Evaluation of mild hyperhomocysteinemia during the development of atherosclerosis in apolipoprotein E-deficient and normal mice

We focused on the effect of mild hyperhomocysteinemia (HHcy) on the development of atherosclerosis, using apolipoprotein E-deficient (apoE(-/-)) and normal mice. Mice received diets enriched in methionine with low or high levels of folate, B(12) and B(6) (diets B and C, respectively), and diet only with low levels of folate, B(12) and B(6) (diets D), to induce mild HHcy. Normal mice fed on diets B, C and D presented mild HHcy, but they did not develop atherosclerotic lesions after 24 weeks of diet. In addition, increased endoplasmic reticulum stress was present in normal mice fed on diet B, compared to others groups. ApoE(-/-) mice fed on diet B for 20 weeks presented the greatest atherosclerotic lesion area at the aortic sinus than other groups. These results suggest that the methionine may have a toxic effect on endothelium, and the B-vitamins addition on diet may have a protective effect in the long term, despite the increase on homocysteine levels. Mild HHcy accelerated the development of atherosclerosis in apoE(-/-) mice, and supplementation with B-vitamins is important for prevention of vascular disease, principally in the long term. (C) 2010 Elsevier Inc. All rights reserved.

Asymmetric dimethylarginine endogenous inhibition of nitric oxide synthase causes differential vasculature effects

Background: Asymmetric dimethylarginine (ADMA), produced during protein metabolism, is an endogenous inhibitor of nitric oxide synthase, but little is known about its direct vasoactive properties in different arterial beds. Material/Methods: Segments of canine coronary, renal, and femoral arteries were pretreated with increasing concentrations of ADMA, and endothelial function was evaluated in organ chambers. Results: In precontracted canine coronary arteries, the highest concentrations of ADMA inhibited endothelium-dependent relaxation mediated by acetylcholine (n=7), but no concentration of ADMA inhibited receptor-independent relaxation mediated by calcium ionophore (n=7) (P<.001). The effect of ADMA on acetylcholine-mediated relaxation was shown to be competitive inhibition of the nitric oxide synthase pathway, because the addition of L-arginine (10(-3) M), but not D-arginine (101 M), reversed the effect produced by 10(-5) M ADMA. Further, ADMA did not alter endothelium-independent relaxation mediated by sodium nitroprusside (10(-9) to 10(-6) M; n=7). Femoral arteries (n=7) and renal arteries (n=7) were more sensitive to ADMA than were coronary arteries, and they demonstrated significant ADMA inhibition to receptor dependent relaxation induced by acetylcholine (P=.03 and P=.01, respectively) and to receptor-independent relaxation induced by calcium ionophore (P=.02 and P=.01, respectively). Conclusions: Endothelium-dependent relaxation mediated by ADMA is more marked in femoral and renal arteries than in coronary arteries. The response in coronary arteries may be overall protective. Considering these different effects in various artery types, the role of ADMA as a confiable and specific cardiovascular risk factor is questioned.

Antihypertensive effects exerted by enalapril in mild to moderate hypertension are not associated with changes in the circulating levels of nitric oxide-related markers

The antihypertensive effects of angiotensin-converting enzyme inhibitors (ACEi) are explained, at least in part, by enhanced bradykinin-dependent nitric oxide (NO) formation and decreased angiotensin II-induced oxidative stress and vasoconstriction. We examined for the first time whether treatment with enalapril increases the plasma levels of markers of NO formation and decreases oxidative stress in mild to moderate hypertensive patients. Eighteen untreated hypertensive patients were treated with enalapril 10 mg/day (n = 10) or 20 mg/day (n = 8) for 60 days. Eighteen normotensive healthy controls were followed for the same period. Venous blood samples were collected at baseline and after 30/60 days of treatment with enalapril. Plasma NOx (nitrites + nitrates) concentrations were determined by using the Griess reaction. Plasma nitrite and whole blood nitrite concentrations were determined by using an ozone-based chemiluminescence assay. Plasma thiobarbituric acid-reactive species (TBARS) and 8-isoprostane concentrations were determined by a fluorimetric method and by ELISA, respectively. Treatment with enalapril decreased blood pressure in hypertensive patients. However, we found no significant changes in plasma NOx, nitrite, whole blood nitrite, and in the levels of markers of oxidative stress in both normotensive controls and hypertensive patients treated with enalapril. Our data show that enalapril 10-20 mg/day does not affect the concentrations of relevant markers of NO formation or markers of oxidative stress in mild to moderately hypertensive subjects, despite satisfactory blood pressure control. Our findings do not rule out the possibility that ACEi may produce such effects in more severely hypertensive patients treated with higher doses of ACEi.

