Endothelium-dependent Vascular Function Research Articles

Sildenafil attenuates oxidative stress and endothelial dysfunction in lead-induced hypertension.

Lead (Pb) reduces NO bioavailability, impairs the antioxidant system, and increases the generation of reactive oxygen species (ROS). Pb-induced oxidative stress may be responsible for the associated endothelial dysfunction. Sildenafil has shown nitric oxide (NO)-independent action, including antioxidant effects. Therefore, we examined the effects of sildenafil on oxidative stress, reductions of NO and endothelial dysfunction in Pb-induced hypertension. Wistar rats were distributed into three groups: Pb, Pb + sildenafil and Sham. Blood pressure and endothelium-dependent vascular function were recorded. We also examined biochemical determinants of lipid peroxidation and antioxidant function. ROS levels, NO metabolites and NO levels in human umbilical vein endothelial cells (HUVECs) were also evaluated. Sildenafil prevents impairment of endothelium-dependent NO-mediated vasodilation and attenuates Pb-induced hypertension, reduces ROS formation, enhances superoxide dismutase (SOD) activity and antioxidant capacity in plasma and increases NO metabolites in plasma and HUVECs culture supernatants, while no changes were found on measurement of NO released from HUVECs incubated with plasma of the Pb and Pb + sildenafil groups compared with the sham group. In conclusion, sildenafil protects against ROS-mediated inactivation of NO, thus preventing endothelial dysfunction and attenuating Pb-induced hypertension, possibly through antioxidant effects.

Cardiovascular dysfunction induced by combined exposure to nicotine inhalation and high fat diet

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and smoking remains the most significant preventable risk factor. The contribution of nicotine, the addictive component of all tobacco products, to smoking-related CVD remains poorly understood. In addition to smoking, obesity is also a major risk factor for the development of CVD. Recent studies indicate that individuals who are overweight or obese are at greater risk of nicotine product usage. With more than 40% of the US population affected by obesity, the combined effects of obesity and nicotine on cardiovascular (CV) health warrant urgent investigation. In the present study we investigated the combined effects of nicotine exposure and a high fat diet (HFD) on CV function.Male C57BL/6N mice (8 wk-old) were placed on either a HFD (60 kcal% Fat) or standard chow (SC, 22 kcal% Fat) and exposed to room air (RA) or nicotine vapor (NIC, 12 hr/day during the active phase) for 10 weeks (n=10-15/group). Mice with HFD exposure alone exhibited significantly greater weight gain at 10 weeks vs. SC-RA controls (122.5±9.8% increase in body weight in HFD-RA vs. 40.7±3.3% in SC-RA, p < 0.0001), whereas concurrent nicotine inhalation significantly reduced this weight gain (66.5±5.8% in HFD-NIC group, p < 0.0001). In the HFD-NIC group, blood pressure (BP) monitoring via telemetry (24 hours) revealed non-significant increases in BP in the inactive phase, coupled with a significant (p < 0.05) reduction in the expected dipping in BP during the inactive compared to the active phase (HFD-NIC: 4.5±1.2; SC-RA: 11.3±2.2; HFD-RA: 12.4±1.0 and SC-NIC: 9.7±4.6 mmHg). LV catheterization showed that mice exposed to both nicotine and HFD had elevated LV end diastolic pressure (HFD-NIC: 14.1±0.7; SC-RA: 4.5±0.8; HFD-RA: 2.8±0.7 and SC-NIC: 3.9±1.3 mmHg; p<0.05) and prolonged time constant of LV relaxation (Tau). LV RNAseq analysis revealed that HFD-NIC resulted in 70 differentially expressed genes (36 upregulated and 34 downregulated) unique from nicotine or HFD alone, with multiple differentially regulated pathways including dilated cardiomyopathy signaling pathway (p = 2.8E-04). Plasma NT-pro-BNP levels were significantly increased in HFD-RA mice vs. SC-RA controls, whereas this response was absent in HFD-NIC. Finally, HFD+NIC led to greater impairment of endothelium-dependent vasorelaxation in thoracic aortas compared to either treatment alone.In conclusion, although nicotine reduced HFD-induced weight gain, combined exposure to inhaled nicotine and HFD led to greater cardiovascular dysfunction including dysregulation in physiological blood pressure responses, LV diastolic dysfunction, and greater impairment of endothelial-dependent vascular function. National Institute of Health [grant numbers HL135635 (to JDG, EL and XY); HL146098, HL146514, and HL151398 (to DJL.); and F30HL160071 (to AKW)]; Department of Veterans Affairs (BX004294 to EL) and the American Heart Association [Award 829761 (to AKW) and Award 20POST35200075 (to ZL)]. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Prevalence of hs-CRP among Indians with hypertension.

