Independent Vascular Function Research Articles

No accelerated arterial aging in relatively young women after preeclampsia as compared to normotensive pregnancy.

IntroductionPreeclampsia, an endothelial disorder of pregnancy, predisposes to remote cardiovascular diseases (CVD). Whether there is an accelerated effect of aging on endothelial decline in former preeclamptic women is unknown. We investigated if the arterial aging regarding endothelial-dependent and -independent vascular function is more pronounced in women with a history of preeclampsia as compared to women with a history of solely normotensive gestation(s).MethodsData was used from the Queen of Hearts study (ClinicalTrials.gov Identifier NCT02347540); a large cross-sectional study on early detection of cardiovascular disease among young women (≥18 years) with a history of preeclampsia and a control group of low-risk healthy women with a history of uncomplicated pregnancies. Brachial artery flow-mediated dilation (FMD; absolute, relative and allometric) and sublingually administered nitroglycerine-mediated dilation (NGMD; absolute and relative) were measured using ultrasound. Cross-sectional associations of age with FMD and NGMD were investigated by linear regression. Models were adjusted for body mass index, smoking, antihypertensive drug use, mean arterial pressure, fasting glucose, menopausal state, family history of CVD and stress stimulus during measurement. Effect modification by preeclampsia was investigated by including an interaction term between preeclampsia and age in regression models.ResultsOf the 1,217 included women (age range 22–62 years), 66.0% had a history of preeclampsia and 34.0% of normotensive pregnancy. Advancing age was associated with a decrease in relative FMD and NGMD (unadjusted regression coefficient: FMD: −0.48%/10 years (95% CI:−0.65 to −0.30%/10 years), NGMD: −1.13%/10 years (−1.49 to −0.77%/10 years)) and increase in brachial artery diameter [regression coefficient = 0.16 mm/10 years (95% CI 0.13 to 0.19 mm/10 years)]. Similar results were found when evaluating FMD and NGMD as absolute increase or allometrically, and after confounder adjustments. These age-related change were comparable in former preeclamptic women and controls (p-values interaction ≥0.372). Preeclampsia itself was independently associated with consistently smaller brachial artery diameter, but not with FMD and NGMD.ConclusionIn young- to middle-aged women, vascular aging in terms of FMD and NGMD was not accelerated in women after preeclampsia compared to normotensive pregnancies, even though former preeclamptic women consistently have smaller brachial arteries.

Relation of vascular dilator function and cardiac autonomic function with coronary angiography findings in patients with non-ST segment elevation acute coronary syndrome.

A sizeable number of patients with a diagnosis of non-ST segment elevation acute coronary syndrome show non-obstructive coronary artery disease. In this study we assessed whether differences in vascular and cardiac autonomic function exist between non-ST segment elevation acute coronary syndrome patients with obstructive or non-obstructive coronary artery disease. Systemic endothelium-dependent and independent vascular dilator function (assessed by flow-mediated dilation and nitrate-mediated dilation of the brachial artery, respectively) and cardiac autonomic function (assessed by time-domain and frequency-domain heart rate variability parameters) were assessed on admission in 120 patients with a diagnosis of non-ST segment elevation acute coronary syndrome. Patients were divided into two groups according to coronary angiography findings: (a) 59 (49.2%) with obstructive coronary artery disease (≥50% stenosis in any epicardial arteries); (b) 61 (50.8%) with non-obstructive coronary artery disease. No significant differences between the two groups were found in both flow-mediated dilation (5.03 ± 2.6 vs. 5.40 ± 2.5%, respectively; P = 0.37) and nitrate-mediated dilatation (6.79 ± 2.8 vs. 7.30 ± 3.4%, respectively; P = 0.37). No significant differences were also observed between the two groups both in time-domain and frequency-domain heart rate variability variables, although the triangular index tended to be lower in obstructive coronary artery disease patients (30.2 ± 9.5 vs. 33.9 ± 11.6, respectively; P = 0.058). Neither vascular nor heart rate variability variables predicted the recurrence of angina, requiring emergency room admission or re-hospitalisation, during 11.3 months of follow-up. Among patients admitted with a diagnosis of non-ST segment elevation acute coronary syndrome we found no significant differences in systemic vascular dilator function and cardiac autonomic function between those with obstructive coronary artery disease and those with non-obstructive coronary artery disease.

Peripheral Microvascular Function Reflects Coronary Vascular Function.

