Endothelial Dysfunction: The Common Consequence in Diabetes and Hypertension:

Exploring the potential effect of electroacupuncture on cardiovascular function and lipid profiles in spontaneously hypertensive rats

Background

Investigating the effects of electroacupuncture (EA) treatment on cardiovascular function and aortic lipid profiles in spontaneously hypertensive rats (SHR) constitutes the foundational focus of this study. The overarching goal is to comprehensively elucidate the alterations brought about by EA treatment and to assess its potential as an alternative therapy for hypertension.

Methods

Consecutive EA treatments were administered to SHR, and the effects on systolic blood pressure, cardiac function, and hypertension-related neuronal signals were assessed. Aortic lipid profiles in vehicle-treated SHR and EA-treated SHR groups were analyzed using mass spectrometry-based lipid profiling. Additionally, the expression of Cers2 and GNPAT, enzymes involved in the synthesis of specific aortic lipids, was examined.

Results

The study demonstrated that consecutive EA treatments restored systolic blood pressure, improved cardiovascular function, and normalized hypertension-related neuronal signals in SHR. Analysis of the aortic lipid profiles revealed distinct differences between the vehicle-treated SHR group and the EA-treated SHR group. Specifically, EA treatment significantly altered the levels of aortic sphingomyelin and phospholipids, including very long-chain fatty acyl-ceramides and ether phosphatidylcholines. These changes in aortic lipid profiles correlated significantly with systolic blood pressure and cardiac function indicators. Furthermore, EA treatment significantly altered the expression of Cers2 and GNPAT.

Conclusions

The findings suggest that EA may influence cardiovascular functions and aortic lipid profiles in SHR.

Extracellular vesicles and endothelial dysfunction in infectious diseases

Cardiovascular diseases (CVDs) remain the leading cause of mortality and morbidity globally. Studies have shown that infections especially bacteraemia and sepsis are associated with increased risks for endothelial dysfunction and related CVDs including atherosclerosis. Extracellular vesicles (EVs) are small, sealed membrane-derived structures that are released into body fluids and blood from cells and/or microbes and are critically involved in a variety of important cell functions and disease development, including intercellular communications, immune responses and inflammation. It is known that EVs-mediated mechanism(s) is important in the development of endothelial dysfunction in infections with a diverse spectrum of microorganisms including Escherichia coli, Candida albicans, SARS-CoV-2 (the virus for COVID-19) and Helicobacter pylori. H. pylori infection is one of the most common infections globally. During H. pylori infection, EVs can carry H. pylori components, such as lipopolysaccharide, cytotoxin-associated gene A, or vacuolating cytotoxin A, and transfer these substances into endothelial cells, triggering inflammatory responses and endothelial dysfunction. This review is to illustrate the important role of EVs in the pathogenesis of infectious diseases, and the development of endothelial dysfunction in infectious diseases especially H. pylori infection, and to discuss the potential mechanisms and clinical implications.

'Oxidative stress'-A new target in the management of diabetes mellitus

Diabetes mellitus (DM) is a chronic condition that poses a mammoth challenge for the healthcare system in developing as well as developed nations. Diabetes mellitus is associated with damage to the vasculature which leads to microvascular and macrovascular complications. Oxidative stress is a consequence of glucotoxicity and lipotoxicity, which are associated with diabetes. Glucotoxicity and lipotoxicity play a part in the pathogenesis of β-cell dysfunction. The hyperglycemic state in DM leads to oxidative stress which further hampers insulin secretion. In diabetes, the biological antioxidants also get depleted along with a reduction in glutathione (GSH), an increase in the oxidized glutathione (GSSG)/GSH ratio, and a depletion of non-enzymatic antioxidants. This results in the formation of a viscous circle of hyperglycemia leading to increased oxidative stress that further hampers insulin secretion which in turn results in hyperglycemia. Antioxidants are efficacious in reducing diabetic complications. The antioxidants produced biologically fall short, hence external supplements are required. In this review, the authors have discussed the relationship between oxidative stress in DM and the advantages of antioxidant supplements in controlling blood glucose levels and also in deaccelerating the complications related to DM.

Venous endothelial function in cardiovascular disease

The essential role of the endothelium in vascular homeostasis is associated with the release of endothelium-dependent relaxing and contractile factors (EDRF and EDCF, respectively). Different from arteries, where these factors are widely studied, the vasoactive factors derived from the venous endothelium have been given less attention. There is evidence for a role of the nitric oxide (NO), endothelium-dependent hyperpolarization (EDH) mechanism, and cyclooxygenase (COX)-derived metabolites as EDRFs; while the EDCFs need to be better evaluated since no consensus has been reached about their identity in venous vessels. The imbalance between the synthesis, bioavailability, and/or action of EDRFs and/or EDCFs results in a pathological process known as endothelial dysfunction, which leads to reduced vasodilation and/or increased vasoconstriction. In the venous system, endothelial dysfunction is relevant since reduced venodilation may increase venous tone and decrease venous compliance, thus enhancing mean circulatory filling pressure, which maintains or modify cardiac workload contributing to the etiology of cardiovascular diseases. Interestingly, some alterations in venous function appear at the early stages (or even before) the establishment of these diseases. However, if the venous endothelium dysfunction is involved in these alterations is not yet fully understood and requires further studies. In this sense, the present study aims to review the current knowledge on venous endothelial function and dysfunction, and the general state of the venous tone in two important cardiovascular diseases of high incidence and morbimortality worldwide: hypertension and heart failure.

Rosa damascena Miller essential oil relaxes rat thoracic aorta through the NO-cGMP-dependent pathway

AIM

This study aimed to investigate the effects of Rosa damascena Mill. essential oil on the vascular activity of rat thoracic aorta and its underlying mechanisms.

METHODS

Experiments were performed using the isolated tissue bath model and Wistar rats. 0.1, 1, 10, and 100 µg/mL concentrations of rose oil were administered in all groups. To determine the vasoactive effects of rose oil, submaximal contractions were conducted by applying 10^-5 M PE and 45 mM KCl separately in both endothelium-intact and -denuded segments. Time-matched distilled water groups were formed for control. To evaluate the role of endothelium-derived vasodilative factors, endothelium-intact segments were incubated with nitric oxide synthase inhibitor L-NAME, soluble guanylate cyclase inhibitor ODQ, and a non-selective cyclooxygenase inhibitor INDO. The statistical significance level was considered as p < 0.05.

RESULTS

1, 10, and 100 µg/mL rose oil doses led to vasorelaxation in thoracic aortas precontracted with 10^-5 M PE (p: 0.029, p: 0.000, p: 0.000, respectively). In precontracted thoracic aortas with 45 mM KCl, the significant effect of rose oil persisted, albeit slightly diminished. When the endothelium was removed, the relaxant effect of rose oil was partially reduced, but still significant (p: 0.035, p: 0.028, p: 0.000, respectively). Preincubations with L-NAME and ODQ significantly attenuated rose oil-induced relaxation of endothelium-intact aortas precontracted with 10^-5 M PE. In contrast, preincubation INDO did not modulate rose oil-induced relaxation.

CONCLUSION

In conclusion, it was shown for the first time that rose oil can significantly mediate vasorelaxation in both PE and KCl precontracted rat thoracic aortas. Rose oil induced vasodilation with or without endothelium in a concentration-dependent manner. It was also shown that rose oil-induced vasorelaxant effects were reduced by L-NAME or ODQ pretreatment, but not modulated by INDO. These results demonstrated that rose oil-induced endothelium-dependent vasodilation is mediated by the NO-cGMP-dependent pathway.

Geraniol and β-citronellol participate in the vasorelaxant effects of Rosa damascena Miller essential oil on the rat thoracic aorta

AIM

This study aimed to investigate the vasoactive effects of Rosa damascena Miller essential oil and its major components, geraniol and β-citronellol, on the rat thoracic aorta.

METHODS

Isolated tissue bath model and Wistar rats were used to perform the experiments. Two-fold increasing concentrations (20-160 μg/mL) of rose oil were administered to determine its vasoactive effects. Submaximal contractions were induced by PE or KCl in both endothelium-intact and -denuded segments. Time-matched control groups were also formed. To evaluate the role of geraniol and β-citronellol, concentrations in the range of 0.4-3.2 μg/mL and 0.8-6.4 μg/mL were applied respectively. The statistical significance level was considered as p < 0.05.

RESULTS

All doses of rose oil applied led to vasorelaxation in thoracic aortas precontracted with PE. In precontracted thoracic aortas with KCl, the significant effect of rose oil persisted, albeit slightly diminished. When the endothelium was removed, the relaxant effect of rose oil was partially reduced, but still significant. Besides, although geraniol relaxed aortic segments at all concentrations (0.4 to 3.2 μg/mL), β-citronellol caused vasorelaxation at doses of 1.6, 3.2, and 6.4 μg/mL.