The prevalence of hypertension in the early twentieth century varied in India, ranging from 2-15% in Urban India and 2-8% in Rural India. In the inter heart and inter stroke study, hypertension accounted for 17.9% and 34.6% of population attributable risk for coronary artery disease and stroke respectively. CRP appears in serum in response to a variety of inflammatory stimuli .Raised level of hs-CRP is seen with increasing with age, during an infection, inflammation, coronary artery diseases, obesity, sepsis, smoking and vasculitis. CRP is also a factor in the development of atherosclerotic plaque. Although CRP was believed to be a marker of vascular inflammation, recent research indicates that it plays an active role in atherogenesis. So in this study we measured serum hs- CRP in patients with essential hypertension and correlated with blood pressure. The study consists of 50 patients with essential hypertension with antihypertensive medications. in the age group of 40 to 60 years of both sexes and 25 normotensive subjects with no history of cardiovascular, neoplastic, hepatic, renal, infectious or auto immune disease. IHEC clearance and informed consent were obtained. hs-CRP was measured by ELISA kit. Our study showed significantly elevated serum hs-CRP level in hypertensive subjects in comparison with control subjects. To find out the relationship between physiological and biochemical parameters with CRP Pearson correlation coefficient has been applied. The level of significance has been fixed as 5% (p<0.05). SPSS15 software has been used for calculation. Our study showed significantly elevated serum hs-CRP level in hypertensive subjects in comparison with control subjects. But there is no correlation of hs-CRP level with both systolic and diastolic pressure. Several studies have shown inflammatory markers such as CRP as an independent determinant of endothelium dependent vascular function among patient with coronary heart disease (CHD) in patients with hypertension. There was no significant correlation was observed between levels of hs-CRP and systolic and diastolic blood pressure in this study but there was a significant elevation hs-CRP level was observed in hypertensive patients.

Prenatal exposure to a low dose of BPS causes sex-dependent alterations to vascular endothelial function in adult offspring.

Background: Bisphenol S (BPS) is among the most commonly used substitutes for Bisphenol A (BPA), an endocrine disrupting chemical used as a plasticizer in the manufacture of polycarbonate plastics and epoxy resins. Bisphenols interfere with estrogen receptor (ER) signaling, which modulates vascular function through stimulation of nitric oxide (NO) production via endothelial nitric oxide synthase (eNOS). BPS can cross into the placenta and accumulates in the fetal compartment to a greater extent than BPA, potentially interfering with key developmental events. Little is known regarding the developmental impact of exposure to BPA substitutes, particularly with respect to the vasculature. Objective: To determine if prenatal BPS exposure influences vascular health in adulthood. Methods: At the time of mating, female C57BL/6 dams were administered BPS (250 nM) or vehicle control in the drinking water, and exposure continued during lactation. At 12-week of age, mesenteric arteries were excised from male and female offspring and assessed for responses to an endothelium-dependent (acetylcholine, ACh) and endothelium-independent (sodium nitroprusside, SNP) vasodilator. Endothelium-dependent dilation was measured in the presence or absence of L-NAME, an eNOS inhibitor. To further explore the role of NO and ER signaling, wire myography was used to assess ACh responses in aortic rings after acute exposure to BPS in the presence or absence of L-NAME or an ER antagonist. Results: Increased ACh dilation and increased sensitivity to Phe were observed in microvessels from BPS-exposed females, while no changes were observed in male offspring. Differences in ACh-induced dilation between control or BPS-exposed females were eliminated with L-NAME. Increased dilatory responses to ACh after acute BPS exposure were observed in aortic rings from female mice only, and differences were eliminated with inhibition of eNOS or inhibition of ER. Conclusion: Prenatal BPS exposure leads to persistent changes in endothelium-dependent vascular function in a sex-specific manner that appears to be modulated by interaction of BPS with ER signaling.

Endothelial dysfunction caused by circulating microparticles from diabetic mice is reduced by PD98059 through ERK and ICAM-1

Endothelial dysfunction contributes to the development of diabetic complications and the production of circulating microparticles (MPs). Our previous study showed that diabetic mice-derived MPs (DM MPs) had increased levels of extracellular regulated protein kinase 1/2 (ERK1/2) and impaired endothelial-dependent relaxation in aortas when compared with control mice-derived MPs. This study was designed to investigate whether PD98059, an ERK1/2 inhibitor, affects the function of aortas and DM MPs. MPs were obtained from streptozotocin-induced DM, DM after PD98059 treatment, and ICR mice as control. The mice and MPs were then analyzed on the basis of their vascular function and enzyme expressions. Compared with the controls, platelet-derived MPs and ERK1/2 levels in the MPs were significantly elevated in the DM but showed little change in PD98059-treated DM. PD98059 mainly decreased ERK1/2 phosphorylation in the MPs. In the aortas of DM and DM MPs the endothelium-dependent vascular function was impaired, and there was a significantly greater improvement in the vascular function in the PD98059-treated DM aortas and the aortas treated with PD98059-treated DM MPs than in DM aortas and the aortas treated with DM MPs. Furthermore, DM MPs increased ERK1/2 and intracellular adhesion molecule-1 (ICAM-1) expressions in the aortas, but PD98059-treated DM MPs did not show these effects. For the first time, these results indicate that PD98059 treatment improves endothelial dysfunction in DM, and adhesion properties of DM MPs can be partly blocked by PD98059 via ERK and ICAM-1. These effects may explain some of the vascular complications in diabetes.