PULSATILITY INDEX CHANGE OF BRACHIAL ARTERY SHOWS BETTER REPRODUCIBILITY THAN FLOW-MEDIATED VASODILATION

We aim to evaluate intra- and interobserver reproducibility of brachial artery flow-mediated dilation (FMD) and of pulsatility index change (PI-C) 1 min after a 5-min forearm compression in pregnant women. Flow-mediated dilation and PI-C were assessed in 31 healthy pregnant women in 3 consecutive days, by two observers. A broader range of response to the stimulus was observed for PI-C (-58.99%-86.71%) than FMD (2.38%-27.01%). The intraclass correlation coefficients were higher for PI-C than for FMD (intra = 0.90 vs. 0.69, p = 0.047; inter = 0.94 vs. 0.61, p = 0.007). Therefore, PI-C measurements were more reliable than FMD. However, studies comprising of subjects with cardiovascular risk factors relating FMD and PI-C become necessary to validate this method for the study of endothelial dysfunction. (E-mail: wpmartins@gmail.com) (C) 2010 World Federation for Ultrasound in Medicine & Biology.

Effects of the levonorgestrel-releasing intrauterine system on cardiovascular risk markers in patients with endometriosis: a comparative study with the GnRH analogue

Background: The study was conducted to evaluate the cardiovascular risk markers associated with endometriosis and the influence of the levonorgestrel intrauterine system (LNG-TUS) compared with the GnRH analogue (GnRHa) leuprolide acetate on these risk markers after 6 months of treatment. Study Design: This was a randomized, prospective, open clinical Study, with 44 patients with laparoscopically and histologically confirmed endometriosis. Patients were randomized into two groups: the LNG-IUS group, composed of 22 patients who underwent LNG-IUS insertion., and the GnRHa group, composed of 22 patients who received a monthly GnRHa injection for 6 months. Body mass index systolic and diastolic arterial blood pressure; heart rate; and laboratory cardiovascular risk markers such as interlelikin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), C-reactive protein (CRP), homocysteine (HMC), lipid profile, total leukocytes and vascular cell adhesion molecule (VCAM) were measured before and 6 months after treatment. Results: After 6 months of treatment, a significant reduction in pain score occurred in both groups with no significant difference in improvement between the two medications evaluated. In the LNG-IUS group, from pretreatment to posttreatment period, there was a significant reduction in the levels (mean +/- SD) of VCAM (92.8 +/- 4.2 to 91.2 +/- 2.7 ng/mL, p=.04), CRP (0.38 +/- 0.30 to 0.28 +/- 0.21 mg/dL, p=.03), total cholesterol (247.0 +/- 85.0 to 180.0 +/- 31.0 mg/dL, p=.0002), triglycerides (118.0 +/- 76.0 to 86.5 +/- 41.5 mg/dL, p=.003), low-density lipoprotein cholesterol (160.5 +/- 66.0 to 114.5 +/- 25.5 mg/dL, p=.0005) and high-density lipoprotein cholesterol (63.0 +/- 20.5 to 48.5 +/- 10.5 mg/dL, p=.002). The GnRHa group showed an increase in HMC levels (11.5 +/- 2.9 to 13.0 +/- 2.7 mu mol/L, p=.04) and a reduction in IL-6 levels (4.3 +/- 3.9 to 2.3 +/- 0.8 pg/mL, p=.005), VCAM (94.0 +/- 3.8 to 92.0 +/- 1.6 ng/mL, p=.03) and total leukocytes (7330 +/- 2554 to 6350 +/- 1778, p=.01). In the GnRH group, the remaining variables, including lipid profile, did not show any statistical difference. Conclusions: This study shows that some cardiovascular risk markers are influenced by both GnRHa and the LNG-TUS, but the latter had a greater positive impact on the lipid profile, which could lead to a favorable effect during long-term treatment. (C) 2010 Elsevier Inc. All rights reserved.