CONCLUSION

In conclusion, the first findings were obtained that rose oil can cause a vasorelaxant effect in a concentration-dependent manner in rat thoracic aorta. This effect substantially persisted in vascular segments without endothelium or precontracted with KCl. It was further shown for the first time that geraniol and β-citronellol exert vasodilatory effects on the rat thoracic aorta. These results suggest that rose oil exhibits its vasorelaxant effect through geraniol and β-citronellol.

Antioxidant Potential of Adiponectin and Full PPAR-γ Agonist in Correcting Streptozotocin-Induced Vascular Abnormality in Spontaneously Hypertensive Rats

Oxidative stress, which is associated with metabolic and anthropometric perturbations, leads to reactive oxygen species production and decrease in plasma adiponectin concentration. We investigated pharmacodynamically the pathophysiological role and potential implication of exogenously administered adiponectin with full and partial peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonists on modulation of oxidative stress, metabolic dysregulation, and antioxidant potential in streptozotocin-induced spontaneously hypertensive rats (SHR). Group I (WKY) serves as the normotensive control, whereas 42 male SHRs were randomized equally into 7 groups (n = 6); group II serves as the SHR control, group III serves as the SHR diabetic control, and groups IV, V, and VI are treated with irbesartan (30 mg/kg), pioglitazone (10 mg/kg), and adiponectin (2.5 μg/kg), whereas groups VII and VIII received cotreatments as irbesartan+adiponectin and pioglitazone+adiponectin, respectively. Diabetes was induced using an intraperitoneal injection of streptozotocin (40 mg/kg). Plasma adiponectin, lipid contents, and arterial stiffness with oxidative stress biomarkers were measured using an in vitro and in vivo analysis. Diabetic SHRs exhibited hyperglycemia, hypertriglyceridemia, hypercholesterolemia, and increased arterial stiffness with reduced plasma adiponectin and antioxidant enzymatic levels (P < 0.05). Diabetic SHRs pretreated with pioglitazone and adiponectin separately exerted improvements in antioxidant enzyme activities, abrogated arterial stiffness, and offset the increased production of reactive oxygen species and dyslipidemic effects of STZ, whereas the blood pressure values were significantly reduced in the irbesartan-treated groups (all P < 0.05). The combined treatment of exogenously administered adiponectin with full PPAR-γ agonist augmented the improvement in lipid contents and adiponectin concentration and restored arterial stiffness with antioxidant potential effects, indicating the degree of synergism between adiponectin and full PPAR-γ agonists (pioglitazone).

Peroxisome proliferator-activated receptor agonist (pioglitazone) with exogenous adiponectin ameliorates arterial stiffness and oxidative stress in diabetic Wistar Kyoto rats

Oxidative stress causes hypoadiponectemia and reactive oxygen species production. This study investigates the pathophysiological role and potential effects of adiponectin with partial and full peroxisome proliferator-activated receptor-gamma agonists on modulation of metabolic dysregulation and oxidative stress in diabetic model of Wistar Kyoto rats (WKY). Forty two male WKY rats were randomized equally into 7 groups (n = 6), Group I serve as control, group II as WKY diabetic control, groups III, IV and V treated with irbesartan (30 mg/kg), pioglitazone (10 mg/kg) and adiponectin (2.5 μg/kg), groups VI and VII were co-treated as: irbesartan + adiponectin, pioglitazone + adiponectin, respectively. Streptozotocin @ 40 mg/kg was administered intraperitoneally to induce diabetes. Plasma adiponectin, metabolic indices, pulse wave velocity, oxidative stress and antioxidant enzymatic activities were measured. Streptozotocin induced WKYs expressed hyperglycaemia, hypertriglyceridemia, hypercholesterolemia, hypoadiponectemia, increased arterial stiffness and decreased antioxidant enzymatic levels (P<0.05). Treatment with adiponectin or pioglitazone alone showed improvements in metabolic indices, antioxidant enzymes, and abrogated arterial stiffness, attenuated generation of reactive oxygen species and dyslipidaemic effects of streptozotocin better as compared to irbesartan sets of treatment (all P<0.05). Co-treatment of adiponectin with pioglitazone significantly amplified the improvement in plasma triglycerides, adiponectin concentration, pulse wave velocity and antioxidant enzymatic activities indicating synergistic effects of adiponectin with full PPAR-γ agonist.

Vascular damage effect of circulating microparticles in patients with ACS is aggravated by type 2 diabetes

As a common factor of both type 2 diabetes mellitus (T2DM) and acute coronary syndrome (ACS), circulating microparticles (MPs) may provide a link between these two diseases. The present study compared the content and function of MPs from patients with ACS with or without T2DM. MPs from healthy subjects (n=20), patients with ACS (n=24), patients with T2DM (n=20) and patients with combined ACS and T2DM (n=24) were obtained. After incubating rat thoracic tissue with MPs, the effect of MPs on endothelial‑dependent vasodilatation, expression of caveolin‑1 and endothelial nitric oxide synthase (eNOS), phosphorylation of eNOS at the S1177 and T495 sites and its association with heat shock protein 90 (Hsp90), and the generation of NO and superoxide anion (O_2˙‑) were determined. MP concentrations were higher in patients with T2DM and patients with ACS with or without T2DM than in healthy subjects. Moreover, MPs from patients with T2DM or ACS led to impairment in endothelial‑dependent vasodilatation, decreased expression of NO, as well as eNOS and its phosphorylation at Ser1177 and association with Hsp90, but increased eNOS phosphorylation at T495, caveolin‑1 expression and O_2˙‑ generation. These effects were strengthened by MPs from patients with ACS combined with T2DM. T2DM not only increased MP content but also resulted in greater vascular impairment effects in ACS. These results may provide novel insight into the treatment of patients with ACS and T2DM.

Exosomal MicroRNAs Contribute to Cognitive Impairment in Hypertensive Patients by Decreasing Frontal Cerebrovascular Reactivity

Mechanisms underlying cognitive impairment (CI) in hypertensive patients remain relatively unclear. The present study aimed to explore the relationship among serum exosomal microRNAs (miRNAs), cerebrovascular reactivity (CVR), and cognitive function in hypertensive patients. Seventy-three hypertensive patients with CI (HT-CI), 67 hypertensive patients with normal cognition (HT-NC), and 37 healthy controls underwent identification of exosomal miRNA, multimodal magnetic resonance imaging (MRI) scans, and neuropsychological tests. CVR mapping was investigated based on resting-state functional MRI data. Compared with healthy subjects and HT-NC subjects, HT-CI subjects displayed decreased serum exosomal miRNA-330-3p. The group difference of CVR was mainly found in the left frontal lobe and demonstrated that HT-CI group had a lower CVR than both HT-NC group and control group. Furthermore, both the CVR in the left medial superior frontal gyrus and the miRNA-330-3p level were significantly correlated with executive function (r = -0.275, P = 0.021, and r = -0.246, P = 0.04, respectively) in HT-CI subjects, and the CVR was significantly correlated with the miRNA-330-3p level (r = 0.246, P = 0.040). Notably, path analysis showed that the CVR mediated the association between miRNA-330-3p and executive function. In conclusion, decreased miRNA-330-3p might contribute to CI in hypertensive patients by decreasing frontal CVR and could be a biomarker of early diagnosis.

Weight reduction ameliorates inflammatory cytokines, adipocytokines and endothelial dysfunction biomarkers among Saudi patients with type 2 diabetes

Background

Type 2 diabetes mellitus (T2DM) considered as one of the cardiovascular disorders (CVD) principle risk factor as diabetes is associated with abnormal levels of endothelial function, inflammatory and adipocytokines.

Objective

The aim of this study was to measure the impact of weight reducing on inflammatory cytokines, adipocytokines and endothelial function biomarkers among obese T2DM patients.

Methods

One-hundred T2DM patients enrolled in the present study; the age range was 35–55 year. Participants shared in this study were enrolled in group (A) received diet control and aerobic exercise on treadmill, while, group (B) had no intervention for 3 months.

Results

The mean values of body mass index (BMI), tumor necrosis factor -alpha (TNF-α), interleukin-6 (IL-6), leptin, inter-cellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), E-selectin and plasminogen activator inhibitor-1 activity (PAI-1 activity) were significantly decreased and adiponectin was increased significantly in the training group, however the results of the control group were not significant. Also, there were significant differences between both groups at the end of the study.

Conclusion

Weight reducing program modulates inflammatory cytokines, adipocytokines and endothelial function biomarkers among obese T2DM patients.

Qingda granule inhibits angiotensin Ⅱ induced VSMCs proliferation through MAPK and PI3K/AKT pathways

ETHNOPHARMACOLOGICAL RELEVANCE

The abnormal increase in vascular smooth muscle cell (VSMC) proliferation is widely accepted as the pivotal process in the vascular remodeling of hypertension. Qingda granule (QDG) is simplified from Qingxuan Jiangya Decoction (QXJYD) which has been in usage for a long time as a traditional Chinese medicine formula to treat hypertension based on the theory of traditional Chinese medicine. However, its underlying molecular mechanisms of action remain largely unknown.