P-058. A comparison of the effects of placenta-derived extracellular vesicles from preeclamptic and uncomplicated pregnancies on endothelial-dependent vascular function

P-058. A comparison of the effects of placenta-derived extracellular vesicles from preeclamptic and uncomplicated pregnancies on endothelial-dependent vascular function

Increased bioavailability of phenolic acids and enhanced vascular function following intake of feruloyl esterase-processed high fibre bread: A randomized, controlled, single blind, crossover human intervention trial

Clinical trial data have indicated an association between wholegrain consumption and a reduction in surrogate markers of cardiovascular disease. Phenolics present in wholegrain bound to arabinoxylan fibre may contribute these effects, particularly when released enzymatically from the fiber prior to ingestion. The aim of the present study was therefore to determine whether the intake of high fibre bread containing higher free ferulic acid (FA) levels (enzymatically released during processing) enhances human endothelium-dependent vascular function. A randomized, single masked, controlled, crossover, human intervention study was conducted on 19 healthy men. Individuals consumed either a high fibre flatbread with enzymatically released free FA (14.22mg), an equivalent standard high fibre bread (2.34mg), or a white bread control (0.48mg) and markers of vascular function and plasma phenolic acid concentrations were measured at baseline, 2, 5 and 7h post consumption. Significantly increased brachial arterial dilation was observed following consumption of the high free FA ('enzyme-treated') high fibre bread verses both a white bread (2h: p<0.05; 5h: p<0.01) and a standard high fibre bread (5h: p<0.05). Concurrently, significant increases in plasma FA levels were observed, at 2h (p<0.01) after consumption of the enzyme-treated bread, relative to control treatments. Blood pressure, heart rate, DVP-SI and DVP-RI were not significantly altered following intake of any of the breads (p>0.05). Dietary intake of bread, processed enzymatically to release FA from arabinoxylan fiber during production increases the bioavailability of FA, and induces acute endothelium-dependent vasodilation. NO: NCT03946293. WEBSITE: www.clinicaltrials.gov.

SUMO2 regulates vascular endothelial function and oxidative stress in mice.

SUMOylation is a posttranslational modification of lysine residues. Modification of proteins by small ubiquitin-like modifiers (SUMO)1, -2, and -3 can achieve varied, and often unique, physiological and pathological effects. We looked for SUMO2-specific effects on vascular endothelial function. SUMO2 expression was upregulated in the aortic endothelium of hypercholesterolemic low-density lipoprotein receptor-deficient mice and was responsible for impairment of endothelium-dependent vasorelaxation in these mice. Moreover, overexpression of SUMO2 in aortas ex vivo, in cultured endothelial cells, and transgenically in the endothelium of mice increased vascular oxidative stress and impaired endothelium-dependent vasorelaxation. Conversely, inhibition of SUMO2 impaired physiological endothelium-dependent vasorelaxation in normocholesterolemic mice. These findings indicate that while endogenous SUMO2 is important in maintenance of normal endothelium-dependent vascular function, its upregulation impairs vascular homeostasis and contributes to hypercholesterolemia-induced endothelial dysfunction.NEW & NOTEWORTHY Sumoylation is known to impair vascular function; however, the role of specific SUMOs in the regulation of vascular function is not known. Using multiple complementary approaches, we show that hyper-SUMO2ylation impairs vascular endothelial function and increases vascular oxidative stress, whereas endogenous SUMO2 is essential for maintenance of normal physiological function of the vascular endothelium.

