ADMA Levels Research Articles

AB0574 A Prospective Follow-Up of Young, Male Patients with Behcet's Disease without Major Organ Involvement

ObjectivesVascular involvement, especially in young males, is one of the main causes of mortality and morbidity in Behcet's Disease (BD). However, the prognosis and predictors of vascular involvement is unsufficiently...

OP-220 Asymmetric Dimethylarginine and Augmentation Index in Newly Diagnosed Patients With Hypertension

Pulse wave velocity (PWV), augmentation index (Aix), and central aortic pressure (CAP) are arterial stiffness markers of endothelial dysfunction (ED). We investigated the relationship between arterial stiffness parameters and asymmetric dimethylarginine (ADMA; a marker of ED), in newly diagnosed patients with hypertension (n = 101; 61 females). These patients were investigated in accordance with the recommendations of hypertension guidelines. Arterial stiffness was measured, and serum ADMA and C-reactive protein (CRP; a marker of inflammation) levels were determined.

Association of asymmetric dimethylarginine levels with treadmill-stress-test-derived prognosticators

BackgroundAsymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide production. The purpose of this study was to assess the correlation between ADMA and treadmill stress test outcome parameters with known prognostic value, in patients with intermediate risk for coronary artery disease (CAD). MethodsStudy participants were referred for treadmill exercise stress test (EST) due to symptoms of suspected CAD. Participants with prior history of CAD, cerebrovascular events, peripheral artery disease, systemic inflammatory disease or use of anti-inflammatory agents were excluded. ADMA levels were measured before EST. ResultsThe study prospectively enrolled 209 individuals (165 males, aged 58.1±10.9). A significant negative correlation was detected between ADMA and maximal exercise time (r=−0.556, p<0.001), metabolic equivalents (METs) (r=−0.555, p<0.001) and Duke treadmill score (DTS) (r=−0.347, p<0.001). Subjects who exercised to ≥10 METs (n=114) had lower ADMA levels than those who achieved <7 METs (n=30) (0.58±0.06 vs 0.87±0.08μmol/L, p<0.001), and those with DTS<5 (n=63) had higher ADMA (0.75±0.19 vs 0.64±0.15μmol/L, p<0.001) compared to those with DTS ≥5 (n=146). In multivariable analysis, ADMA remained an independent predictor of DTS (R2=0.210; beta=−10.5; 95% confidence interval −14.9 to −6.2; adjusted p<0.001) and METs (R2=0.500; beta −8.5; 95% confidence interval −9.7 to −6.0; adjusted p<0.001) after adjustment for age, BMI, gender, diabetes, smoking status, dyslipidemia, hypertension and family history of premature CAD. ConclusionADMA is correlated to EST parameters with proven prognostic value. This implies that ADMA itself might be a useful prognosticator in patients with suspected CAD.

Enhancer of Zeste Homolog 2 (EZH2) expression and activation in in vivo and in vitro non-alcoholic fatty liver disease (NAFLD)

via dimethylarginine-dimethylaminohydrolase (DDAH). This study investigated whether changes in serum levels of ADMA occur in a rat model of non-alcoholic steatohepatitis (NASH) and what is the mechanism involved. Materials and methods: NASH was induced in Male Wistar rats by 8 weeks of feeding with an MCD diet (methionine/cholinedeficient diet). Blood samples and hepatic biopsies were collected after 1, 2, 3, 4 and 8 weeks. Serum hepatic enzymes (AST, ALT and g-GT) and ADMA were evaluated. Hepatic biopsies were used for in situ NAD(P)H autofluorescence detection and for mRNA expression of DDAH and ADMA transporters (CAT-1) by RT-PCR. Tissue DDAH activity and content of lipid peroxides, glutathione and ATP were also quantified. Results: NASH injury was confirmed by altered serum levels of hepatic enzymes. A time dependent decrease in serum ADMA levels andan increase inmRNAexpressionofDDAHandCAT-1were found. The hepatic DDAH activity decreased with a concomitant increase in oxidative stress, as demonstrated by high lipid peroxide levels and low GSH content. A decrease in ATP levels and in the NAD(P)Hbound/free ratio reflecting the mitochondria alterations were detected. Conclusions: These results indicate that the oxidative stress observed can contribute to the reduction of DDAH activity. This enzyme is a cysteine hydrolase that may be inhibited by increased reactive oxygen species associated to mitochondria dysfunction. The observed decrease in serum ADMAmay be due to the increase in ADMA transporter, CAT-1. These data confirm and support the crucial role of the liver in the control of ADMA levels by taking up large amounts of ADMA from the systemic circulation. (Supported by Fondazione Cariplo, grant no. 2011-0439.)