Objectives- Coronary endothelial dysfunction is a precursor of atherosclerosis and adverse outcomes. Whether endothelial dysfunction is a localized or generalized phenomenon in humans remains uncertain. We simultaneously measured femoral and coronary vascular function with the hypothesis that peripheral vascular endothelial function will be reflective of coronary endothelial function. Approach and Results- Eighty-five subjects underwent coronary angiography for evaluation of chest pain or abnormal stress tests. Endothelium-dependent and -independent vascular function were measured using intracoronary and intrafemoral infusions of acetylcholine and sodium nitroprusside, respectively. Coronary flow reserve was assessed using intracoronary adenosine infusion. Flow velocity was measured in each circulation using a Doppler wire (FloWire, EndoSonics). Coronary vascular resistance and femoral vascular resistance were calculated as mean arterial pressure (mm Hg)/coronary blood flow (mL/min) and mean arterial pressure (mm Hg)/femoral average peak velocity (cm/s), respectively. Mean age was 53±11 years, 37% were female, 44% had hypertension, 12% had diabetes mellitus, and 38% had obstructive coronary artery disease. There was a correlation between the change in femoral vascular resistance with acetylcholine and acetylcholine-mediated changes in both the coronary vascular resistance ( r=0.27; P=0.014) and in the epicardial coronary artery diameter ( r=-0.25; P=0.021), indicating that subjects with normal endothelial function in the femoral circulation had normal endothelial function in the coronary epicardial and microcirculation and vice versa. The coronary vasodilator response to adenosine also correlated with the femoral vasodilatation with acetylcholine ( r=0.4; P=0.0002). There was no correlation between the coronary and femoral responses to sodium nitroprusside. Conclusions- Endothelial functional changes in the peripheral and coronary circulations were modestly correlated. Thus, peripheral microvascular endothelial function reflects endothelium-dependent coronary epicardial and microvascular function and the coronary flow reserve. Visual Overview- An online visual overview is available for this article.

Exercise, but not statins improve endothelial function in obese rats

IntroductionStatins and exercise training (ET) improve endothelial function. The mechanisms by which statins in combination with ET alter vascular function are largely unknown. We investigated how statins influence the effects of ET on vascular function in obese rats.MethodsEight‐week‐old male Wistar rats (n = 46) received a high‐fat diet for 20 weeks. The rats were randomized after into four groups after eight weeks: sedentary (SED; n =11), exercise (EX; n=11), statin (STAT; n=13) and exercise with statin (EX/STAT; n=11). Simvastatin (10mg/d/kg) was administered in drinking water. The rats exercised for 12 weeks, 5 days/week for 1 h/day at 18 m/min. Endothelium‐dependent (acetylcholine [Ach]) and – independent (sodium‐nitroprusside [SNP]) vascular function was assessed in the abdominal aorta using in vitro myography. Gene expression and protein abundance of nitric‐oxide soluble guanylate cyclase (NO‐sGC) signaling was assessed using q‐PCR and Western blot.ResultsStatin treatment significantly reduced cholesterol levels and did not influence exercise duration or intensity. ET independent of statins improved endothelium dependent vasodilation in EX and EX/STAT compared to SED and STAT, respectively. In untreated rats ET did not alter SNP vasodilation. However, in statin treated animals, ET improved SNP vasodilation. ET and statins increased NO protein abundance by 40% and 80%, respectively, compared to SED. However, in treated rats ET reduced NO to 40% above SED. Protein phosphatase 1 regulatory subunit 14A (CPI17), an inhibitor protein of smooth muscle myosin phosphatase showed a significant statin and exercise interaction at gene expression level (p < .0001). In untreated rats, ET upregulated CPI17 gene expression by 50% (p < .05). In treated rats a downregulation of 35% (p < .05) was observed. The results were similar on the protein level. The myosin phosphatase target subunit 1 (MYPT1) which drives the cGMP independent smooth muscle myosin phosphatase calcium desensitization was increased due to statin treatment (40%) and not affected by ET. Statin reduced sGCα protein content by more than 80%. Protein kinase cGMP‐dependent 1 (PRKG1), which phosphorylates multiple targets implicated in modulating cellular calcium was significantly increased (50%; p < .05) in non‐treated but decreased in treated rats. Protein abundance of the sarco/endoplasmic reticulum Ca2+‐ATPase (SERCA), which drives the uptake of calcium into the sarcoplasmic reticulum was reduced by statins (50%) and not rescued by ET.ConclusionET independent of statin treatment improved endothelium‐dependent vasodilation. Interestingly, in untreated animals these improvements were most likely driven by NO, while in animals receiving statins, ET altered vascular smooth muscle calcium handling and desensitization. Overall our results suggests that individuals receiving statins should exercise to maintain vascular health.Support or Funding InformationDZHK (German Centre for Cardiovascular Research)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