Investigating the lowest threshold of vascular benefits from LDL cholesterol lowering with a PCSK9 mAb inhibitor (alirocumab) in healthy volunteers – a mechanistic physiological study (INTENSITY-LOW): protocol and study rationale

Objective: Whether reducing low density lipoprotein cholesterol (LDL-C) is associated with cardiovascular benefits in low risk normocholesterolaemic subjects is unknown. The INTENSITY LOW [Investigating the lowest threshold of vascular benefits from LDL-cholesterol lowering with a PCSK9 mAb inhibitor (alirocumab) in healthy volunteers] study aims to assess whether lowering LDL-C by alirocumab monotherapy can improve endothelial-dependent vascular function compared with placebo (primary objective) in low-risk normocholesterolaemic healthy individuals. Changes in endothelial-dependent or endothelial-independent vascular function, arterial stiffness and biomarkers of systemic inflammation by alirocumab, atorvastatin or their combination are secondary objectives.Study design and methods: This is a single-center, randomized, two-period, single-blind, placebo-controlled clinical trial. The study was registered on clinicaltrials.gov (N03273972).It will include 30 healthy low-risk subjects with LDL-C < 4.1 mmol/l. After passing the screening visit (Visit 1), eligible participants will be randomized 1:1 to either subcutaneous alirocumab 150 mg or placebo. These will be administered as single doses in 2 visits 14 days apart (Visits 2 and 3). Atorvastatin 20 mg once nightly will be prescribed for 14 days at Visit 3 in both groups through to Visit 4.At baseline (Visit 2) and during all post-dose visits (Visits 3–4), endothelial function will be assessed using venous occlusion plethysmography. Specifically, changes in forearm blood flow responses to intra-arterial infusions of acetylcholine, sodium nitroprusside and L-NG-monomethyl-arginine acetate will be assessed as surrogates of endothelial-dependent and -independent vasodilatation. Additionally, arterial stiffness and carotid intima-media thickness will be evaluated at the same timepoints. The above-mentioned changes will be correlated with changes in lipid and systemic inflammation biomarkers.

Time Course Of Acute Exercise-induced Impairment Of Endothelial Dependent Vasorelaxation

Regular endurance exercise improves endothelium dependent vasorelaxation. However, the initial stress of acute exercise may impair vascular function prior to the beneficial adaptive response. PURPOSE: The purpose of this study is to examine the effects of acute exhaustive exercise on endothelial-dependent vascular function. METHODS: 7-9 mo old, male, Wistar rats were divided into four groups (n=6/group): sedentary (SED), 6h post-exercise (6h), 24h post-exercise, and 48h post-exercise. Exercise consisted of one bout of exhaustive treadmill exercise lasting between 30–40 min. Endothelium dependent vasorelaxation was assessed in ring segments of the aorta by constructing an acetycholine dose response curve (10−10-10−5 M) in a wire myograph. RESULTS: Maximal vasorelexation was impaired in 6h (70.1+5.2%) and 24h (76.2+4.4%) compared to SED (86.9+4.2%) and 48h (83.7+4.4%). EC50 for 6h (3.9e−7) was significantly (p<0.05) greater than SED (1.3e−7) and 48h (1.5e−7). CONCLUSIONS: These data suggest that acute, exhaustive treadmill exercise results in impaired endothelial dependent vasorelaxation up to 24h post-exercise and returns to sedentary levels within 48h.

Comparison Of The Brachial And Popliteal Artery Vascular Responses To The Consumption Of A High Fat Meal

Results from earlier studies indicate that the consumption of a high fat meal (HFM) significantly reduces the vascular reactivity (i.e. decreased vasodilatory response) in the brachial artery. Given the prevalence of vascular disease in the lower extremities, it is interesting that there is little data to date comparing the effect of consuming a HFM on the vascular responses of the upper and lower limbs. PURPOSE: To compare the vascular response of the brachial (BA) and popliteal (PA) arteries following the consumption of a HFM. It is hypothesized that endothelial dysfunction induced by the consumption of a HFM will be greater in the PA than in the BA, consistent with the findings that the lower extremities are more susceptible to endothelial dysfunction and vascular disease compared to the upper extremities. METHODS: Eight healthy (23.8 ± 1.8 yrs (±SD)) men (n=3) and women (n=5) reported to the facility following a 12 h fast. Each subject rested in either the supine (BA) or prone position (PA) to obtain baseline measurements of the artery of interest. Endothelial-dependent vascular function was assesses using the flow-mediated vasodilation (FMD) technique. Each subject consumed a high fat meal consisting of 90g total fat (63 g saturated fat), 364 mg cholesterol, 17 g carbohydrate and 139 mg sodium. BA and PA FMD responses were obtained 60 min following ingestion of the HFM. Longitudinal images of the BA and PA were obtained in B-mode using a linear array probe with an operating frequency of 7.0 MHz. Images were captured (10 fps) and analyzed using a commercially available system that incorporates an automated wall detection program. FMD (%) was calculated as the difference between baseline diameter and the maximal diameter measured following release of the occlusion cuff (250 mmHg) placed around the forearm for 5 min. RESULTS: Compared to baseline, consumption of a HFM resulted in a decrease (p<0.05) in vascular reactivity for both the BA (pre, 10.6 ± 3.7 vs. post, 6.2 ± 2.2 %FMD) and the PA (pre, 4.8 ± 2.1 vs. post, 2.1 ± 1.2 %FMD). When expressed as relative to the change in FMD within a limb, the decrease in the PA (55.3%) was greater (p<0.05) than for the BA (42.4%). CONCLUSIONS: While the differences in the FMD response to a HFM between the BA and PA artery are apparent, the mechanism behind this difference warrants further investigation

High soluble endoglin levels do not induce endothelial dysfunction in mouse aorta.