Protective effect of oxymatrine on chronic heart failure and ADMA metabolism pathway in isoproterenol-induced chronic heart failure in rats

To investigate the protective effects of oxymatrine on chronic heart failure induced by isoproterenol (ISO) and to observe its effects on ADMA metabolism pathway in ISO-induced chronic heart failure in rats. Male Sprague-Dawley rats were given oxymatrine (100,50 mg kg-1) orally for 14 days. Heart failure was induced in rats by subcutaneous injection of isoproterenol (5 mg kg-1 d-1 ) at the 8th day for 1 week. Serum parameters, haemodynamic parameters, Heart weight, and histopathological variables were analysed. Expression of protein levels were measured by Western blot. Oxymatrine (100,50 mg kg-1) significantly attenuated serum content of cTn I, improved left ventricle systolic and diastolic function and left ventricular remodeling, reduced the ISO-induced myocardial pathological changes compared with ISO group. In addition, oxymatrine (100,50 mg kg-1) significantly reduced serum level of ADMA (P <0. 01), normalize the reduced dimethylarginine dimethylaminohydrolase 2 (DDAH2) expression (P <0. 01) , but had no effect on the isoproterenol-induced upregulated protein arginine methyltransferases 1 expression. Oxymatrine could ameliorate the experimental ventricular remodeling in ISO-induced chronic heart failure in rats and the mechanism involved in reducing serum content of ADMA and increased DDAH2 expression.

Early Exercise Training After Renal Transplantation and Asymmetric Dimethylarginine: The Effect of Obesity

Background/Aims: To assess, in a prospective cohort study of 238 renal transplant patients, our hypothesis that elevated ADMA levels may be influenced by physical exercise and obesity. Methods: Blood samples before and after six months were obtained from 116 transplant patients participating in an aerobic exercise (Group I). A control group consisted of 122 matched transplant patients who did not exercise regularly (Group II). Results: There were no significant differences in ADMA levels between both groups before the training program (Group I_B vs Group II_B). After six months of exercise, ADMA levels in Group I decreased (Group I_B vs Group I_A : 3.50 ± 0.45 vs 2.11 ± 0.35μmol/L; p< 0.01) and were lower compared to those in Group II (Group I_A vs Group II_A : 2 11 ± 0 23 vs 3 25 ± 0 34μmol/L; p< 0 01) Analysis of our results in obese renal transplant recipients (BMI B 30 kg/m²) confirmed a smaller effect of exercise training (Group I_BO vs Group I_AO : 3 75 ± 0 52 vs 3 45 ± 0 45; p< 0 05 and Group I_AO vs Group II_AO : 3.45 ± 0.45 vs 3.74 ± 0.62; p<0.05). Blood lipids, HbA_1C, insulin, and systolic BP were also affected by the training program. Conclusion: Elevated ADMA levels were significantly decreased by early exercise after renal transplantation. The effect of exercise was smaller in obese patients.

Changes in ADMA/DDAH pathway after hepatic ischemia/reperfusion injury in rats: the role of bile.

