoms that proved to be very relevant 9 months later. In order to investigate the biologic mechanisms underlying the clinical effects of ambrisentan, we performed an "in vitro" study on primary cultures of fibrotic human lung fibroblasts, as well as on human umbilical vein endothelial cells, incubated for 24 and 48 h with ET-1, in the absence or presence of an overnight treatment with ambrisentan. ET-1 significantly increased cell proliferation and mitogen-activated protein kinase activation (P < 0.01). These effects were significantly (P < 0.01) inhibited by ambrisentan in both cell cultures. In conclusion, we hypothesize that the clinical benefits induced by ambrisentan in this patient with CPFE can be attributed to its vasodilator and anti-proliferative actions, exerted on pulmonary the vascular bed and lung fibroblasts.