Increased levels of a soluble form of endoglin (sEng) circulating in plasma have been detected in various pathological conditions related to cardiovascular system. High concentration of sEng was also proposed to contribute to the development of endothelial dysfunction, but there is no direct evidence to support this hypothesis. Therefore, in the present work we analyzed whether high sEng levels induce endothelial dysfunction in aorta by using transgenic mice with high expression of human sEng. Transgenic mice with high expression of human sEng on CBAxC57Bl/6J background (Sol-Eng +) and age-matched transgenic littermates that do not develop high levels of human soluble endoglin (control animals in this study) on chow diet were used. As expected, male and female Sol-Eng + transgenic mice showed higher levels of plasma concentrations of human sEng as well as increased blood arterial pressure, as compared to control animals. Functional analysis either in vivo or ex vivo in isolated aorta demonstrated that the endothelium-dependent vascular function was similar in Sol-Eng + and control mice. In addition, Western blot analysis showed no differences between Sol-Eng + and control mice in the protein expression levels of endoglin, endothelial NO-synthase (eNOS) and pro-inflammatory ICAM-1 and VCAM-1 from aorta. Our results demonstrate that high levels of soluble endoglin alone do not induce endothelial dysfunction in Sol-Eng + mice. However, these data do not rule out the possibility that soluble endoglin might contribute to alteration of endothelial function in combination with other risk factors related to cardiovascular disorders.

Vascular effects of aerobic exercise training in rat adult offspring exposed to hypoxia-induced intrauterine growth restriction.

Prenatal hypoxia, one of the most common consequences of complicated pregnancies, leads to intrauterine growth restriction (IUGR) and impairs later-life endothelium-dependent vascular function. Early interventions are needed to ultimately reduce later-life risk for cardiovascular disease. Aerobic exercise training has been shown to prevent cardiovascular diseases. Whether exercise can be used as an intervention to reverse the vascular phenotype of this susceptible population is unknown. Aerobic exercise training enhanced endothelium-derived hyperpolarization-mediated vasodilatation in gastrocnemius muscle arteries in male IUGR offspring, and did not improve nitric oxide-mediated vasodilatation in IUGR offspring. Understanding the mechanisms by which exercise impacts the cardiovascular system in a susceptible population and the consideration of sexual dimorphism is essential to define whether exercise could be used as a preventive strategy in this population. Hypoxia in utero is a critical insult causing intrauterine growth restriction (IUGR). Adult offspring born with hypoxia-induced IUGR have impaired endothelium-dependent vascular function. We tested whether aerobic exercise improves IUGR-induced endothelial dysfunction. Pregnant Sprague-Dawley rats were exposed to control (21% oxygen) or hypoxic (11% oxygen) conditions from gestational day 15 to 21. Male and female offspring from normoxic and hypoxic (IUGR) pregnancies were randomized at 10weeks of age to either an exercise-trained or sedentary group. Exercise-trained rats ran on a treadmill for 30min at 20mmin(-1) , 5deg gradient, 5daysweek(-1) , for 6weeks. Concentration-response curves to phenylephrine and methylcholine were performed in second order mesenteric and gastrocnemius muscle arteries, in the presence or absence of l-NAME (100μm), MnTBAP (peroxynitrite scavenger; 10μm), apamin (0.1μm) and TRAM-34 (an intermediate-conductance calcium-activated potassium channel blocker; 10μm), or indomethacin (5μm). In adult male IUGR offspring, prenatal hypoxia had no effect on total vasodilator responses in either vascular bed. Aerobic exercise training in IUGR males, however, improved endothelium-derived hyperpolarization (EDH)-mediated vasodilatation in gastrocnemius muscle arteries. Female IUGR offspring had reduced NO-mediated vasodilatation in both vascular beds, along with decreased total vasodilator responses and increased prostaglandin-mediated vasoconstriction in gastrocnemius muscle arteries. In contrast to males, aerobic exercise training in IUGR female offspring had no effect on either vascular bed. Exercise may not prove to be a beneficial therapy for specific vascular pathways affected by prenatal hypoxia, particularly in female offspring.

Rosuvastatin treatment in stable chronic obstructive pulmonary disease (RODEO): a randomized controlled trial.