AIM OF STUDY

To investigate the therapeutic efficacy of QDG in the attenuation of elevation of blood pressure and proliferation of VSMCs in vivo and in vitro and explore its possible mechanism of action.

MATERIALS AND METHODS

In vivo, we established an angiotensin Ⅱ (Ang Ⅱ)-mediated hypertension model in C57BL/6 mice and orally administered 1.145 g/kg/day of QDG. The systolic and diastolic blood pressures of all mice were measured at the end of the treatment by using the tail-cuff plethysmograph method and CODA™ noninvasive blood pressure system. VSMC proliferation within the aorta was determined by immunohistochemistry. In vitro, primary rat VSMCs were cultured to further verify the effects of QDG on Ang Ⅱ induced VSMC proliferation. Cell proliferation was investigated using cell counting and MTT assays. The protein expression was determined by western blotting.

RESULTS

We found that oral administration of QDG significantly attenuated the elevation of blood pressure and proliferation of VSMCs in Ang Ⅱ-induced hypertensive mice. Moreover, QDG remarkably inhibited Ang Ⅱ-induced primary rat VSMCs proliferation and decreased mitogen-activated protein kinase (MAPK) and PI3K/AKT activity by attenuating the expression of phospho-extracellular signaling-regulated kinase 1/2, phospho-p38, phospho-c-Jun N-terminal kinase and phospho-protein kinase B.

CONCLUSION

Collectively, our findings suggest that QDG attenuates Ang Ⅱ-induced elevation of blood pressure and proliferation of VSMCs through a decrease in the activation of MAPK and PI3K/AKT pathways. Based on this study, we postulate this could be one of the mechanisms whereby QDG effectively controls hypertension.

Puerarin Inhibits Endothelium-Dependent Contractions in Mouse Carotid Arteries

Background

Many bioactive ingredients of medicinal plants are known to produce vaso-protective benefits. Puerarin is one of the major isoflavone glucosides found in the root of kudzu vine and it exerts an anti-inflammatory effect and many other pharmacological actions. However, the mechanism underlying the vascular effect of puerarin is incompletely understood. Therefore, the present study aims to examine how puerarin reduces endothelium-dependent contractions (EDCs) in mouse arteries.

Material/Methods

EDCs were evoked by acetylcholine (ACh) in isolated mouse carotid arteries with intact endothelium pretreated with Nω-NO2-L-Arg-OMe (L-NAME). The arteries were pretreated with puerarin and other pharmacological inhibitors before the addition of cumulative concentrations of ACh. The concentration of several prostaglandins (PGs) was measured by high performance liquid chromatography-coupled spectrometry (HPLC-MS).

Results

EDCs induced by ACh only presented in endothelium-intact arteries pretreated by L-NAME and EDCs were prevented by the treatment with cyclooxygenase (COX) inhibitor indomethacin (3 μmol/L) or thromboxane prostanoid receptor (TP receptor) antagonist S18886 (30 nmol/L). Acute 40-minute treatment with puerarin reduced EDCs in a concentration-dependent manner without affecting U46619-induced contraction. However, treatment with puerarin did not inhibit ACh-induced production of prostaglandins (PGs) in endothelium-intact arteries.

Conclusions

The present results show that puerarin is able to suppress EDCs in mouse carotid arteries, independent of inhibition of TP receptor or COX2-derived PGs.

Partial loss of endothelial nitric oxide leads to increased cerebrovascular beta amyloid

Cerebral amyloid angiopathy (CAA) is present in over half of the elderly population and in 80-90% of Alzheimer's disease (AD) patients. CAA is defined by the deposition of beta amyloid (Aβ) in small cerebral arteries and capillaries. Cardiovascular risk factors are associated with an increased incidence of CAA. We utilized 18-month-old endothelial nitric oxide synthase (eNOS) heterozygous knockout (^+/-) mice, a clinically relevant model of endothelial dysfunction, to examine the role of endothelial nitric oxide (NO) in vascular Aβ accumulation. eNOS^+/- mice had significantly higher vascular levels of Aβ40 (P < 0.05). Aβ42 was not detected. There was no difference in Aβ in brain tissue. Amyloid precursor protein and β-site APP cleavage enzyme 1 protein levels were unaltered, while levels of the α-secretase enzyme, a disintegrin and metalloproteinase 10, were significantly lower in eNOS ^+ /- microvascular tissue (P < 0.05). Insulin degrading enzyme and low-density lipoprotein receptor-related protein 1 were significantly increased in eNOS^+/- microvascular tissue, most likely an adaptive response to locally higher Aβ concentrations. Lastly, catalase and CuZn superoxide dismutase were significantly elevated in eNOS^+/- microvascular tissue (P < 0.05). These data demonstrate decreased availability of endothelial NO leads to increased cerebrovascular concentration of Aβ along with compensatory mechanisms to protect the vasculature.

Warionia saharae induces antihypertensive and vasorelaxant activities through nitric oxide and KATP channels pathways in rats

Background Warionia saharae Bentham & Cosson. is used in traditional medicine to treat many diseases including hypertension. Method The present study was designed to investigate the antihypertensive activity of aqueous extract of Warionia saharae (WSLAE) in anesthetized L-NAME (Nω-L-arginine methyl ester)-induced rats. The acute and sub-chronic effects of WSLAE on systolic, diastolic, mean arterial blood pressure and heart rate (HR) were investigated after oral administration of the extract (100 mg/kg body weight of WSLAE) during 6 h for the acute experiment and during 7 days for the sub-chronic test. In addition the effect of WSLAE on the contractile response of isolated rat aortic rings was tested and the role of the vascular receptors was evaluated using several drugs. Results The results showed that WSLAE induced a significant decrease in the systolic, diastolic, mean arterial blood pressure and HR in both normotensive and hypertensive rats. Furthermore, this extract induced relaxation in rings pre-contracted with Epinephrine (10 µM) or with KCl (100 mM). This vasorelaxant capacity seems to be mediated through inhibition of KATP channels and nitric oxide (NO) synthase pathways. Conclusion This study supports the use of Warionia saharae in the management of hypertension in Moroccan traditional medicine.

Vascular Smooth Muscle Remodeling in Conductive and Resistance Arteries in Hypertension

Cardiovascular disease is a leading cause of death worldwide and accounts for >17.3 million deaths per year, with an estimated increase in incidence to 23.6 million by 2030. ¹ Cardiovascular death represents 31% of all global deaths ² -with stroke, heart attack, and ruptured aneurysms predominantly contributing to these high mortality rates. A key risk factor for cardiovascular disease is hypertension. Although treatment or reduction in hypertension can prevent the onset of cardiovascular events, existing therapies are only partially effective. A key pathological hallmark of hypertension is increased peripheral vascular resistance because of structural and functional changes in large (conductive) and small (resistance) arteries. In this review, we discuss the clinical implications of vascular remodeling, compare the differences between vascular smooth muscle cell remodeling in conductive and resistance arteries, discuss the genetic factors associated with vascular smooth muscle cell function in hypertensive patients, and provide a prospective assessment of current and future research and pharmacological targets for the treatment of hypertension.

Hydrogen sulfide improves endothelial dysfunction in hypertension by activating peroxisome proliferator-activated receptor delta/endothelial nitric oxide synthase signaling

OBJECTIVE

We aimed to elucidate the ameliorative effect of hydrogen sulfide (H2S) on endothelium-dependent relaxation disturbances via peroxisome proliferator-activated receptor delta/endothelial nitric oxide synthase (PPARδ/eNOS) pathway activation in hypertensive patients and rats.

METHODS

Renal arteries were collected from normotensive and hypertensive patients who underwent nephron-sparing surgery. Renal arteries from 37 patients were cultured with or without sodium H2S (NaHS) 50 μmol/l. The rats were randomly divided into four groups: Sham; Sham + NaHS, two kidneys; one clipped (2K1C); and 2K1C + NaHS. Mean arterial pressure was measured by tail-cuff plethysmography. A microvessel recording technique was used to observe the effect of NaHS on endothelium-dependent relaxation. Plasma H2S concentrations were detected using the monobromobimane method. Real-time PCR and western blotting were used to assess mRNA and protein levels of AT1, cystathionine γ-lyase, PPARδ, and phosphor-eNOS. Laser confocal scanning microscopy measured intracellular NO production in human umbilical vein endothelial cells.

RESULTS

NaHS improved endothelial function in hypertensive humans and rats. The 20-week administration of NaHS to 2K1C rats lowered the mean arterial pressure. In human umbilical vein endothelial cells, NaHS improved the AngII-induced production of NO. NaHS upregulated PPARδ expression, increased protein kinase B (Akt) or adenosine monophosphate kinase-activated protein kinase (AMPK) phosphorylation, and enhanced eNOS phosphorylation. A PPARδ agonist could mimic the ameliorative effect of NaHS that was suppressed by PPARδ, AMPK, or Akt inhibition.

CONCLUSION

H2S plays a protective function in renal arterial endothelium in hypertension by activating the PPARδ/PI3K/Akt/eNOS or PPARδ/AMPK/eNOS pathway. H2S may serve as an effective strategy against hypertension.