166. Multiple pregnancy significantly impairs maternal vascular function postpartum

Introduction Cardiovascular disease (CVD) is significantly increased among women with previous adverse pregnancy outcomes, particularly preeclampsia. Data suggest that the increased risk of CVD among women with pregnancy hypertension such as preeclampsia is driven primarily by shared common risk factors that precede pregnancy. However, paradoxically data also indicate that a history of multiple uncomplicated pregnancies alone is associated with an increased risk of future CVD compared to never pregnant women. Objective The focus of this project was to begin to investigate the effect of pregnancy itself on future maternal vascular function. Methods Female apoE - / - mice were bred 1, 2 or 3 times and compared to age matched (10 months of age) female virgin apoE - / - mice (n = 8–9/group). Blood pressure was measured by tail cuff. Endothelial-dependent and independent vascular function of mesenteric arteries was assessed using an isometric myograph. Results Plasma cholesterol levels were similarly elevated in all apoE - / - mice. Blood pressure was significantly elevated in the mice bred 3× (138 ± 29/94 ± 13) compared to virgin mice (118 ± 12/83 ± 10 mmHg, p 0.01). Contractile response and tension to phenylephrine was not different between arteries from virgin and 1, 2, or 3× prior pregnant apoE - / - mice. Methacholine-induced endothelial-dependent relaxation was significantly blunted in arteries from 2 and 3× prior pregnant mice (62 ± 5 and 60 ± 7%, respectively) compared to 1× prior pregnant (77 ± 8%) and virgin mice (83 ± 9%, p 0.001). Endothelial-dependent relaxation was not different between arteries in the presence of the nitric oxide synthase inhibitor L-NAME. Similarly, endothelial-independent relaxation in response to nitroprusside was not different between virgin and prior pregnant mice. Discussion Compared to virgin apoE - / - female mice, similarly aged mice with multiple previous pregnancies have higher blood pressure and blunted endothelial-dependent relaxation. These data support epidemiologic data identifying an association between prior pregnancy (multiple) and increased risk of future maternal heart disease. Funded by the AHA 16SFRN27810001.

Nitrate decreases xanthine oxidoreductase-mediated nitrite reductase activity and attenuates vascular and blood pressure responses to nitrite

Nitrite and nitrate restore deficient endogenous nitric oxide (NO) production as they are converted back to NO, and therefore complement the classic enzymatic NO synthesis. Circulating nitrate and nitrite must cross membrane barriers to produce their effects and increased nitrate concentrations may attenuate the nitrite influx into cells, decreasing NO generation from nitrite. Moreover, xanthine oxidoreductase (XOR) mediates NO formation from nitrite and nitrate. However, no study has examined whether nitrate attenuates XOR-mediated NO generation from nitrite. We hypothesized that nitrate attenuates the vascular and blood pressure responses to nitrite either by interfering with nitrite influx into vascular tissue, or by competing with nitrite for XOR, thus inhibiting XOR-mediated NO generation. We used two independent vascular function assays in rats (aortic ring preparations and isolated mesenteric arterial bed perfusion) to examine the effects of sodium nitrate on the concentration-dependent responses to sodium nitrite. Both assays showed that nitrate attenuated the vascular responses to nitrite. Conversely, the aortic responses to the NO donor DETANONOate were not affected by sodium nitrate. Further confirming these results, we found that nitrate attenuated the acute blood pressure lowering effects of increasing doses of nitrite infused intravenously in freely moving rats. The possibility that nitrate could compete with nitrite and decrease nitrite influx into cells was tested by measuring the accumulation of nitrogen-15-labeled nitrite (15N-nitrite) by aortic rings using ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS). Nitrate exerted no effect on aortic accumulation of 15N-nitrite. Next, we used chemiluminescence-based NO detection to examine whether nitrate attenuates XOR-mediated nitrite reductase activity. Nitrate significantly shifted the Michaelis Menten saturation curve to the right, with a 3-fold increase in the Michaelis constant. Together, our results show that nitrate inhibits XOR-mediated NO production from nitrite, and this mechanism may explain how nitrate attenuates the vascular and blood pressure responses to nitrite.

Effect of Angiotensin II Type I Receptor Blockade with Valsartan on Carotid Artery Atherosclerosis: A Double Blind Randomized Clinical Trial Comparing Valsartan and Placebo (EFFERVESCENT)

Progression of atherosclerosis is associated with a greater risk for adverse outcomes. Angiotensin II plays a key role in the pathogenesis and progression of atherosclerosis. We aimed to investigate the effects of angiotensin II type-1 receptor blockade with Valsartan on carotid wall atherosclerosis, with the hypothesis that Valsartan will reduce progression of atherosclerosis. Subjects (n = 120) with carotid intima-media thickness >0.65 mm by ultrasound were randomized (2:1) in a double-blind manner to receive either Valsartan or placebo for 2 years. Bilateral T2-weighted black-blood carotid magnetic resonance imaging was performed at baseline, 12 and 24 months. Changes in the carotid bulb vessel wall area and wall thickness were primary endpoints. Secondary endpoints included changes in carotid plaque thickness, plasma levels of aminothiols, C-reactive protein, fibrinogen, and endothelium-dependent and -independent vascular function. Over 2 years, the carotid bulb vessel wall area decreased with Valsartan (-6.7, 95% CI [-11.6, -1.9] mm(2)) but not with placebo (3.4, 95% CI [-2.8, 9.6] mm(2)), P = .01 between groups. Similarly, mean wall thickness decreased with Valsartan (-0.18, 95% CI [-0.30, -0.06] mm), but not with placebo (0.08, 95% CI [-0.07, 0.23] mm), P = .009 between groups. Furthermore, plaque thickness decreased with Valsartan (-0.35, 95% CI [-0.63, -0.08] mm) but was unchanged with placebo (+0.28, 95% CI [-0.11, 0.69] mm), P = .01 between groups. These findings were unaffected by statin therapy or changes in blood pressure. Notably, there were significant improvements in the aminothiol cysteineglutathione disulfide, and trends to improvements in fibrinogen levels and endothelium-independent vascular function. In subjects with carotid wall thickening, angiotensin II type-1 receptor blockade was associated with regression in carotid atherosclerosis. Whether these effects translate into improved outcomes in subjects with subclinical atherosclerosis warrants investigation.