The objective of this study was to examine whether statin therapy is associated with enhanced endothelium-dependent vascular function, improved pulmonary function and reduced systemic inflammation in patients with chronic obstructive pulmonary disease (COPD). This randomized, placebo-controlled, double-blind, parallel trial including patients with COPD was performed at two University hospitals in Norway. Patients with stable COPD (n = 99) were assigned randomly to receive rosuvastatin 10 mg (n = 49) or matching placebo (n = 50) once daily for 12 weeks. The primary outcome measure was change in endothelium-dependent vascular function measured using peripheral arterial tonometry and expressed as the reactive hyperaemia index. Secondary end-points were change in pulmonary function, as assessed by forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC), and change in the circulating levels of the inflammatory markers interleukin-6 (IL6) and high-sensitivity C-reactive protein (hsCRP). In the overall study population, no significant between-group difference in change in endothelium-dependent vascular or pulmonary function was observed. Rosuvastatin therapy was associated with a reduction in hsCRP (-20% vs. 11%, P = 0.017) and an attenuation of the rise in IL6 concentration (8% vs. 30%, P = 0.028) compared with placebo. In a prespecified subgroup analysis of patients with a supra-median circulating hsCRP concentration (>1.7 mg L(-1) ), rosuvastatin was associated with improved endothelium-dependent vascular function (13% vs. 2%, P = 0.026). In stable COPD patients without the standard indications for statin therapy, rosuvastatin treatment is associated with a significant attenuation of systemic inflammation and improvement in endothelial-dependent vascular function in patients with evidence of systemic inflammation.

Lingonberry juice lowers blood pressure of spontaneously hypertensive rats (SHR)

Lingonberries (Vaccinium vitis-idaea) are rich in polyphenols, such as proanthocyanidins, anthocyanins, flavonols and flavanols. Polyphenol-rich foods affect vascular health. We previously described improved endothelium-dependent vascular function as well as anti-inflammatory and anti-atherothrombotic effects in spontaneously hypertensive rats (SHR) fed with lingonberry juice. In the present study, we investigated the effects of lingonberry juice dose on blood pressure, vascular function and vascular inflammation in SHR in an 8weeks’ study. Diluted (1:5) cold-compressed lingonberry juice was given as drinking fluid ad libitum to 5week old SHR for 8weeks. Control group (SHR) and normotensive reference group (Wistar-Kyoto) received tap water. Systolic blood pressure (SBP) was monitored weekly. Function of mesenteric artery rings was assessed in standard organ-bath chambers after 8weeks. Biochemical and clinical chemistry variables were measured from plasma and urine. Lingonberry juice lowered SBP of SHR (p=0.007). Endothelium-dependent vascular relaxation was not improved. Lingonberry treatment slightly affected plasma inflammatory markers (reduction of NOx and sICAM-1) and clinical chemistry variables (decreased alkaline phosphatase and increased chloride and calcium levels). In conclusion, Lingonberry juice at small concentrations lowers blood pressure in a long-term treatment in SHR.

Assessing Murine Resistance Artery Function Using Pressure Myography

Pressure myograph systems are exquisitely useful in the functional assessment of small arteries, pressurized to a suitable transmural pressure. The near physiological condition achieved in pressure myography permits in-depth characterization of intrinsic responses to pharmacological and physiological stimuli, which can be extrapolated to the in vivo behavior of the vascular bed. Pressure myograph has several advantages over conventional wire myographs. For example, smaller resistance vessels can be studied at tightly controlled and physiologically relevant intraluminal pressures. Here, we study the ability of 3rd order mesenteric arteries (3-4 mm long), preconstricted with phenylephrine, to vaso-relax in response to acetylcholine. Mesenteric arteries are mounted on two cannulas connected to a pressurized and sealed system that is maintained at constant pressure of 60 mmHg. The lumen and outer diameter of the vessel are continuously recorded using a video camera, allowing real time quantification of the vasoconstriction and vasorelaxation in response to phenylephrine and acetylcholine, respectively. To demonstrate the applicability of pressure myography to study the etiology of cardiovascular disease, we assessed endothelium-dependent vascular function in a murine model of systemic hypertension. Mice deficient in the α1 subunit of soluble guanylate cyclase (sGCα1-/-) are hypertensive when on a 129S6 (S6) background (sGCα1-/-S6) but not when on a C57BL/6 (B6) background (sGCα1-/-B6). Using pressure myography, we demonstrate that sGCα1-deficiency results in impaired endothelium-dependent vasorelaxation. The vascular dysfunction is more pronounced in sGCα1-/-S6 than in sGCα1-/-B6 mice, likely contributing to the higher blood pressure in sGCα1-/-S6 than in sGCα1-/-B6 mice. Pressure myography is a relatively simple, but sensitive and mechanistically useful technique that can be used to assess the effect of various stimuli on vascular contraction and relaxation, thereby augmenting our insight into the mechanisms underlying cardiovascular disease.