Angiotensin II-induced redox-sensitive SGLT1 and 2 expression promotes high glucose-induced endothelial cell senescence

High glucose (HG)-induced endothelial senescence and dysfunction contribute to the increased cardiovascular risk in diabetes. Empagliflozin, a selective sodium glucose co-transporter2 (SGLT2) inhibitor, reduced the risk of cardiovascular mortality in type 2 diabetic patients but the protective mechanism remains unclear. This study examines the role of SGLT2 in HG-induced endothelial senescence and dysfunction. Porcine coronary artery cultured endothelial cells (ECs) or segments were exposed to HG (25 mmol/L) before determination of senescence-associated beta-galactosidase activity, protein level by Western blot and immunofluorescence staining, mRNA by RT-PCR, nitric oxide (NO) by electron paramagnetic resonance, oxidative stress using dihydroethidium and glucose uptake using 2-NBD-glucose. HG increased ECs senescence markers and oxidative stress, down-regulated eNOS expression and NO formation, and induced the expression of VCAM-1, tissue factor, and the local angiotensin system, all these effects were prevented by empagliflozin. Empagliflozin and LX-4211 (dual SGLT1/2 inhibitor) reduced glucose uptake stimulated by HG and H₂ O₂ in ECs. HG increased SGLT1 and 2 protein levels in cultured ECs and native endothelium. Inhibition of the angiotensin system prevented HG-induced ECs senescence and SGLT1 and 2 expression. Thus, HG-induced ECs ageing is driven by the local angiotensin system via the redox-sensitive up-regulation of SGLT1 and 2, and, in turn, enhanced glucotoxicity.

Microparticles from Patients Undergoing Percutaneous Coronary Intervention Impair Vasodilatation by Uncoupling Endothelial Nitric Oxide Synthase

OBJECTIVES

Percutaneous coronary interventions (PCIs) save countless acute myocardial infarction (AMI) patients. However, endothelial injury is still an inevitable complication. Circulating microparticles (MPs) play important roles in vascular dysfunction. Whether PCI affects function of MPs remains unclear.

METHODS

MPs were obtained from AMI patients (n = 38) both preoperatively and 24 h after PCI, and healthy subjects (n = 20). MPs origins were tested by flow cytometry. Rat thoracic aortas were incubated with MPs to determine the effects of MPs on phosphorylation of endothelial nitric oxide synthase (eNOS), caveolin-1 expression, eNOS association with heat shock protein 90 (Hsp90), generation of nitric oxide (NO) and superoxide anion (O2), and endothelial-dependent vasodilatation.

RESULTS

Compared with healthy subjects, MP concentrations increased in AMI patients. Undergoing PCI had no further effect on MPs concentration, but it results in increased endothelial-derived MPs proportion and decreased platelet-derived MP ratio. MPs from AMI patients decreased eNOS phosphorylation at Ser1177, increased eNOS phosphorylation at T495 and caveolin-1 expression, decreased eNOS association with Hsp90, decreased NO production but increased (O2) generation, damaged endothelial-dependent vasodilatation. All of these effects of MPs were strengthened by PCI.

CONCLUSIONS

PCI further enhances the vascular injury effect of MPs. Circulating MPs may be a potential therapeutic target for patients undergoing PCI.

The Effect of Soluble Fiber Supplementation on Metabolic Syndrome Profile among Newly Diagnosed Type 2 Diabetes Patients

Diets with high fiber content improve most metabolic syndrome (MetS) profile in non-diabetic individuals, but there is scarce information about the role of fiber intake in patients with the MetS and diabetes. The objective of this study is to determine whether soluble fiber supplementation improve MetS profile for 8 weeks of intervention in newly diagnosed type 2 diabetes (T2D) adult patients. After one week of dietary stabilization phase, 36 newly diagnosed T2D patients were stratified to different strata according to sex, age, fasting blood sugar (FBS), and waist circumference (WC). Then they were randomly allocated into 2 groups. The psyllium group (n = 18) received 10.5 g of psyllium daily for 8 weeks. The control group (n = 18) maintained their regular diet for 8 weeks. Soluble fiber supplementation showed significant reduction in the majority of MetS profile; FBS (43.55 mg/dL, p < 0.001), triglyceride (37.89 mg/dL, p < 0.001), total cholesterol (20.32 mg/dL, p < 0.001), systolic blood pressure (7.50 mmHg, p < 0.001), diastolic blood pressure (2.78 mmHg, p = 0.013), and WC (2.54 cm, p < 0.001) in the intervention group compared with the control group after 8 weeks of intervention. The high-density lipoprotein cholesterol was reduced in both groups, but this reduction was insignificant. The improvement in the MetS profile was enhanced by combining psyllium to the normal diet. Consumption of foods containing moderate amounts of these fibers may improve MetS profile in newly diagnosed T2D patients. This study was registered in Current Controlled Trials (PHRC/HC/28/15).

Naringin ameliorates endothelial dysfunction in fructose-fed rats

High fructose consumption is associated with metabolic disorders including hyperglycemia and dyslipidemia, in addition to endothelial dysfunction. Naringin, a flavonoid present in citrus fruit, has been reported to exhibit lipid lowering, antioxidant, and cardiovascular protective properties. Therefore, the present study investigated the effect of naringin on fructose-induced endothelial dysfunction in rats and its underlying mechanisms. Male Sprague-Dawley rats were given 10% fructose in drinking water for 12 weeks, whereas control rats were fed drinking water alone. Naringin (100 mg/kg) was orally administered to fructose fed rats during the last 4 weeks of the study. Following 12 weeks, blood samples were collected for measurement of blood glucose, serum lipid profile and total nitrate/nitrite (NOx). Vascular function was assessed by isometric tension recording. Aortic expression of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS), and nitrotyrosine were evaluated by western blot analysis. Fructose feeding induced increased levels of blood glucose, total cholesterol, triglyceride, and low density lipoprotein. In rat aortae, fructose reduced acethycholine-induced vasorelaxation, without affecting sodium nitroprusside-induced vasorelaxation. Treatment of fructose-fed rats with naringin restored fructose-induced metabolic alterations and endothelial dysfunction. Fructose-fed rats also exhibited decreased serum NOx level, reduced eNOS and p-eNOS protein expression, and enhanced nitrotyrosine expression in aortae. These alterations were improved by naringin treatment. The results of the present study suggested that naringin treatment preserves endothelium-dependent relaxation in aortae from fructose fed rats. This effect is primarily mediated through an enhanced NO bioavailability via increased eNOS activity and decreased NO inactivated to peroxynitrite in aortae.

Maternal serum uric acid levels and blood pressure during pregnancy: A community-based cohort study

OBJECTIVE

Studies find both very low and high serum uric acid (UA) levels are related to oxidative stress and to conditions such as cardiovascular diseases and chronic kidney disease in the general population. Pregnancy studies have focused only on high maternal UA. In present study, we tested whether unusually high and low levels of maternal serum UA are associated with increases in blood pressure (BP) during pregnancy.

STUDY DESIGN

The Pregnancy Outcomes and Community Health Study enrolled 3019 pregnant women between their 16th-27th week of pregnancy from 52 clinics in 5 Michigan communities (1998-2004). UA levels were measured in maternal blood collected at enrollment from a sub-cohort of 1223 participants. BP was abstracted from prenatal medical records; these analyses used highest recorded diastolic BP (DBP) and its companion systolic BP (SBP). Mean arterial pressure (MAP) was calculated using the formula of (2 × DBP + SBP)/3. Covariates, including maternal race/ethnicity, age at enrollment, education level, medical insurance status, body mass index before pregnancy, parity, smoking during pregnancy, alcohol use during pregnancy, and gestational week at blood collection, were considered as potential confounding variables. Associations between UA levels and BP were evaluated with linear spline or multiple linear regression models. Models' robustness was examined with bootstrap estimation of variance, sensitivity analysis, and 10-fold cross-validation.

RESULTS

Both DBP and MAP had a J-shaped relationship with maternal UA; the breakpoints (nadirs) were 0.153 and 0.161 mmol/L UA, respectively. For DBP versus UA, adjusted regression coefficient (β) = -95.67 (standard error (SE) = 37.67 and p = 0.01) for the left and adjusted β = 48.95 (SE = 9.56 and p < 0.01) for the right; for MAP versus UA, adjusted β = -58.48 (SE = 31.42 and p = 0.06) for the left and adjusted β = 52.23 (SE = 11.39 and p < 0.01) for the right. Maternal SBP followed a positive linear trend with UA levels (adjusted β = 37.75, SE = 12.93, and p < 0.01). All results were robust.

CONCLUSION

Extreme high and low maternal serum UA levels may be informative in studying maternal blood pressure during pregnancy.