119-POS

Objectives Coffee consumption is associated with a significant decreased risk of CVD and a decreased risk of preeclampsia, however the mechanism behind this relationship is unknown. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase and metabolized primarily by the enzyme DDAH1. ADMA is an independent risk factor of CVD among low-, medium- and high-risk patients, and significantly elevated in hypercholesterolemia and preeclampsia. The focus of this study was to investigate if caffeine treatment affects circulating levels of ADMA and vascular function in the hypercholesterolemia apo E−/− mouse, which is known to have elevated ADMA. Methods Female apo E−/− mice were treated with caffeine (10 μg/day) via drinking water for 7 days. Endothelial-dependent and independent-vascular function from caffeine treated (n = 5) and control (n = 5) mice were investigated. Plasma ADMA, SDMA, arginine, cholesterol, triglycerides and blood pressure were measured. Results ADMA was significantly lower in caffeine treated mice (0.09 ± 0.04 vs. 0.24 ± 0.05 μ mol/L, p Conclusions Acute caffeine treatment in female hypercholesterolemic apo E−/− mice is associated with lower ADMA, a decrease in blood pressure and a significant improvement in endothelial-dependent relaxation in the absence of changes in circulating cholesterol. The potential beneficial effects of coffee consumption on cardiovascular risk and preeclampsia may be related to changes in the metabolism of ADMA. Disclosures R. Powers: None. P. Kukunas: None. M. Gallaher: None.

Vascular function and mortality in haemodialysis patients: A pilot study

Haemodialysis patients often have impaired vascular function that can contribute to mortality. Endothelial-dependent and -independent vascular function can be assessed using the brachial artery reactivity (BAR) technique that measures flow-mediated dilatation (FMD) and the response to glyceryl trinitrate (GTN), respectively. The aim of this pilot study was to determine whether BAR measurements in haemodialysis patients were associated with mortality. Brachial artery responses to FMD and administration of GTN were assessed in consecutive haemodialysis patients. Patients were then followed up to 18 months after BAR measurements. Seventeen patients were included in the study. After 18 months of follow-up, patients were divided into two groups: survived (n=12) and deceased (n=5). Patients who survived had a significantly greater median percentage vasodilatation to GTN than those who died (19.1% vs 8.8%; P=0.04); and a significantly greater median area under the diameter change-time curve (318 vs 146 mm/s; P=0.03). However, there were no significant differences between survivors and deceased in median percentage vasodilation to FMD (6.0% vs 4.3%; P=0.21), time to peak dilation (45 vs 40s; P=0.66) or area under the diameter change-time curve (35.5 vs 20 mm/s; P=0.29). In this pilot study in a small group of haemodialysis patients, endothelial-independent vasodilatory response to GTN was associated with mortality and was of better prognostic value than the endothelial-dependent response to FMD. This finding needs to be investigated in a larger cohort.

Vascular, metabolic, and inflammatory abnormalities in normoglycemic offspring of patients with type 2 diabetes mellitus

Endothelial dysfunction, insulin resistance, and elevated levels of circulating proinflammatory markers are among the earliest detectable abnormalities in people at risk for atherosclerosis. Accelerated atherosclerosis is a leading contributor to morbidity and mortality in type 2 diabetes mellitus, a complex genetic disorder. Therefore, we hypothesized that normoglycemic offspring of patients with type 2 diabetes mellitus (NOPD) may have impaired vascular and metabolic function related to an enhanced proinflammatory state. We compared NOPD (n = 51) with matched healthy control subjects without family history of diabetes (n = 35). Flow- and nitroglycerin-mediated brachial artery vasodilation were assessed by ultrasound to evaluate endothelium-dependent and -independent vascular function. Each subject also underwent an oral glucose tolerance test to evaluate metabolic function. Fasting levels of plasma adiponectin and circulating markers of inflammation (high-sensitivity C-reactive protein, CD40 ligand, interleukin 1 β, tumor necrosis factor α, vascular cell adhesion molecule 1, and intracellular adhesion molecule) were measured. Both NOPD and the control group had fasting glucose and insulin levels well within the reference range. However, results from oral glucose tolerance test and quantitative insulin sensitivity check index revealed that NOPD were insulin resistant with significantly impaired flow- and nitroglycerin-mediated dilation compared with the control group. Adiponectin levels were lower, whereas many circulating markers of inflammation were higher, in NOPD compared with the control group. Normoglycemic offspring of patients with type 2 diabetes mellitus have impaired vascular and metabolic function accompanied by an enhanced proinflammatory state that may contribute to their increased risk of diabetes and its vascular complications.