Increased arterial stiffness in nonobese women with polycystic ovary syndrome (PCOS) without comorbidities: one more characteristic inherent to the syndrome?

Background Polycystic ovary syndrome (PCOS) is associated with adverse metabolic effects. Some cardiovascular disease (CVD) risk markers are increased in women with PCOS. However, early markers of atherosclerosis are also associated with obesity and insulin resistance, which are related to PCOS. These markers may result either directly from PCOS or indirectly as a consequence of the comorbidities associated with the syndrome. Context To assess the presence of early CVD markers in young, nonobese women with PCOS. Patients Forty women with PCOS and 50 healthy women with regular menstrual cycles, matched for age and body mass index (BMI). Measurements The following CVD markers were assessed by ultrasonography: common carotid artery (CCA) stiffness index (beta), distensibility and intima-media thickness (IMT), and brachial artery flow-mediated dilatation (FMD). Inflammatory markers, including interleukin (IL)-6, tumour necrosis factor (TNF)-alpha, homocysteine, C-reactive protein (CRP), glycaemia, lipid profile and insulin, were also assessed. Results CCA beta was higher in PCOS than in control women (3 center dot 72 +/- 0 center dot 96 vs. 3 center dot 36 +/- 0 center dot 96, P = 0 center dot 04) and CCA distensibility was lower (0 center dot 31 +/- 0 center dot 08 vs. 0 center dot 35 +/- 0 center dot 09 mmHg(-1), P = 0 center dot 02). Waist circumference, total testosterone and the Free Androgen Index (FAI) were higher in PCOS patients than in controls (78 center dot 2 +/- 10 center dot 0 vs. 71 center dot 5 +/- 7 center dot 2 cm, P = 0 center dot 001; 88 center dot 1 +/- 32 center dot 4 vs. 57 center dot 1 +/- 21 center dot 2 ng/dl, P < 0 center dot 01; 12 center dot 7 +/- 15 center dot 7%vs. 4 center dot 7 +/- 2 center dot 3%, P < 0 center dot 01, respectively), while SHBG was reduced (37 center dot 9 +/- 19 center dot 1 vs. 47 center dot 8 +/- 18 center dot 3 nmol/l, P = 0 center dot 01). The remaining variables did not differ between the groups. Conclusions Young women with PCOS exhibit changes in vascular elasticity even in the absence of classical risk factors for CVD, such as hypertension and obesity.

Brachial artery pulsatility index change 1 minute after 5-minute forearm compression - Comparison with flow-mediated dilatation