The Role of Adenosine A2A Receptor, CYP450s, and PPARs in the Regulation of Vascular Tone

Adenosine is an endogenous mediator involved in a myriad of physiologic functions, including vascular tone regulation. It is also implicated in some pathologic conditions. Four distinct receptor subtypes mediate the effects of adenosine, such as its role in the regulation of the vascular tone. Vascular tone regulation is a complex and continuous process which involves many mechanisms and mediators that are not fully disclosed. The vascular endothelium plays a pivotal role in regulating blood flow to and from all body organs. Also, the vascular endothelium is not merely a physical barrier; it is a complex tissue with numerous functions. Among adenosine receptors, A2A receptor subtype (A2AAR) stands out as the primary receptor responsible for the vasodilatory effects of adenosine. This review focuses on important effectors of the vascular endothelium, including adenosine, adenosine receptors, EETs (epoxyeicosatrienoic acids), HETEs (hydroxyeicosatetraenoic acids), PPARs (peroxisome proliferator-activated receptors), and KATP channels. Given the impact of vascular tone regulation in cardiovascular physiology and pathophysiology, better understanding of the mechanisms affecting it could have a significant potential for developing therapeutic agents for cardiovascular diseases.

Sitagliptin Attenuates Endothelial Dysfunction of Zucker Diabetic Fatty Rats: Implication of the Antiperoxynitrite and Autophagy

Although the contributions of sitagliptin to endothelial function in diabetes mellitus were previously reported, the potential mechanisms still remain undefined. Our research was intended to explore the underlying mechanisms of protective effects of sitagliptin treatment on endothelial dysfunction in Zucker diabetic fatty (ZDF) rats. Male lean nondiabetic Zucker rats were used as control and male obese ZDF rats were randomly divided into ZDF and ZDF + sitagliptin groups. The significant decrease in endothelium-dependent relaxation induced by acetylcholine was observed in mesenteric arteries and thoracic aorta rings of ZDF rats. The administration of sitagliptin restored the vascular function effectively. The morphology study showed severe endothelial injuries in thoracic aortas of ZDF rats, and sitagliptin treatment attenuated these changes. The increased malondialdehyde levels and decreased superoxide dismutase activities in serum of ZDF rats were reversed by sitagliptin treatment. Sitagliptin also increased the expression of endothelial nitric oxide synthase and microtubule-associated protein 1 light chain 3 (LC3) and decreased the expression of inducible nitric oxide synthase, 3-nitrotyrosine, and p62 in ZDF rats. After giving Fe (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride porphyrin pentachloride (FeTMPyP, a peroxynitrite [ONOO^-] scavenger) or sitagliptin to high-glucose (30 mmol/L, 48 hours) cultured human umbilical vein endothelial cells (HUVECs), the increased levels of Beclin-1 and lysosome-associated membrane protein type 2 were detected. Both FeTMPyP and sitagliptin also significantly increased the number of mRFP-GFP-LC3 dots per cell, suggesting that autophagic flux was increased in HUVECs. Our study indicated that sitagliptin treatment can improve the endothelium-dependent relaxation and attenuate the endothelial impairment of ZDF rats. The protective effects of sitagliptin are possibly related to antiperoxynitrite and promoting autophagy.

Treatment with salvianolic acid B restores endothelial function in angiotensin II-induced hypertensive mice

Salvianolic acid B (Sal B) is one of the most abundant phenolic acids derived from the root of Danshen with potent anti-oxidative properties. The present study examined the vasoprotective effect of Sal B in hypertensive mice induced by angiotensin II (Ang II). Sal B (25mg/kg/day) was administered via oral gavage for 11days to Ang II (1.2mg/kg/day)-infused C57BL/6J mice (8-10weeks old). The vascular reactivity (both endothelium-dependent relaxations and contractions) in mouse arteries was examined by wire myography. The production of reactive oxygen species (ROS), protein level and localization of angiotensin AT₁ receptors and the proteins involved in ROS formation were evaluated using dihydroethidium (DHE) fluorescence, lucigenin-enhanced chemiluminescence, immunohistochemistry and Western blotting, respectively. The changes of ROS generating proteins were also assessed in vitro in human umbilical vein endothelial cells (HUVECs) exposed to Ang II with and without co-treatment with Sal B (0.1-10nM). Oral administration of Sal B reversed the Ang II-induced elevation of arterial systolic blood pressure in mice, augmented the impaired endothelium-dependent relaxations and attenuated the exaggerated endothelium-dependent contractions in both aortas and renal arteries of Ang II-infused mice. In addition, Sal B treatment normalized the elevated levels of AT₁ receptors, NADPH oxidase subunits (NOx-2 and NOx-4) and nitrotyrosine in arteries of Ang II-infused mice or in Ang II-treated HUVECs. In summary, the present study provided additional evidence demonstrating that Sal B treatment for 11days reverses the impaired endothelial function and with a marked inhibition of AT₁ receptor-dependent vascular oxidative stress. This vasoprotective and anti-oxidative action of Sal B most likely contributes to the anti-hypertensive action of the plant-derived compound.

Attenuation of blood pressure in spontaneously hypertensive rats by acupuncture was associated with reduction oxidative stress and improvement from endothelial dysfunction

Background

Hypertension can be treated effectively by acupuncture; however, the association between acupuncture and endothelial function remains unknown. This study aimed to investigate the effects of acupuncture on endothelial dysfunction and oxidative stress-related parameters in spontaneously hypertensive animals.

Methods

Eighteen-week-old Wistar–Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) were arbitrarily divided into four groups: WKY control (n = 8), SHR control (n = 8), SHR sham-acupuncture (n = 8) and SHR acupuncture (n = 8). The SHR acupuncture group had electroacupuncture for 6 consecutive weeks on acupoints ST36 and LR3. Blood pressure was monitored during the treatment period, and animals were euthanized at the 6th week. Aortas were harvested for determination of angiotensin II levels, NADPH oxidase activity and nitrate/nitrite levels. The level of reactive oxygen species (ROS) was determined by dihydroethidium (DHE) imaging, and functional studies were performed to assess vascular reactivity. Endothelial nitric oxide synthase was measured by Western blot assay.

Results

Blood pressure at the end of treatment was significantly lower in the SHR acupuncture group (185.0 ± 5.6 mmHg) compared with the SHR sham-acupuncture and the SHR control groups (201.0 ± 5.4 and 197.4 ± 5.9 mmHg, respectively; P < 0.001). Serum angiotensin II level in the SHR control group was significantly higher than in the WKY control group (P < 0.001), while it was significantly attenuated by acupuncture treatment (P = 0.023). DHE staining showed that ROS level was reduced in the aortas (P = 0.0017) and carotid arteries (P = 0.039) of acupuncture-treated SHRs. Biochemical assays showed that acupuncture inhibited the NADPH oxidase activity (P = 0.022) and enhanced antioxidant capacity (P = 0.0039). In functional studies, endothelium-dependent relaxation of aortic rings (P = 0.018) and carotid arteries (P = 0.022) in response to acetylcholine was improved in the SHR acupuncture group. Aortas of SHRs receiving acupuncture also expressed an elevated level of eNOS (P > 0.001) and p-eNOS (P = 0.012) and a reduced nitrotyrosine level (P = 0.0012). The nitrate/nitrite level in aortic tissue was also attenuated after acupuncture (P = 0.0018).

Conclusion

The effects of acupuncture in treating hypertension were associated with reduced oxidative stress, increased nitric oxide bioavailability and endothelial function in SHRs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13020-016-0110-0) contains supplementary material, which is available to authorized users.

Retinal arteriolar remodeling evaluated with adaptive optics camera: Relationship with blood pressure levels

AIM

To research a retinal arterioles wall-to-lumen ratio or lumen diameter cut-off that would discriminate hypertensive from normal subjects using adaptive optics camera.

PATIENTS AND METHODS

One thousand and five hundred subjects were consecutively recruited and Adaptive Optics Camera rtx1™ (Imagine-Eyes, Orsay, France) was used to measure wall thickness, internal diameter, to calculate wall-to-lumen ratio (WLR) and wall cross-sectional area of retinal arterioles. Sitting office blood pressure was measured once, just before retinal measurements and office blood pressure was defined as systolic blood pressure>=140mmHg and diastolic blood pressure>=90mmHg. ROC curves were constructed to determine cut-off values for retinal parameters to diagnose office hypertension. In another population of 276 subjects office BP, retinal arterioles evaluation and home blood pressure monitoring were obtained. The applicability of retinal WLR or diameter cut-off values were compared in patients with controlled, masked, white-coat and sustained hypertension.

RESULTS

In 1500 patients, a WLR>0.31 discriminated office hypertensive subjects with a 0.57 sensitivity and 0.71 specificity. Lumen diameter<78.2μm discriminated office hypertension with a 0.73 sensitivity and a 0.52 specificity. In the other 276 patients, WLR was higher in sustained hypertension vs normotensive patients (0.330±0.06 vs 0.292±0.05; P<0.001) and diameter was narrower in masked hypertensive vs normotensive subjects (73.0±11.2 vs 78.5±11.6μm; P<0.005).