We investigated the effects of hepatic ischemia/reperfusion (I/R) injury on asymmetric dimethylarginine (ADMA, a nitric oxide synthase inhibitor), protein methyltransferase (PRMT) and dimethylarginine dimethylaminohydrolase (DDAH) (involved, resp., in ADMA synthesis and degradation), and the cationic transporter (CAT). Male Wistar rats were subjected to 30 or 60 min hepatic ischemia followed by 60 min reperfusion. ADMA levels in serum and bile were determined. Tissue ADMA, DDAH activity, DDAH-1 and CAT-2 protein, DDAH-1 and PRMT-1 mRNA expression, GSH/GSSG, ROS production, and lipid peroxidation were detected. ADMA was found in bile. I/R increased serum and bile ADMA levels while an intracellular decrease was detected after 60 min ischemia. Decreased DDAH activity, mRNA, and protein expression were observed at the end of reperfusion. No significant difference was observed in GSH/GSSG, ROS, lipid peroxidation, and CAT-2; a decrease in PRMT-1 mRNA expression was found after I/R. Liver is responsible for the biliary excretion of ADMA, as documented here for the first time, and I/R injury is associated with an oxidative stress-independent alteration in DDAH activity. These data are a step forward in the understanding of the pathways that regulate serum, tissue, and biliary levels of ADMA in which DDAH enzyme plays a crucial role.

Roles of the Oxidative Stress and ADMA in the Development of Deep Venous Thrombosis.

Venous thromboembolism has multifactorial origin and occurs in the context of complex interactions between environmental and genetic predisposing factors. Oxidative stress plays an important role in the physiopathology of venous thrombosis. Current study examined the role of oxidative stress and asymmetric dimethylarginine in the development of DVT with the parameters such as serum malondialdehyde (MDA), glutathione peroxidase (GSH-Px), catalase, ADMA, homocysteine, folic acid, vitamin B6, and vitamin B12 levels. Serum MDA levels were found significantly (P < 0.005) high in patients with DVT compared with control group. Additionally, serum B6 levels were found significantly (P < 0.009) low in patients with DVT compared with healthy volunteers. There were no significant differences between the groups in terms of the other parameters (P > 0.05). This study showed that patients with DVT have increased oxidative stress compared with the healthy volunteers whereas there was no significant difference between the groups in terms of serum ADMA levels. Thus serum ADMA levels seemed to be not related with development of DVT.

Asymmetric dimethylarginine is related to the predicted stroke risk in middle-aged Japanese men

BackgroundAsymmetric dimethylarginine (ADMA) has recently been investigated as a risk marker for cardio- and cerebrovascular diseases. However, whether ADMA levels are related to the risk of stroke in the Japanese general population remains unclear. MethodsWe examined 769 Japanese men (mean age, 47±5years) undergoing health examinations. Each subject's ADMA level and various vascular risk factors were assessed; the predicted 10-year stroke risk was calculated using the point-based prediction model from the Japan Public Health Center Study. ResultsIn a multiple linear regression analysis, age, body mass index, estimated glomerular filtration rate, and current smoking status were significant independent determinants of ADMA levels. A significant odds ratio (OR) for high predicted stroke risk (10-year risk≥5%)was noted in the highest quartile of ADMA levels (OR, 2.47; 95% CI, 1.002–6.07), compared with the lowest quartile, after adjusting for potential confounding factors. A significant OR for high predicted stroke risk was also found for each standard deviation increment in ADMA level (adjusted OR, 1.46; 95% CI, 1.10–1.92). ConclusionElevated ADMA levels were significantly associated with an increased predicted stroke risk, suggesting that measuring ADMA levels may be useful for identifying middle-aged Japanese men with a high risk of stroke.

Asymmetric Dimethylarginine and Augmentation Index in Newly Diagnosed Patients With Hypertension

Pulse wave velocity (PWV), augmentation index (Aix), and central aortic pressure (CAP) are arterial stiffness markers of endothelial dysfunction (ED). We investigated the relationship between arterial stiffness parameters and asymmetric dimethylarginine (ADMA; a marker of ED), in newly diagnosed patients with hypertension (n = 101; 61 females). These patients were investigated in accordance with the recommendations of hypertension guidelines. Arterial stiffness was measured, and serum ADMA and C-reactive protein (CRP; a marker of inflammation) levels were determined. In both women and men, there was no difference in terms of age, body mass index, systolic and diastolic blood pressures, PWV, CAP and the levels of ADMA, while Aix and CRP levels were significantly higher in women (P = .004, P = .046, respectively). In the whole group, ADMA levels correlated with Aix (Pearson r = .237, P = .024). Our findings provide further evidence of a link between arterial stiffness and ED in newly diagnosed patients with hypertension.