Objective. Endothelial impairment evaluation by sonographic measurement of flow-mediated dilatation (FMD) has become broadly used. However, this method has 2 main caveats: the dilatation depends on the baseline arterial diameter, and a high precision level is required. Vasodilatation leads to an amplified fall in impedance. We hypothesized that assessment of the pulsatility index change (PI-C) 1 minute after 5-minute forearm compression might evaluate that fall in impedance. The aim of this study was to compare the PI-C with FMD. Methods. Flow-mediated dilatation and the PI-C were assessed in 51 healthy women aged between 35.1 and 67.1 years. We correlated both FMD and the PI-C with age, body mass index, waist circumference, cholesterol level, high-density lipoprotein level, glucose level, systolic and diastolic blood pressure, pulse pressure, brachial artery diameter, simplified Framingham score, intima-media thickness, and carotid stiffness index. Intraclass correlation coefficients between 2 FMD and PI-C measurements were also examined. Results. Only FMD correlated with baseline brachial diameter (r=-0.53). The PI-C had a high correlation with age, body mass index, waist circumference, cholesterol level, systolic blood pressure, pulse pressure, simplified Framingham score, and intima-media thickness. The correlation between FMD and the PI-C was high (r=-0.66). The PI-C had a higher intraclass correlation coefficient (0.991) than FMD (0.836) but not brachial artery diameter (0.989). Conclusions. The PI-C had a large correlation with various markers of cardiovascular risk. Additionally, PI-C measurement does not require offline analysis, extra software, or electrocardiography We think that the PI-C could be considered a marker of endothelial function. However, more studies are required before further conclusions.

Influence of pregnancy and smoking on brachial artery flow-mediated dilation values and time until maximum response

To evaluate the effect of pregnancy and smoking on endothelial function using brachial artery flow-mediated dilation (FMD) and to determine the time necessary until the occurrence of maximum brachial artery dilation after stimulus. This study was an observational study evaluating 133 women, who were grouped as follows: non-smoking pregnant women (N = 47), smoking pregnant women (N = 33), non-smoking women (N = 34), and smoking pregnant women (N = 19). The diameter of the brachial artery was measured at baseline and at 30, 60, 90 and 120 s after stimulus. The relative change of brachial artery was determined for each of these four moments. FMD measured at 60 s after stimulus was compared between the groups. The maximum FMD was observed at 60 s after cuff release in all groups. FMD was greater among non-smoking pregnant women compared to smoking pregnant women (11.50 +/- A 5.77 vs. 8.74 +/- A 4.83; p = 0.03) and also between non-smoking non-pregnant women compared to smoking non-pregnant women (10.52 +/- A 4.76 vs. 7.21 +/- A 5.57; p = 0.03). Maximum FMD was observed approximately 60 s after stimulus in all groups regardless of smoking and pregnancy status. The smoking habit seems to lead to endothelial dysfunction both in pregnant and non-pregnant women, as demonstrated by the lower FMD in smokers.

Chronic Ethanol Consumption Induces Cavernosal Smooth Muscle Dysfunction in Rats

OBJECTIVES To investigate the effects of chronic ethanol consumption on nitric oxide (NO)-mediated relaxation in rat cavernosal smooth muscle (CSM). METHODS Male wistar rats were divided into 2 groups: control and ethanol. CSM obtained from both groups were mounted in organ chambers for measurement of isometric tension. Contraction of the strips was induced by electrical field stimulation (EFS, 1-32 Hertz) and phenylephrine. We also evaluated the effect of ethanol consumption on the relaxation induced by acetylcholine (0.01-1000 mu mol L(-1)), sodium nitroprusside (SNP, 0.01-1000 mu mol L(-1)), or EFS (1-32 Hz) in strips precontracted with phenylephrine (10 mu mol L(-1)). Blood ethanol, serum testosterone levels, and basal nitrate generation were determined. Immunoexpression of endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) was also accessed. RESULTS Ethanol intake for 4 weeks significantly increased noradrenergic nerve-mediated contractions of CSM in response to EFS. The endothelium-dependent relaxation induced by acetylcholine decreased after the ethanol treatment. Ethanol consumption decreased serum testosterone levels but did not affect the nitrate levels on rat CSM. The mRNA and protein levels for eNOS and iNOS receptors were increased in CSM from ethanol-treated rats. CONCLUSIONS Ethanol consumption reduces endothelium-dependent relaxation induced by acetylcholine, but does not affect SNP or EFS-induced relaxation, suggesting that ethanol disrupts the endothelial function. Despite the overexpression of eNOS and iNOS in ethanol-treated rats, the impaired relaxation induced by acetylcholine may suggest that chronic ethanol consumption induces endothelial dysfunction. UROLOGY 74: 1250-1256, 2009. (C) 2009 Published by Elsevier Inc.