CONCLUSION

A WLR higher than 0.31 is in favour of office arterial hypertension; a diameter under<78μm may indicate a masked hypertension. Retinal arterioles analysis through adaptive optics camera may help the diagnosis of arterial hypertension, in particular in case of masked hypertension.

Protective Effects of Glucagon-like Peptide 1 on Endothelial Function in Hypertension

Vascular endothelial cells play a major role in maintaining cardiovascular homeostasis. Endothelial dysfunction, characterized by reduced endothelium-dependent relaxations or accompanied by enhanced endothelium-dependent contractions, is a hallmark of and plays a pivotal role in the pathogenesis of hypertension. Endothelial dysfunction in hypertension has been linked to decreases in nitric oxide (NO) bioavailability, reflecting the impaired generation of NO and/or the enhanced inactivation of NO by reactive oxygen species. Many of these conditions can be improved by glucagon-like peptide 1 (GLP-1), a proglucagon-derived hormone secreted by intestinal endocrine L-type cells, which is rapidly inactivated by an enzyme dipeptidyl peptidase 4 in circulation. On one hand, GLP-1 analogues or dipeptidyl peptidase 4 inhibitors upregulate endothelial nitric oxide synthase expression and increase endothelial nitric oxide synthase phosphorylation, resulting in improved production of NO and thus endothelium-dependent relaxations. On the other hand, GLP-1 and related agents attenuate endothelium-dependent contractions by reducing reactive oxygen species generation and cyclooxygenase-2 expression. GLP-1 elevating agents and GLP-1 receptor agonists improve endothelial function in hypertension, suggesting that GLP-1 signaling could be a therapeutic target in hypertension-related vascular events.

Irisin relaxes mouse mesenteric arteries through endothelium-dependent and endothelium-independent mechanisms

Irisin, a newly discovered myokine, has been shown to produce modest weight loss and improve glucose intolerance in mice. The purpose of this study was to investigate the effects of irisin on vascular activity and the mechanisms involved. Experiments were performed on mouse mesenteric arteries. We demonstrated that irisin induced relaxation in mesenteric arteries with or without endothelium in a concentration-dependent manner. It was further demonstrated that the irisin-induced vasorelaxation effects on endothelium-intact mesenteric arteries were reduced by pretreatment with Nω-nitro-L-arginine methyl ester (L-NAME) or 1H-[1, 2, 4] oxadizolo [4, 3-a] quinoxalin-1-one (ODQ). However, pretreatment with indomethacin (INDO), a nonselective cyclooxygenase inhibitor did not modulate irisin-induced relaxation. In addition, the contraction due to extracellular Ca(2+) influx and intracellular Ca(2+) release was also inhibited by irisin. In summary, these results suggested that the endothelium-dependent relaxation of irisin is mediated by the nitric oxide (NO)-guanosine 3', 5'-cyclic phosphate (cGMP)-dependent pathway but not the prostaglandin I2 (PGI2)-cyclic adenosine monophosphate (cAMP)-dependent mechanism. Endothelium-independent relaxation may be depend on inhibiting Ca(2+) influx through blocking VDCCs and intracellular Ca(2+) release through both IP3R and RyR channels.

Pretreatment with β-Boswellic Acid Improves Blood Stasis Induced Endothelial Dysfunction: Role of eNOS Activation

Vascular endothelial cells play an important role in modulating anti-thrombus and maintaining the natural function of vascular by secreting many active substances. β-boswellic acid (β-BA) is an active triterpenoid compound from the extract of boswellia serrate. In this study, it is demonstrated that β-BA ameliorates plasma coagulation parameters, protects endothelium from blood stasis induced injury and prevents blood stasis induced impairment of endothelium-dependent vasodilatation. Moreover, it is found that β-BA significantly increases nitric oxide (NO) and cyclic guanosine 3’, 5’-monophosphate (cGMP) levels in carotid aortas of blood stasis rats. To stimulate blood stasis-like conditions in vitro, human umbilical vein endothelial cells (HUVECs) were exposed to transient oxygen and glucose deprivation (OGD). Treatment of β-BA significantly increased intracellular NO level. Western blot and immunofluorescence as well as immunohistochemistry reveal that β-BA increases phosphorylation of enzyme nitric oxide synthase (eNOS) at Ser1177. In addition, β-BA mediated endothelium-dependent vasodilatation can be markedly blocked by eNOS inhibitor L-NAME in blood stasis rats. In OGD treated HUEVCs, the protective effect of β-BA is attenuated by knockdown of eNOS. In conclusion, the above findings provide convincing evidence for the protective effects of β-BA on blood stasis induced endothelial dysfunction by eNOS signaling pathway.

Low Red Blood Cell Vitamin C Concentrations Induce Red Blood Cell Fragility: A Link to Diabetes Via Glucose, Glucose Transporters, and Dehydroascorbic Acid

Strategies to prevent diabetic microvascular angiopathy focus on the vascular endothelium. Because red blood cells (RBCs) are less deformable in diabetes, we explored an original concept linking decreased RBC deformability to RBC ascorbate and hyperglycemia. We characterized ascorbate concentrations from human and mouse RBCs and plasma, and showed an inverse relationship between RBC ascorbate concentrations and deformability, measured by osmotic fragility. RBCs from ascorbate deficient mice were osmotically sensitive, appeared as spherocytes, and had decreased β-spectrin. These aberrancies reversed with ascorbate repletion in vivo. Under physiologic conditions, only ascorbate's oxidation product dehydroascorbic acid (DHA), a substrate for facilitated glucose transporters, was transported into mouse and human RBCs, with immediate intracellular reduction to ascorbate. In vitro, glucose inhibited entry of physiologic concentrations of dehydroascorbic acid into mouse and human RBCs. In vivo, plasma glucose concentrations in normal and diabetic mice and humans were inversely related to respective RBC ascorbate concentrations, as was osmotic fragility. Human RBC β-spectrin declined as diabetes worsened. Taken together, hyperglycemia in diabetes produced lower RBC ascorbate with increased RBC rigidity, a candidate to drive microvascular angiopathy. Because glucose transporter expression, DHA transport, and its inhibition by glucose differed for mouse versus human RBCs, human experimentation is indicated.

Dietary proteins improve endothelial function under fasting conditions but not in the postprandial state, with no effects on markers of low-grade inflammation

Endothelial dysfunction (ED) and low-grade inflammation (LGI) have a role in the development of CVD. The two studies reported here explored the effects of dietary proteins and carbohydrates on markers of ED and LGI in overweight/obese individuals with untreated elevated blood pressure. In the first study, fifty-two participants consumed a protein mix or maltodextrin (3×20 g/d) for 4 weeks. Fasting levels and 12 h postprandial responses of markers of ED (soluble intercellular adhesion molecule 1 (sICAM), soluble vascular cell adhesion molecule 1 (sVCAM), soluble endothelial selectin and von Willebrand factor) and markers of LGI (serum amyloid A, C-reactive protein and sICAM) were evaluated before and after intervention. Biomarkers were also combined into mean Z-scores of ED and LGI. The second study compared 4 h postprandial responses of ED and LGI markers in forty-eight participants after ingestion of 0·6 g/kg pea protein, milk protein and egg-white protein. In addition, postprandial responses after maltodextrin intake were compared with a protein mix and sucrose. The first study showed significantly lower fasting ED Z-scores and sICAM after 4 weeks on the high-protein diet (P≤0·02). The postprandial studies found no clear differences of ED and LGI between test meals. However, postprandial sVCAM decreased more after the protein mix compared with maltodextrin in both studies (P≤0·04). In conclusion, dietary protein is beneficial for fasting ED, but not for fasting LGI, after 4 weeks of supplementation. On the basis of Z-scores, postprandial ED and LGI were not differentially affected by protein sources or carbohydrates.

Chronic black tea extract consumption improves endothelial function in ovariectomized rats

Purpose

Menopause escalates the risk of cardiovascular diseases in women. There is an unmet need for better treatment strategy for estrogen-deficiency-related cardiovascular complications. Here we investigated the impact of chronic black tea extract (BT) consumption on cardiovascular function and lipid metabolism using a rat model of estrogen deficiency.

Methods

Female Sprague–Dawley rats were ovariectomized (OVX) and treated with BT (15 mg/kg/day, 4 weeks; active ingredients: theaflavins) or estrogen (E2) treatment for 4 weeks. Serum was collected for measuring cholesterol, triacylglycerol and estradiol levels. Changes in vascular reactivity were examined. The protein levels of NADPH oxidases were assessed by Western blotting. Reactive oxygen species (ROS) level was measured using dihydroethidium fluorescence imaging. The concentrations of cGMP were measured using ELISA kit.

Results

Aortic rings from control, BT-treated and E2-treated OVX rats exhibited a greater increase in Phe-induced contraction after inhibition of NO synthase compared with those from OVX rats. ACh-induced endothelium-dependent relaxations were augmented in aortae and renal arteries in BT/E2-treated OVX rats than in OVX rats. BT/E2 treatment improved flow-mediated dilatation in small mesenteric resistance arteries of OVX rats. BT/E2 treatment restored the eNOS phosphorylation level and reversed the up-regulation of NADPH oxidases and ROS overproduction in OVX rat aortae. ACh-stimulated cGMP production was significantly elevated in the aortae from BT- and E2-treated rats compared with those from OVX rats. BT/E2 treatment reduced circulating levels of total cholesterol.