Protective effect of CDP-choline on ischemia-reperfusion-induced myocardial tissue injury in rats

CDP-choline exerts tissue protective effect in several ischemic conditions. Recently we have reported that the drug prevents cardiac arrhythmias and improves survival rate in short-term myocardial ischemia reperfusion in rats. In the current study, we determined the effect of intravenously administered CDP-choline on myocardial tissue injury induced by 30-min ischemia followed by 3-h reperfusion in anesthetized rats. Myocardial ischemia was produced by ligature of the left main coronary artery. CDP-choline (100-500 mg/kg) was intravenously injected in the middle of the ischemic period. Cardiovascular parameters were recorded through the experimental period. At the end of the reperfusion period, the hearts of the animals were removed and stained for the investigation of tissue necrosis and apoptosis. The infarct size was evaluated as the ratio of the infarct area to the risk area. Apoptotic activation was assessed by TUNEL assay. Also the blood samples of rats were collected for the measurement of M30-M65, ADMA, homocysteine, and lactate levels. Ischemia/reperfusion caused serious injury in myocardium, increased blood ADMA and lactate levels without influencing other parameters. CDP-choline significantly reduced the infarct size and the number of apoptotic cells in the risk area. Blood pressure increased after CDP-choline injection; however, it returned back to the basal levels before the onset of reperfusion. CDP-choline failed to alter any other measured parameters. The present results demonstrate that intravenously administered CDP-choline is able to protect myocardium from injury induced by long-term coronary occlusion-reperfusion in rats. The inhibition of apoptosis by the drug may contribute to its protective effect. But neither the increase in blood pressure in response to CDP-choline injection nor changes in plasma ADMA concentration appear to mediate the attenuation of the myocardial injury.

Abstract 19058: Role of Agxt2 in Metabolism of Adma in the Settings of Acute Elevation of Systemic Adma Levels

Background: Endogenous inhibitor of nitric oxide synthases asymmetric dimethylarginine (ADMA) has been proposed to serve as an independent cardiovascular risk factor. The major pathway of ADMA degradation is hydrolysis catalyzed by dimethylarginine dimethylaminohydrolase (DDAH). ADMA can also be metabolized through a different pathway, by alanine:glyoxylate aminotransferase 2 (AGXT2), with the formation of α-keto-δ-(N,N-dimethylguanidino)valeric acid (DMGV). The goal of this study was to better characterize the role of the AGXT2 pathway in metabolism of ADMA in vivo using a recently developed assay for detection of DMGV in biological samples. Methods: ADMA (250 μmol x kg-1 x d-1) was infused in C57/BL6 mice for 3 days using osmotic minipumps implanted intraperitoneally. We performed bilateral nephrectomy in some of the mice 24 hours before the end of ADMA infusion and sample collection. Measurements of ADMA and DMGV were performed LC-MS/MS. Results: Infusion of ADMA for 3 days resulted in a 3.4 fold increase in plasma and in a 5.2 fold increase in urine ADMA levels. Elevation of ADMA concentration coincided with elevation of plasma and urine DMGV levels (2.9 and 3.9 folds respectively). Bilateral nephrectomy in the mice, which did not undergo ADMA infusion, did not increase plasma ADMA levels, while bilateral nephrectomy in the mice, which underwent ADMA infusion, led to a 1.7 fold increase in plasma ADMA levels and a 17.6 fold increase in DMGV levels. Neither bilateral nephrectomy nor infusion of ADMA for 3 days changed the AGXT2 mRNA levels in the liver. Conclusions: Infusion of ADMA leads to increased flux through the AGXT2 pathway of ADMA metabolism in vivo. The observation that each 1 μmol / mmol creatinine increase in ADMA level in urine leads to about 1 μmol / mmol creatinine increase in urine DMGV level suggests that AGXT2 is a major enzyme regulating ADMA levels in urine. The marked increase in DMGV levels in the mice lacking both kidneys suggests significant extrarenal production of DMGV in addition to absent renal excretion. Lack of increase in plasma ADMA levels after nephrectomy in mice infused with saline suggests that ADMA-metabolyzing ezymes are able to compensate for lack of renal excretion of ADMA in our model.