Quercetin restores plasma nitrite and nitroso species levels in renovascular hypertension

Quercetin has antioxidants properties which may increase nitric oxide (NO) bioavailability. However, the effects of quercetin on NO status have been poorly studied. We evaluated whether quercetin improves the plasma levels of NO metabolites in two-kidney one-clip (2K1C) hypertensive rats and assessed its effect on endothelial function. Sham-operated and 2K1C rats were treated with quercetin (10 mg(-1) kg(-1) day(-1) by gavage) or vehicle for 3 weeks. Systolic blood pressure (SBP) was monitored weekly. Vascular responses to acetylcholine (Ach) and sodium nitroprusside (SNP) were assessed in hindquarter vascular bed. Plasma nitrate levels were assessed by Griess reagent and plasma nitrite and nitroso species (S, N-nitroso species) were assessed by ozone- based chemiluminescence. Aortic NADPH oxidase activity and superoxide production were evaluated. While quercetin had no effects in control normotensive rats (P > 0.05), it significantly reduced SBP in 2K1C rats (P < 0.05). At the end of treatment, plasma nitrate levels were similar in all experimental groups (P > 0.05). However, plasma nitrite and the nitroso species levels were significantly lower in 2K1C rats when compared with controls (P < 0.05). Quercetin treatment restored plasma nitrite and nitroso species levels to those found in the sham-vehicle group (P < 0.05). While quercetin treatment induced no significant changes in responses to SNP (P > 0.05), it restored the vascular responses to Ach. Quercetin significantly attenuated 2K1C-hypertension-induced increases in NADPH oxidase activity and vascular superoxide production (P < 0.05). These results suggest that the antihypertensive effects of quercetin were associated with increased NO formation and improved endothelial function, which probably result from its antioxidant effects.

Vascular dysfunction and heart failure: Epiphenomenon or etiologic agent?

Endothelial function plays a key role in the local regulation of vascular tone. Alterations in endothelial function may result in impaired release of endothelium-derived relaxing factors or increased release of endothelium-derived contracting factors. Heart failure may impair endothelial function by means of reduced synthesis and release of nitric oxide (NO) or by increased degradation of NO and increased production of endothelin-1. Endothelial dysfunction may worsen heart function by means of peripheral effects, causing increased afterload and central effects such as myocardial ischemia and inducible nitric oxide synthase (iNOS)-induced detrimental effects. Evidence from clinical studies has suggested that there is a correlation between decreased endothelial function and increasing severity of congestive heart failure (CHF). Treatments that improve heart function may also improve endothelial dysfunction. The relationship between endothelial dysfunction and heart failure may be masked by the stage of endothelial dysfunction, the location of vessels being tested, and the state of endothelial-dependent vasodilatation response.

Mechanisms of exercise training in patients with heart failure

Background The reduction of exercise capacity because of fatigue and dyspnea in patients with heart failure can be improved with exercise training. We sought to examine the mechanisms of exercise training, as an adjunctive treatment strategy for patients with heart failure. Methods a reviewed the published data on the possible mechanisms of effect of exercise training in heart failure. Results Symptoms of heart failure may be explained on the basis of abnormal skeletal muscle perfusion and structure and endothelial function. Exercise training has been shown to engender changes in muscle structure and biochemistry and vascular function, although effects on cardiac function have not been detected uniformly and may require longer training periods. Conclusions A suitable, long-term program of exercise training may reverse unfavorable interactions among the heart, vessels, and skeletal muscles. These improvements may be preserved with an ongoing maintenance program.