Conclusions

The present study reveals the novel benefits of chronic BT consumption to reverse endothelial dysfunction and favorably modifying cholesterol profile in a rat model of estrogen deficiency and provides insights into developing BT as beneficial dietary supplements for postmenopausal women.

Unconjugated bilirubin mediates heme oxygenase-1-induced vascular benefits in diabetic mice

Heme oxygenase-1 (HO-1) exerts vasoprotective effects. Such benefit in diabetic vasculopathy, however, remains unclear. We hypothesize that bilirubin mediates HO-1-induced vascular benefits in diabetes. Diabetic db/db mice were treated with hemin (HO-1 inducer) for 2 weeks, and aortas were isolated for functional and molecular assays. Nitric oxide (NO) production was measured in cultured endothelial cells. Hemin treatment augmented endothelium-dependent relaxations (EDRs) and elevated Akt and endothelial NO synthase (eNOS) phosphorylation in db/db mouse aortas, which were reversed by the HO-1 inhibitor SnMP or HO-1 silencing virus. Hemin treatment increased serum bilirubin, and ex vivo bilirubin treatment improved relaxations in diabetic mouse aortas, which was reversed by the Akt inhibitor. Biliverdin reductase silencing virus attenuated the effect of hemin. Chronic bilirubin treatment improved EDRs in db/db mouse aortas. Hemin and bilirubin reversed high glucose-induced reductions in Akt and eNOS phosphorylation and NO production. The effect of hemin but not bilirubin was inhibited by biliverdin reductase silencing virus. Furthermore, bilirubin augmented EDRs in renal arteries from diabetic patients. In summary, HO-1-induced restoration of endothelial function in diabetic mice is most likely mediated by bilirubin, which preserves NO bioavailability through the Akt/eNOS/NO cascade, suggesting bilirubin as a potential therapeutic target for clinical intervention of diabetic vasculopathy.

Actin cytoskeletal rearrangement and dysfunction due to activation of the receptor for advanced glycation end products is inhibited by thymosin beta 4

KEY POINTS

Thymosin beta 4 (Tβ4 ) attenuates the vascular cellular toxicity induced by advanced glycation end products (AGEs) in human umbilical vein endothelial cells (HUVECs). Tβ4 reduces expression of both the receptor of AGEs (RAGE) and the filamentous actin (F-actin) to globular actin (G-actin) ratio. RAGE expression was regulated by actin cytoskeleton involved in Tβ4 . Tβ4 attenuates the vascular cellular toxicity induced by AGEs via remodelling of the actin cytoskeleton. AGEs attenuate vascular-like tube formation of HUVECs, which is reversed by Tβ4 via remodelling of the actin cytoskeleton.

ABSTRACT

The receptor of advanced glycation end products (RAGE) is a cell-surface receptor that is a key factor in the pathogenesis of diabetic complications, including vascular disorders. Dysfunction of the actin cytoskeleton contributes to disruption of cell membrane repair in response to various type of endothelial cell damage. However, mechanism underlying RAGE remodelling of the actin cytoskeleton, by which globular actin (G-actin) forms to filamentous actin (F-actin), remains unclear. In this study we examined the role of thymosin beta 4 (Tβ4 ) - which binds to actin, blocks actin polymerization, and maintains the dynamic equilibrium between G-actin and F-actin in human umbilical vein endothelial cells (HUVECs) - in the response to RAGE. Tβ4 increased cell viability and decreased levels of reactive oxygen species in HUVECs incubated with AGEs. Tβ4 reduced the expression of RAGE, consistent with a down-regulation of the F-actin to G-actin ratio. The effect of remodelling of the actin cytoskeleton on RAGE expression was clarified by adding Phalloidin, which stabilizes F-actin. Moreover, small interfering RNA was used to determine whether intrinsic Tβ4 regulates RAGE expression in the actin cytoskeleton. The absence of intrinsic Tβ4 in HUVECs evoked actin cytoskeleton disorder and increased RAGE expression. These findings suggest that regulation of the actin cytoskeleton by Tβ4 plays a pivotal role in the RAGE response to AGEs.

Berberine improves endothelial function by inhibiting endoplasmic reticulum stress in the carotid arteries of spontaneously hypertensive rats

Activation of endoplasmic reticulum (ER) stress in endothelial cells leads to increased oxidative stress and often results in cell death, which has been implicated in hypertension. The present study investigated the effects of berberine, a botanical alkaloid purified from Coptidis rhizoma, on ER stress in spontaneously hypertensive rats (SHRs) and the underling mechanism. Isolated carotid arteries from normotensive WKYs and SHRs were suspended in myograph for isometric force measurement. Protein phosphorylations and expressions were determined by Western blotting. Reactive oxygen species (ROS) level was measured by DHE staining. SHR carotid arteries exhibited exaggerated acetylcholine-triggered endothelium-dependent contractions (EDCs) and elevated ROS accumulation compared with WKY arteries. Moreover, Western blot analysis revealed the reduced AMPK phosphorylation, increased eIF2α phosphorylation, and elevated levels of ATF3, ATF6, XBP1 and COX-2 in SHR carotid arteries while these pathological alterations were reversed by 12 h-incubation with berberine. Furthermore, AMPK inhibitor compound C or dominant negative AMPK adenovirus inhibited the effects of berberine on above-mentioned marker proteins and EDCs. More importantly, ROS scavengers, tempol and tiron plus DETCA, or ER stress inhibitors, 4-PBA and TUCDA normalized the elevated levels of ROS and COX-2 expression, and attenuated EDCs in SHR arteries. Taken together, the present results suggest that berberine reduces EDCs likely through activating AMPK, thus inhibiting ER stress and subsequently scavenging ROS leading to COX-2 down-regulation in SHR carotid arteries. The present study thus provides additional insights into the vascular beneficial effects of berberine in hypertension.

Nuciferine relaxes rat mesenteric arteries through endothelium-dependent and -independent mechanisms

BACKGROUND AND PURPOSE

Nuciferine, a constituent of lotus leaf, is an aromatic ring-containing alkaloid, with antioxidative properties. We hypothesize nuciferine might affect vascular reactivity. This study aimed at determining the effects of nuciferine on vasomotor tone and the underlying mechanism

EXPERIMENTAL APPROACH

Nuciferine-induced relaxations in rings of rat main mesenteric arteries were measured by wire myographs. Endothelial NOS (eNOS) was determined by immunoblotting. Intracellular NO production in HUVECs and Ca(2+) level in both HUVECs and vascular smooth muscle cells (VSMCs) from rat mesenteric arteries were assessed by fluorescence imaging.

KEY RESULTS

Nuciferine induced relaxations in arterial segments pre-contracted by KCl or phenylephrine. Nuciferine-elicited arterial relaxations were reduced by removal of endothelium or by pretreatment with the eNOS inhibitor L-NAME or the NO-sensitive guanylyl cyclase inhibitor ODQ. In HUVECs, the phosphorylation of eNOS at Ser(1177) and increase in cytosolic NO level induced by nuciferine were mediated by extracellular Ca(2+) influx. Under endothelium-free conditions, nuciferine attenuated CaCl2-induced contraction in Ca(2+)-free depolarizing medium. In the absence of extracellular calcium, nuciferine relieved the vasoconstriction induced by phenylephrine and the addition of CaCl2. Nuciferine also suppressed Ca(2+) influx in Ca(2+)-free K(+)-containing solution in VSMCs.

CONCLUSIONS AND IMPLICATIONS

Nuciferine has a vasorelaxant effect via both endothelium-dependent and -independent mechanisms. These results suggest that nuciferine may have a therapeutic effect on vascular diseases associated with aberrant vasoconstriction.

Ginsenoside Rb3 attenuates oxidative stress and preserves endothelial function in renal arteries from hypertensive rats

BACKGROUND AND PURPOSE

Panax ginseng is commonly used to treat cardiovascular conditions in Oriental countries. This study investigated the mechanisms underlying the vascular benefits of ginsenoside Rb3 (Rb3) in hypertension.

EXPERIMENTAL APPROACH

Rings of renal arteries were prepared from spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats and were cultured ex vivo for 8 h. Contractile responses of the rings were assessed with myograph techniques. Expression of NADPH oxidases was assessed by Western blotting and immunohistochemistry. Reactive oxygen species (ROS) were measured using dihydroethidium fluorescence imaging and production of NO was determined using the fluorescent NO indicator DAF-FM diacetate in human umbilical vein endothelial cells.