Lack of Endothelial Nitric Oxide Synthase Promotes Endothelin-Induced Hypertension

Endothelin-1 (ET-1) is one of the most potent biologic vasoconstrictors. Nevertheless, transgenic mice that overexpress ET-1 exhibit normal BP. It was hypothesized that vascular effects of ET-1 may be antagonized by an increase of the endothelial counterpart of ET-1, nitric oxide (NO), which is produced by the endothelial NO synthase (eNOS). Therefore, cross-bred animals of ET transgenic mice (ET+/+) and eNOS knockout (eNOS-/-) mice and were generated, and BP and endothelial function were evaluated in these animals. Endothelium-dependent and -independent vascular function was assessed as relaxation/contraction of isolated preconstricted aortic rings. The tissue ET and NO system was determined in aortic rings by quantitative real-time PCR and Western blotting. Systolic BP was similar in ET+/+ and wild-type (WT) mice but was significantly elevated in eNOS-/- mice (117 +/- 4 mmHg versus 94 +/- 6 mmHg in WT mice; P < 0.001) and even more elevated in ET+/+ eNOS-/- cross-bred mice (130 +/- 4 mmHg; P < 0.05 versus eNOS-/-). Maximum endothelium-dependent relaxation was enhanced in ET+/+ mice (103 +/- 6 versus 87 +/- 4% of preconstriction in WT littermates; P < 0.05) and was completely blunted in eNOS-/- (-3 +/- 4%) and ET+/+ eNOS-/- mice (-4 +/- 4%), respectively. Endothelium-independent relaxation was comparable among all groups. Quantitative real-time PCR as well as Western blotting revealed an upregulation of the aortic ET(A) and ET(B) receptors in ET+/+ eNOS-/-, whereas eNOS was absent in aortic rings of eNOS-/- and ET+/+ eNOS-/- mice. ET-1 aortic tissue concentrations were similar in WT mice and ET+/+ eNOS-/- mice most probably as a result of an enhanced clearance of ET-1 by the upregulated ET(B) receptor. These data show for the first time that in transgenic mice that overexpress human ET-1, additional knockout of eNOS results in a further enhancement of BP as compared with eNOS-/- mice. The human ET+/+ eNOS-/- mice therefore represent a novel model of hypertension as a result of an imbalance between the vascular ET-1 and NO systems.

Impaired vascular function in normoglycemic mice prone to autoimmune diabetes: Role of nitric oxide

Type 1 diabetes is an immuno-inflammatory condition which increases the risk of cardiovascular disease, particularly in young adults. This study investigated whether vascular function is altered in mice prone to autoimmune diabetes and whether the nitric oxide (NO)-cyclic GMP axis is involved. Aortic rings suspended in organ chambers and precontracted with phenylephrine were exposed to cumulative concentrations of acetylcholine. To investigate the role of NO, some experiments were performed in the presence of either 1400W ( N-(3-aminomethyl)benzyl-acetamidine hydrochloride), a selective inhibitor of the iNOS-isoform, l-NAME ( N G-nitro- l-arginine methyl ester hydrochloride), an inhibitor of all three NOS-isoforms, or ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), a selective inhibitor of guanylate cyclase. Moreover, contractility to phenylephrine, big endothelin-1, and endothelin-1 was assessed and histological analysis and iNOS immunohistochemistry were performed. Endothelium-dependent relaxation was reduced in prediabetic NOD mice (78 ± 4 vs. 88 ± 2%, respectively, P < 0.05 vs. control) despite normal plasma glucose levels (n.s. vs. control). Preincubation with 1400W further attenuated responses in prediabetic ( P < 0.05 vs. untreated) but not in diabetic or in control mice. In contrast, basal NO bioactivity remained unaffected until the onset of diabetes in NOD mice. Contractile responses to big endothelin-1 and endothelin-1 were reduced in prediabetic animals ( P < 0.05 vs. control), whereas in diabetic mice only responses to big endothelin-1 were decreased ( P < 0.05 vs. control). These data demonstrate that endothelium-dependent and -independent vascular function in NOD mice is abnormal already in prediabetes in the absence of structural injury. Early proinflammatory activation due to iNOS in diabetes-prone NOD mice appears to be one of the mechanisms contributing to impaired vasoreactivity.

Tu-P7:95 Glycosphingolipids as a early markers of cardiovascular diseases in diabetes mellitus