Acute lead-induced vasoconstriction in the vascular beds of isolated perfused rat tails is endothelium-dependent

Chronic lead exposure induces hypertension in humans and animals, affecting endothelial function. However, studies concerning acute cardiovascular effects are lacking. We investigated the effects of acute administration of a high concentration of lead acetate (100 µΜ) on the pressor response to phenylephrine (PHE) in the tail vascular bed of male Wistar rats. Animals were anesthetized with sodium pentobarbital and heparinized. The tail artery was dissected and cannulated for drug infusion and mean perfusion pressure measurements. Endothelium and vascular smooth muscle relaxation were tested with acetylcholine (5 µg/100 µL) and sodium nitroprusside (0.1 µg/100 µL), respectively, in arteries precontracted with 0.1 µM PHE. Concentration-response curves to PHE (0.001-300 µg/100 µL) were constructed before and after perfusion for 1 h with 100 µΜ lead acetate. In the presence of endothelium (E+), lead acetate increased maximal response (Emax) (control: 364.4 ± 36, Pb2+: 480.0 ± 27 mmHg; P < 0.05) and the sensitivity (pD2; control: 1.98 ± 0.07, 2.38 ± 0.14 log mM) to PHE. In the absence of endothelium (E-) lead had no effect but increased baseline perfusion pressure (E+: 79.5 ± 2.4, E-: 118 ± 2.2 mmHg; P < 0.05). To investigate the underlying mechanisms, this protocol was repeated after treatment with 100 µM L-NAME, 10 µM indomethacin and 1 µM tempol in the presence of lead. Lead actions on Emax and pD2 were abolished in the presence of indomethacin, and partially abolished with L-NAME and tempol. Results suggest that acute lead administration affects the endothelium, releasing cyclooxygenase-derived vasoconstrictors and involving reactive oxygen species.

Avaliação do stress oxidativo na disfunção erétil

As sequelas fisiopatológicas do stress oxidativo são difíceis de quantificar. Apesar dos obstáculos, a relevância médica do stress oxidativo tem vindo a ser cada vez mais reconhecida, sendo hoje em dia encarado como um componente chave de virtualmente todas as doenças. A disfunção erétil (DE) surge neste contexto como uma espécie de barómetro da função endotelial e do dano oxidativo. A quantificação de biomarcadores de stress oxidativo poderá apresentar um enorme impacto na avaliação de pacientes com DE. O rácio glutationa reduzida/oxidada (GSH/GSSG) e a nitrotirosina (3-NT) têm vindo a demonstrar relevância clínica. A consideração de polimorfismos genéticos constitui ainda uma abordagem promissora na avaliação destas relações no futuro. Um método altamente sensível de cromatografia líquida de alta performance (HPLC) foi desenvolvido para a determinação de 3-NT em plasma humano. As concentrações de 3-NT medidos em indivíduos com DE foram 6,6±2,1μM (média±S.D., n = 46). A medição da concentração plasmática de 3-NT poderá revelar-se útil como marcador de dano oxidativo dependente do óxido nítrico (NO). O nível de stress oxidativo pode também ser quantificado através da medição do decréscimo do rácio GSH/GSSG, que tem mostrado alterações numa miríade de patologias, como a DE e a diabetes mellitus. O método proposto para a quantificação do rácio GSH/GSSG em HPLC apresenta a vantagem de avaliação concomitante dos dois parâmetros em apenas uma corrida. O valor do rácio GSH/GSSG obtido a partir de sangue de indivíduos com DE foi 11,9±9,8 (média±S.D., n = 49). Os resultados estatísticos revelaram diferenças significativas (p<0,001) entre ambos a concentração plasmática de 3-NT e o rácio GSH/GSSG de sangue de indivíduos com DE e as respetivas medições em indivíduos saudáveis. Observaram-se ainda diferenças estatisticamente significativas (p≈0,027) entre o rácio GSH/GSSG do sangue de pacientes apenas com diagnóstico de DE e a medição respetiva em indivíduos com DE e comorbilidades cardiovasculares. Estes resultados enfatizam o papel do dano oxidativo na biopatologia da DE, elucidado com o auxílio destas duas metodologias, que poderão ter um amplo campo de aplicação no futuro, dado que se mostraram simples, não dispendiosas e rápidas, podendo eventualmente adequar-se a estudos de rastreio em larga escala.