KEY RESULTS

Ex vivo treatment with Rb3 concentration-dependently augmented endothelium-dependent relaxations, suppressed endothelium-dependent contractions and reduced ROS production and expressions of NOX-2, NOX-4 and p67(phox) in arterial rings from SHR. Rb3 treatment also normalized angiotensin II (Ang II)-stimulated elevation in ROS and expression of NOX-2 and NOX-4 in arterial rings from WKY rats. Rb3 inhibited Ang II-induced reduction of NO production and phosphorylation of endothelial NOS in cultures of human umbilical vein endothelial cells. Rb3 also inhibited oxidative stress in renal arterial rings from hypertensive patients or in Ang II-treated arterial rings from normotensive subjects.

CONCLUSION AND IMPLICATIONS

Ex vivo Rb3 treatment restored impaired endothelial function in arterial rings from hypertensives by reversing over-expression of NADPH oxidases and over-production of ROS, and improved NO bioavailability. Our findings suggest that medicinal plants containing Rb3 could decrease oxidative stress and protect endothelial function in hypertension.

Association between human cytomegalovirus antibody levels, and essential hypertension and functional status in elderly Koreans

AIM

To evaluate the relationship between human cytomegalovirus (HCMV) antibody status, and hypertension and functional status among elderly Koreans.

METHODS

Patients aged ≥65 years were prospectively enrolled from March 2011 to February 2012 at a 2000-bed university hospital. We collected data including CD4+ and CD8+ T-lymphocyte count, and functional status by measuring basic activities of daily living and instrumental activities of daily living for all patients. In addition, HCMV immunoglobulin G levels were analyzed using enzyme-linked fluorescent assay.

RESULTS

During the study period, 103 patients (51 men), who were admitted for treatment of infections or other diseases, were enrolled. Multivariate analysis showed that body mass index and HCMV immunoglobulin G antibody titers were independent factors associated with hypertension in elderly patients (OR 1.347, 95% CI 1.113-1.630, P = 0.002; OR 1.023, 95% CI 1.001-1.047, P = 0.042, respectively). In univariate linear correlations, HCMV antibody levels were positively correlated with systolic blood pressure levels (r = 0.303, P = 0.002), CD8+ T-lymphocyte count (r = 0.313, P = 0.001) and instrumental activities of daily living scores (r = 0.217, P = 0.028). In addition, HCMV immunoglobulin G titers were inversely associated with estimated glomerular filtration rate (r = -0.268, P = 0.006). These four variables remained independently significant in multivariate correlation analysis.

CONCLUSION

These findings could provide insight into the important role of HCMV in the pathogenesis of essential hypertension and decreased functional status in the elderly.

Cyclooxygenase-2-dependent oxidative stress mediates palmitate-induced impairment of endothelium-dependent relaxations in mouse arteries

Palmitic acid, one of the saturated free fatty acids, impairs cardiovascular function as manifested by inducing vascular inflammation, apoptosis and over-production of reactive oxygen species (ROS) although the origin for ROS remains unclear. The present study investigated the cellular mechanisms underlying palmitate-induced impairment of endothelial function. Ex vivo treatment in tissue culture with palmitate concentration-dependently attenuated acetylcholine-induced endothelium-dependent relaxations, up-regulated the expression of cyclooxygenase-2 (COX-2) and elevated superoxide formation in mouse aortic endothelial cells (MAECs) measured by dihydroethidium (DHE) staining and electron paramagnetic resonance (EPR) spectroscopy. Superoxide scavengers, COX-2 inhibitor and thromboxane prostanoid (TP) receptor antagonist, but not COX-1 inhibitor reversed the harmful effects of palmitate. Furthermore, palmitate impaired acetylcholine-induced relaxations and raised superoxide in en face endothelium of aortas only from COX-1(-/-) mice but not from COX-2(-/-) mice. Palmitate increased the production and release of TXB2, a stable thromboxane A2 metabolite in mouse aortas, which was abolished by COX-2 inhibitor. Superoxide scavenger did not affect palmitate-induced up-regulated expression of COX-2 in MAECs. Both real time PCR and luciferase reporter gene assay confirmed COX-2 up-regulation in palmitate-treated MAECs and NF-κB was substantially involved in this up-regulation. The present study provides novel evidence that palmitate up-regulates COX-2 through NF-κB-dependent mechanism and resultant COX-2-associated oxidative stress impairs endothelium-dependent relaxations in mouse aortas.

Vascular dysfunction associated with type 2 diabetes and Alzheimer's disease: a potential etiological linkage

The endothelium performs a crucial role in maintaining vascular integrity leading to whole organ metabolic homeostasis. Endothelial dysfunction represents a key etiological factor leading to moderate to severe vasculopathies observed in both Type 2 diabetic and Alzheimer’s Disease (AD) patients. Accordingly, evidence-based epidemiological factors support a compelling hypothesis stating that metabolic rundown encountered in Type 2 diabetes engenders severe cerebral vascular insufficiencies that are causally linked to long term neural degenerative processes in AD. Of mechanistic importance, Type 2 diabetes engenders an immunologically mediated chronic pro-inflammatory state involving interactive deleterious effects of leukocyte-derived cytokines and endothelial-derived chemotactic agents leading to vascular and whole organ dysfunction. The long term negative consequences of vascular pro-inflammatory processes on the integrity of CNS basal forebrain neuronal populations mediating complex cognitive functions establish a striking temporal comorbidity of AD with Type 2 diabetes. Extensive biomedical evidence supports the pivotal multi-functional role of constitutive nitric oxide (NO) production and release as a critical vasodilatory, anti-inflammatory, and anti-oxidant, mechanism within the vascular endothelium. Within this context, we currently review the functional contributions of dysregulated endothelial NO expression to the etiology and persistence of Type 2 diabetes-related and co morbid AD-related vasculopathies. Additionally, we provide up-to-date perspectives on critical areas of AD research with special reference to common NO-related etiological factors linking Type 2 diabetes to the pathogenesis of AD.

Variable reactive hyperemia in normotensive strains of rat

Previous studies from our laboratory report variation in nitric oxide (NO)‐dependent arterial pressure within the same strain of normotensive Sprague–Dawley rat dependent upon the commercial vendor supplying the rats. Clinical assessment of endothelial NO activity and endothelial function in general has used postocclusion, flow‐mediated dilation (FMD). Therefore, this study was conducted to determine whether the reactive hyperemic response was different between two normotensive strains from two different suppliers, Sprague–Dawley (SD) and Wistar–Kyoto (WKY) rats from Charles River (CR) and Harlan Laboratories (H), respectively. Rats were anesthetized and the femoral artery was occluded for 5 min, with femoral blood flow measured continuously by use of an ultrasonic perivascular flow probe. The average area under the reactive hyperemic response curve (3‐min duration) was not different between SD rats from CR (80 ± 23 mL/min∙s; n = 6) and H (94 ± 16 mL/min∙s; n = 6). As previously reported, blood pressures were higher in the SD rats from H versus CR. WKY rats from both suppliers had significantly larger hyperemia; 371 ± 67 versus 281 ± 71 mL/min∙s (n = 5) for the CR and H WKY rats, respectively, but again, were not different between vendors. Blood pressures in WKY rats were similar between vendors. These results suggest that differences in NO bioactivity are not discernable with an adapted FMD protocol in the rat and that normotensive strains of rat can have large differences in reactive hyperemia despite having similar blood pressures.

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Much of the scientific literature presumes that the physiology of so‐called normal rat strains is identical even when obtained from different suppliers. We demonstrate here that the blood flow response in the hindlimb of the rat to acute ischemia shows consistency within a given strain, but vary tremendously from different strains of rat even though both are considered “normal” control strains, the Sprague–Dawley and Wistar–Kyoto rats.

Salidroside stimulates mitochondrial biogenesis and protects against H₂O₂-induced endothelial dysfunction

Salidroside (SAL) is an active component of Rhodiola rosea with documented antioxidative properties. The purpose of this study is to explore the mechanism of the protective effect of SAL on hydrogen peroxide- (H₂O₂-) induced endothelial dysfunction. Pretreatment of the human umbilical vein endothelial cells (HUVECs) with SAL significantly reduced the cytotoxicity brought by H₂O₂. Functional studies on the rat aortas found that SAL rescued the endothelium-dependent relaxation and reduced superoxide anion (O2^∙−) production induced by H₂O₂. Meanwhile, SAL pretreatment inhibited H₂O₂-induced nitric oxide (NO) production. The underlying mechanisms involve the inhibition of H₂O₂-induced activation of endothelial nitric oxide synthase (eNOS), adenosine monophosphate-activated protein kinase (AMPK), and Akt, as well as the redox sensitive transcription factor, NF-kappa B (NF-κB). SAL also increased mitochondrial mass and upregulated the mitochondrial biogenesis factors, peroxisome proliferator-activated receptor gamma-coactivator-1alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) in the endothelial cells. H₂O₂-induced mitochondrial dysfunction, as demonstrated by reduced mitochondrial membrane potential (Δψm) and ATP production, was rescued by SAL pretreatment. Taken together, these findings implicate that SAL could protect endothelium against H₂O₂-induced injury via promoting mitochondrial biogenesis and function, thus preventing the overactivation of oxidative stress-related downstream signaling pathways.