Type 1 diabetes is an immuno-inflammatory condition which increases the risk of cardiovascular disease, particularly in young adults. This study investigated whether vascular function is altered in mice prone to autoimmune diabetes and whether the nitric oxide (NO)-cyclic GMP axis is involved. Aortic rings suspended in organ chambers and precontracted with phenylephrine were exposed to cumulative concentrations of acetylcholine. To investigate the role of NO, some experiments were performed in the presence of either 1400W (N-(3-aminomethyl)benzyl-acetamidine hydrochloride), a selective inhibitor of the iNOS-isoform, l-NAME (NG-nitro-l-arginine methyl ester hydrochloride), an inhibitor of all three NOS-isoforms, or ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), a selective inhibitor of guanylate cyclase. Moreover, contractility to phenylephrine, big endothelin-1, and endothelin-1 was assessed and histological analysis and iNOS immunohistochemistry were performed. Endothelium-dependent relaxation was reduced in prediabetic NOD mice (78 ± 4 vs. 88 ± 2%, respectively, P < 0.05 vs. control) despite normal plasma glucose levels (n.s. vs. control). Preincubation with 1400W further attenuated responses in prediabetic (P < 0.05 vs. untreated) but not in diabetic or in control mice. In contrast, basal NO bioactivity remained unaffected until the onset of diabetes in NOD mice. Contractile responses to big endothelin-1 and endothelin-1 were reduced in prediabetic animals (P < 0.05 vs. control), whereas in diabetic mice only responses to big endothelin-1 were decreased (P < 0.05 vs. control). These data demonstrate that endothelium-dependent and -independent vascular function in NOD mice is abnormal already in prediabetes in the absence of structural injury. Early proinflammatory activation due to iNOS in diabetes-prone NOD mice appears to be one of the mechanisms contributing to impaired vasoreactivity.

Vasopeptidase Inhibition Normalizes Blood Pressure and Restores Endothelial Function in Renovascular Hypertension

Background/Aims: Vasopeptidase inhibitors by definition inhibit both angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP), therefore they may exceed the effect of ACE inhibitors in the treatment of hypertension. The present study investigated the effect of the vasopeptidase inhibitor AVE7688 in comparison to the ACE inhibitor ramipril on systolic blood pressure (SBP) and endothelial function in renovascular hypertension. Methods: Wistar-Kyoto rats with renovascular hypertension (two-kidney one-clamp-model) were randomized 2 weeks after unilateral clamping of the right renal artery for 3 weeks’ oral treatment with either AVE7688 (30 mg/kg/day), ramipril (1 mg/kg/day) or placebo. SBP was measured by the tail-cuff method and endothelium-dependent and -independent vascular function was assessed in isolated preconstricted (norepinephrine 10^–7 mol/l) aortic rings as relaxation to acetylcholine (10^–10–10^–4 mol/l) and sodium nitroprusside (10^–10–10^–4 mol/l), respectively. Results: Two weeks after clamping, SBP was significantly elevated (196 ± 16 vs. 145 ± 8 mm Hg for sham-operated rats; p < 0.01) and further increased in placebo-treated animals to 208 ± 19 mm Hg. Treatment with AVE7688 and ramipril had a similar blood pressure-lowering effect (119 ± 8 and 124 ± 10 mm Hg, respectively; p < 0.01 vs. placebo). Maximum endothelium-dependent relaxation was reduced in hypertensive rats (72 ± 6 vs. 99 ± 7% in control rats; p < 0.05). Endothelium-dependent relaxation was restored by AVE7688 (101 ± 6%) and ramipril (94 ± 8%), respectively, whereas endothelium-independent relaxation was comparable in all groups. Conclusion: In renovascular hypertension the vasopeptidase inhibitor AVE7688 exhibited similar blood pressure-lowering and endothelial protective properties as compared to the ACE inhibitor ramipril. Therefore, in high renin models of hypertension, vasopeptidase inhibition may be considered an alternative treatment option to ACE inhibition.

Predictors of Endothelial Dysfunction in Young Women with Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) may be at increased risk for cardiovascular disease. Endothelial dysfunction is an early marker of atherosclerosis. The objectives of this study were to 1) compare endothelial function in young women with PCOS and regularly menstruating control women, and 2) to identify the determinants of endothelial function and investigate its relationship with body mass index in women with PCOS. This was a cross-sectional study. This study was conducted at a tertiary cardiovascular research center. Sixty-two young women with PCOS (mean age, 22.7 yr) and 17 control women, matched as a group for age and body mass index, were studied. Twenty-three women with PCOS were lean, 21 were overweight, and 18 were obese. Endothelium-dependent and -independent vascular function was assessed by measuring flow-mediated dilation (FMD) and nitrate-mediated dilation in the brachial artery (diameter change during hand hyperemia and after sublingual glyceryl trinitrate administration, respectively). FMD and nitrate-mediated dilation were significantly lower in PCOS than in control women (reduced by approximately 50 and 25%, respectively; both P < 0.0005). Insulin resistance, total testosterone, and total cholesterol were independent predictors of FMD, accounting for 21, 10, and 9% of the variance, respectively (P < 0.005 for all). A trend of deterioration in FMD from lean to overweight and obese PCOS women was observed, but differences among groups were not statistically significant. Women with PCOS have significant endothelial dysfunction at an early age (i.e. early 20s), and largely independent of obesity. This suggests that women with PCOS are at increased risk for early onset cardiovascular disease and may gain particular benefit from measures to improve endothelial function.

Increase in nitric oxide bioavailability improves endothelial function in endothelin-1 transgenic mice.