Assessing Murine Resistance Artery Function Using Pressure Myography

Pressure myograph systems are exquisitely useful in the functional assessment of small arteries, pressurized to a suitable transmural pressure. The near physiological condition achieved in pressure myography permits in-depth characterization of intrinsic responses to pharmacological and physiological stimuli, which can be extrapolated to the in vivo behavior of the vascular bed. Pressure myograph has several advantages over conventional wire myographs. For example, smaller resistance vessels can be studied at tightly controlled and physiologically relevant intraluminal pressures. Here, we study the ability of 3(rd) order mesenteric arteries (3-4 mm long), preconstricted with phenylephrine, to vaso-relax in response to acetylcholine. Mesenteric arteries are mounted on two cannulas connected to a pressurized and sealed system that is maintained at constant pressure of 60 mmHg. The lumen and outer diameter of the vessel are continuously recorded using a video camera, allowing real time quantification of the vasoconstriction and vasorelaxation in response to phenylephrine and acetylcholine, respectively. To demonstrate the applicability of pressure myography to study the etiology of cardiovascular disease, we assessed endothelium-dependent vascular function in a murine model of systemic hypertension. Mice deficient in the α1 subunit of soluble guanylate cyclase (sGCα1(-/-)) are hypertensive when on a 129S6 (S6) background (sGCα1(-/-S6)) but not when on a C57BL/6 (B6) background (sGCα1(-/-B6)). Using pressure myography, we demonstrate that sGCα1-deficiency results in impaired endothelium-dependent vasorelaxation. The vascular dysfunction is more pronounced in sGCα1(-/-S6) than in sGCα1(-/-B6) mice, likely contributing to the higher blood pressure in sGCα1(-/-S6) than in sGCα1(-/-B6) mice. Pressure myography is a relatively simple, but sensitive and mechanistically useful technique that can be used to assess the effect of various stimuli on vascular contraction and relaxation, thereby augmenting our insight into the mechanisms underlying cardiovascular disease.

Redox Factor-1 Activates Endothelial SIRTUIN1 through Reduction of Conserved Cysteine Sulfhydryls in Its Deacetylase Domain

Apurinic/Apyrmidinic Endonuclease 1/Redox Factor-1 (APE1/Ref-1) is a reductant which is important for vascular homeostasis. SIRTUIN1 (SIRT1) is a lysine deacetylase that also promotes endothelium-dependent vasorelaxation. We asked if APE1/Ref-1 governs the redox state and activity of SIRT1, and whether SIRT1 mediates the effect of APE1/Ref-1 on endothelium-dependent vascular function. APE1/Ref-1 maintains sulfhydryl (thiol) groups of cysteine residues in SIRT1 in the reduced form and promotes endothelial SIRT1 activity. APE1/Ref-1 stimulates SIRT1 activity by targeting highly conserved vicinal thiols 371 and 374 which form a zinc tetra-thiolate motif in the deacetylase domain of SIRT1. Cysteine residues in the N-terminal redox domain of APE1/Ref-1 are essential for reducing SIRT1 and stimulating its activity. APE1/Ref-1 protects endothelial SIRT1 from hydrogen peroxide-induced oxidation of sulfhydryls and from inactivation. APE1/Ref-1 also promotes lysine deacetylation of the SIRT1 target endothelial nitric oxide synthase (eNOS). SIRT1 mutated at cysteines 371 and 374, which renders it non-reducible by APE1/Ref-1, prevents lysine deacetylation of eNOS by APE1/Ref-1. SIRT1 free thiol (reduced sulfhydryl) content and deacetylase activity are diminished in all examined tissues of APE1/Ref-1+/− mice, including the vasculature. Overexpression of SIRT1 in aortas of APE1/Ref-1+/− mice restores endothelium-dependent vasorelaxation and bioavailable nitric oxide (NO) to levels similar to those observed in wild-type mice. Thus, APE1/Ref-1, by maintaining functionally important cysteine sulfhydryls in SIRT1 in the reduced form, promotes endothelial SIRT1 activity. This reductive activation of endothelial SIRT1 by APE1/Ref-1 mediates the effect of APE1/Ref-1 on eNOS acetylation, promoting endothelium-derived NO and endothelium-dependent vasorelaxation.