Endothelin-1 (ET-1) has been described as a very potent vasoconstrictor. Nevertheless, transgenic mice overexpressing ET-1 have been shown to exhibit normal blood pressure. We thus hypothesized that vascular ET-1 effects may be antagonized by increased activity of other regulatory systems, such as the increase in bioavailability of the endothelial counterpart of ET-1, nitric oxide (NO). Endothelium-dependent and -independent vascular function was assessed as relaxation/contraction of isolated preconstricted aortic rings to acetylcholine (10(-10)-10(-4) mol/l), sodium nitroprusside (10(-10)-10(-4) mol/l), ET-1 (10(-10)-10(-7) mol/l) and big ET-1 (10(-10)-10(-7) mol/l), respectively, in ET-1 transgenic mice and corresponding controls. To unmask the impact of the NO system, we furthermore analysed vessel rings incubated in vitro with the NO-synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME, 10(-4) mol/l). Maximum endothelium-dependent relaxation was enhanced in ET-1 transgenic mice (93+/-3% vs 84+/-4% for wild-type littermates; P<0.05) and was inhibited by preincubation with L-NAME in both ET-transgenic mice and wild-type littermates (11+/-5% vs 9+/-4% maximum relaxation, respectively). Endothelium-independent relaxation was similar among all groups. Maximum vascular contraction to ET-1 and big ET-1 was reduced in ET-1 transgenic mice (P<0.05 vs wild-type littermates). Preincubation with L-NAME reduced this difference, indicating the involvement of augmented NO availability. Correspondingly, urinary nitrate/nitrite excretion was significantly elevated in ET-1 transgenic mice. These data suggest that in transgenic mice overexpressing ET-1, increased NO bioavailability counteracts the contractile potency of elevated ET-1 levels and leads to an improvement of endothelium-dependent relaxation. Thus, in the presence of an activated ET system, up-regulation of NO production may be capable of maintaining vascular tone in a normal range and therefore may prevent the development of hypertension.

Endothelin in the mechanism of endothelial injury and neutrophil adhesion in the post-ischemic guinea-pig heart

This study addressed the hypothesis that endothelin promotes neutrophil accumulation in ischemic/reperfused myocardium, not only via its direct effect on neutrophils, but also because it mediates post-ischemic endothelial injury. Langendorff-perfused guinea-pig hearts were subjected to 30 min ischemia/35 min reperfusion, and infusion of neutrophils between 15 and 25 min of reperfusion. The infusion of the endothelin ET A/ET B receptor antagonist, tezosentan, the endothelin ET A receptor antagonist, BQ 123 [cyclo(- d-Trp- d-Asp-Pro- d-Val-Leu-], and superoxide dismutase was terminated at reperfusion, 5 min before the start of the neutrophil infusion, to avoid the contact of the drugs with neutrophils. Coronary flow responses to acetylcholine and nitroprusside were used as measures of endothelium-dependent and -independent vascular function, respectively. Neutrophil adhesion and endothelium glycocalyx ultrastructure were assessed in histological preparations. Ischemia/reperfusion resulted in a 54%-impaired acetylcholine response, endothelium glycocalyx disruption, and enhanced neutrophil adhesion (21.6% of microvessels contained neutrophils vs. 2.6% in sham group), the latter prevented by a selectin blocker, sulfatide, 20 μg/ml. These alterations were completely prevented by 0.5 and 5 nM, but not 0.05 nM, tezosentan, and were greatly attenuated by BQ 123, 1 and 10 nM. The glycocalyx-protective effect of these interventions preceded their effect on neutrophil adhesion. Superoxide dismutase, 150 IU/ml, reported before by us to protect post-ischemic endothelium glycocalyx, here prevented the post-ischemic endothelial dysfunction and neutrophil adhesion. The data imply that neutrophil adhesion in ischemic/reperfused guinea-pig heart is a selectin-dependent process, secondary to mostly endothelin ET A receptor- and free radical-mediated functional and/or structural changes in the coronary endothelium. Thus, endothelin ET A/ET B as well as ET A receptor antagonists may be useful in attenuation of the inflammatory response in ischemic/reperfused heart. The antagonists may be effective because of their direct effect on neutrophils, as demonstrated by others, and because they provide endothelial protection, as demonstrated here.

Post-prandial lipaemia and endothelial function among healthy men.