Preservation of Endothelial Vascular Function of Saphenous Vein Grafts after Long-Time Storage with a Recently Developed Potassium-Chloride and N-Acetylhistidine Enriched Storage Solution

Saphenous vein grafts are still commonly used in cardiac, vessel and also in transplant surgery. In cardiac surgery, a desperate graft situation could force to keep nonutilized explanted vein segments after CABG in reserve for case of early graft failure. Historically there were no options for adequate long-time graft storage protecting the endothelial layer with its important antithrombotic and immunosuppressive functional aspects. Commonly isotonic saline solution (sodium chloride [NaCl]) has been used as a storing solution in this case. We investigated the impact of long-time storage in NaCl and a recently developed potassium-chloride and N-acetylhistidine enriched storage solution (TiProtec, Dr. Köhler Chemie, Germany) on endothelial function of saphenous veins. Saphenous vein segments (n = 19) were intraoperatively isolated and stored for 24 and 96 hours. The segments were examined in a Mulvany-myograph to assess vessel function. Following preconstriction with norepinephrine, dose-response curves were assessed for relaxation with bradykinin and sodium-nitroprusside. We compared developed maximum wall tension and endothelial cell and smooth muscle cell (SMC) dependent vasodilatory function. Maximum vessel wall tension was significantly better preserved in TiProtec-stored vessels after 24 h in comparison to segments stored in NaCl (5.11 ± 4.79 mN/mm vs. 2.48 ± 2.43 mN/mm; p = 0.033) and 96 h (4.94 ± 2.82 mN/mm vs. 2.80 ± 1.76 mN/mm; p = 0.042). Likewise endothelium-derived vasodilatory function was maintained significantly after 24 hours in TiProtec-stored vessels (36.9 ± 2.6% vs. 11.8 ± 30.9%; p = 0.005). After 96 hours, endothelium-dependent vascular function was nearly abolished in NaCl-stored vessels, but largely preserved in TiProtec-stored segments (20.6 ± 2.9% vs. 1.9 ± 4.3% in NaCl; p = 0.015). Sodium nitroprusside-mediated SMC-vasodilatory function was better maintained after 24 hours of storage in TiProtec group (88.8 ± 6.4% vs. 61.3 ± 8.2%; p = 0.009). After 96 hours of storage, SMC relaxation did not significantly differ between both storage groups which might be due to a distinct reduction of contractile function in NaCl-stored vessels (98.6 ± 5.0% and 77.9 ± 10.5% for Tiprotec and NaCl, respectively). Vessel functions comprising contraction, endothelium-dependent and -independent vasodilatation are significantly reduced following 24 hours of cold storage in NaCl. After 96 hours of storage in NaCl these functions are nearly totally abolished. TiProtec is able to largely reduce this loss of function during cold storage. Therefore, TiProtec is a feasible option for longer term storage of saphenous vein grafts in CABG vessel and transplant surgery.

OS075. Endothelial-dependent vascular function is significantly impaired in obesity and restored by overexpression of DDAH1: Evidence for the role of ADMA

Obesity is a significant independent risk factor for preeclampsia. Vascular dysfunction is a central pathophysiological feature of preeclampsia. Vascular dysfunction is common in obesity. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase and metabolized primarily by the enzyme DDAH1. ADMA is significantly elevated in obesity and preeclampsia. The focus of this study was to investigate the role of elevated ADMA in obesity-mediated vascular dysfunction. Endothelial-dependent and independent- vascular function of mesenteric arteries was assessed using an isometric myograph. Arteries from pregnant female C57/B6J control lean (n=7), control obese (n=12), DDAH1 overexpressing lean (n=6) and DDAH1 obese (n=10) mice were investigated. Obesity was induced by a high fat diet (42% fat, with adjusted calories, Harlan Teklad) for 8 weeks prior to mating. Data were analyzed by repeated measures ANOVA with significance at p<0.05. DDAH1 transgenic mice and control wild-type mice both increased body weight significantly on the high fat diet compared to lean mice (p<0.01). Obese mice also evidenced significantly elevated leptin concentrations (control obese= 4.1ng/ml and DDAH1 obese 3.9ng/ml) compared to lean mice (1.1ng/ml, p<0.05) reflecting increased adiposity. Contractile response to phenylephrine was not different between arteries from all groups of pregnant mice, however tension was greater in arteries from control obese mice compared to control lean mice (p<0.01). Methacholine-induced endothelial-dependent relaxation was significantly blunted in arteries from control obese mice (66±14%) compared to control lean mice (93±2%, p<0.001). In contrast, endothelial-dependent relaxation was intact in arteries from DDAH1 obese mice (90±8%). Endothelial-dependent relaxation was restored in arteries from control obese mice by ex-vivo incubation with L-arginine (91±9%). Endothelial-dependent relaxation was not different between arteries from all groups of mice in the presence of the nitric oxide synthase inhibitor L-NAME. Similarly, endothelial-independent relaxation in response to nitroprusside was not different between arteries from all groups of mice. Overexpression of the ADMA metabolizing enzyme DDAH1 is protective of the obesity-mediated loss in endothelial-dependent relaxation. These data suggest that elevated ADMA is a significant contributor to vascular dysfunction in pregnancy. This project supported by National Institutes of Health grant R01-HL091094.