There is evidence that elevated post-prandial lipoproteins adversely affect progression and outcome of cardiovascular disease. Traditional risk factors are associated with impaired endothelium-mediated vasodilatation. However, studies regarding the relationship between post-prandial lipaemia and endothelial function are divergent. Twelve healthy non-smokers were included in this study. Before and after intake of a lipid cocktail rich in dairy fat, we tested endothelial-dependent (acetylcholine 0.8-160 mg/min per 100 ml forearm tissue) and -independent (sodium nitroprussid 0.6 microgram/min) vascular function in the forearm vascular bed with plethysmography. Moreover, we tested the effect of 1-NMMA, a competitive inhibitor of the NO synthetase, on base-line flow. Extent of post-prandial lipaemia was assessed with the increases in triglycerides and retinyl-palmitate, a marker for intestinally derived lipoproteins. Baseline flow was higher after the test meal than during fasting (preprandial 6.5 +/- 0.5 ml/min* 100 ml tissue, post-prandial 8.0 +/- 0.5, p = 0.03), but similar after 1-NMMA (p = 0.85). Before and after intake of the test meal, there was no significant difference in acetylcholine-induced endothelium-dependent vasodilatation (repeated measurement ANOVA, p = 0.22). At the highest acetylcholine dose, forearm flow was very similar (fasting 18.4 +/- 1.9, post-prandial 17.9 +/- 1.9, p = 0.75). At maximum acetylcholine dose, there was a weak inverse but non-significant correlation between forearm flow and post-prandial triglyceridaemia (r = -0.38, p = 0.23) and intestinally derived lipoproteins (chylomicrons r = -0.29, p = 0.35, chylomicron remnants r = -0.15, p = 0.63). However, at the lowest acetylcholine dose there was a suggestion for a positive correlation between change in flow and post-prandial lipaemia (triglyceridaemia, r = 0.53, p = 0.07; chylomicrons, r = 0.41, p = 0.18 and remnants, r = 0.51, p = 0.09). Endothelium-independent vasodilatation in response to sodium nitroprusside did not significantly change (p = 0.23). Our results suggest that among healthy men post-prandial lipaemia is not associated with a notable impairment of endothelium-mediated vascular function in forearm resistance vessels.

Post-prandial lipaemia and endothelial function among healthy men.

There is evidence that elevated post-prandial lipoproteins adversely affect progression and outcome of cardiovascular disease. Traditional risk factors are associated with impaired endothelium-mediated vasodilatation. However, studies regarding the relationship between post-prandial lipaemia and endothelial function are divergent. Twelve healthy non-smokers were included in this study. Before and after intake of a lipid cocktail rich in dairy fat, we tested endothelial-dependent (acetylcholine 0.8-160 mg/min per 100 ml forearm tissue) and -independent (sodium nitroprussid 0.6 microgram/min) vascular function in the forearm vascular bed with plethysmography. Moreover, we tested the effect of 1-NMMA, a competitive inhibitor of the NO synthetase, on base-line flow. Extent of post-prandial lipaemia was assessed with the increases in triglycerides and retinyl-palmitate, a marker for intestinally derived lipoproteins. Baseline flow was higher after the test meal than during fasting (preprandial 6.5 +/- 0.5 ml/min* 100 ml tissue, post-prandial 8.0 +/- 0.5, p = 0.03), but similar after 1-NMMA (p = 0.85). Before and after intake of the test meal, there was no significant difference in acetylcholine-induced endothelium-dependent vasodilatation (repeated measurement ANOVA, p = 0.22). At the highest acetylcholine dose, forearm flow was very similar (fasting 18.4 +/- 1.9, post-prandial 17.9 +/- 1.9, p = 0.75). At maximum acetylcholine dose, there was a weak inverse but non-significant correlation between forearm flow and post-prandial triglyceridaemia (r = -0.38, p = 0.23) and intestinally derived lipoproteins (chylomicrons r = -0.29, p = 0.35, chylomicron remnants r = -0.15, p = 0.63). However, at the lowest acetylcholine dose there was a suggestion for a positive correlation between change in flow and post-prandial lipaemia (triglyceridaemia, r = 0.53, p = 0.07; chylomicrons, r = 0.41, p = 0.18 and remnants, r = 0.51, p = 0.09). Endothelium-independent vasodilatation in response to sodium nitroprusside did not significantly change (p = 0.23). Our results suggest that among healthy men post-prandial lipaemia is not associated with a notable impairment of endothelium-mediated vascular function in forearm resistance vessels.

Effect of aerobic and resistance exercise training on vascular function in heart failure.

Exercise training of a muscle group improves local vascular function in subjects with chronic heart failure (CHF). We studied forearm resistance vessel function in 12 patients with CHF in response to an 8-wk exercise program, which specifically excluded forearm exercise, using a crossover design. Forearm blood flow (FBF) was measured using strain-gauge plethysmography. Responses to three dose levels of intra-arterial acetylcholine were significantly augmented after exercise training when analyzed in terms of absolute flows (7.0 +/- 1.8 to 10.9 +/- 2.1 ml x 100 ml(-1) x min(-1) for the highest dose, P < 0.05 by ANOVA), forearm vascular resistance (21.5 +/- 5.0 to 15.3 +/- 3.9 ml x 100 ml forearm(-1) x min(-1), P < 0.01), or FBF ratios (P < 0.01, ANOVA). FBF ratio responses to sodium nitroprusside were also significantly increased after training (P < 0.05, ANOVA). Reactive hyperemic flow significantly increased in both upper limbs after training (27.9 +/- 2.7 to 33.5 +/- 3.1 ml x 100 ml(-1) x min(-1), infused limb; P < 0.05 by paired t-test). Exercise training improves endothelium-dependent and -independent vascular function and peak vasodilator capacity in patients with CHF. These effects on the vasculature are generalized, as they were evident in a vascular bed not directly involved in the exercise stimulus.