Age-related changes in ADMA–DDAH–NO pathway in rat liver subjected to partial ischemia followed by global reperfusion

BackgroundLiver function is affected during ischemia/reperfusion (IR). We evaluated the effect of the aging process on selected parameters determining the NO level in rat liver subjected to IR. MethodsThe animals were divided into the C-2 and the IR-2 group of young rats (2–4months old) and the C-12 and the IR-12 group of older rats (12–14months old). Livers belonging to the IR-2 and the IR-12 group were subjected to partial ischemia (60min) and reperfusion (4h). Blood samples were obtained after surgeries to estimate the activity of aminotransferases, as well as just before ischemia and during reperfusion (15, 120, and 240min) to estimate concentration of arginine (Arg) and its derivatives: asymmetric and symmetric dimethylarginine (ADMA, SDMA). After IR, dimethylarginine dimethylaminohydrolase (DDAH) activity and protein concentration of inducible nitric oxide synthase (iNOS) were measured in liver homogenates. ResultsIn the IR-2 group ADMA level increased the most between 15 and 120min of reperfusion and was the highest of all the groups (0.72±0.2μmol/l). In the IR-12 group ADMA level decreased significantly and was lower compared to all the other groups at 15min (0.42±0.2μmol/l) and to IR-2 at 120 (0.52±0.1μmol/l) and 240min (0.38±0.1μmol/l) of reperfusion. Only the IR-2 group SDMA level increased significantly between 15 (0.75±0.9μmol/l) and 240min (1.0±1.2μmol/l) of reperfusion. At the beginning of the surgery the Arg level was significantly higher in young rats (C-2: 102.1±35.7μmol/l; IR-2: 114.63±28.9μmol/l) than in older ones (C-12: 41.88±44.7μmol/l; IR-12: 28.64±30.6μmol/l). In the C-2 group the Arg level (77.41±37.5μmol/l) and Arg/ADMA (A/A) ratio (138.03±62.8μmol/l) were significantly higher compared to the ischemic groups at 15min and to all the other groups at 120 (Arg: 47.17±31.7μmol/l; A/A: 88.28±66.2μmol/l) and 240min (Arg: 43.87±21.9μmol/l; A/A: 118.02±106.3μmol/l). In the IR-2 group Arg level (11.4±12.0μmol/l) and A/A ratio (16.11±16.2μmol/l) decreased significantly at 15min and during the next phase of reperfusion the levels of those parameters were low, comparably to those in IR-12. As a result of IR, a decrease in DDAH activity and an increase in iNOS protein concentration were observed only in the young rats. ConclusionsWe found that in the non-ischemic groups the Arg level may be affected by the aging process. Under IR conditions, important changes in DDAH–ADMA–NO pathway were observed only in young livers.

Endothelial dysfunction in patients with history of pulmonary embolism

Purpose: Dysfunction of the vascular endothelium is a hallmark of most conditions associated with atherosclerosis. Recent data indicate that endothelial dysfunction (ED) is common link of both atherosclerosis and venous thromboembolism. In order to evaluate endothelial function in patients with history of pulmonary embolism (PE), we measured flow-mediated dilation (FMD) of the brachial artery and assessed the biomarkers of endothelial dysfunction (sVCAM-1 and ADMA). Methods: We enrolled 52 patients (37F, age 37±11.3 yrs) with history of PE (mean 1.1±0.7 yr before the study) without significant co-morbidities and compared with 52 healthy controls (21F, age 39.5±11 yrs). Brachial artery diameter responses to hyperemic flow and glyceryl trinitrate spray were measured using high-resolution ultrasound. Flow-mediated dilation and nitroglycerin-induced dilation was defined as maximum percentage changes in the vessel diameter. We also evaluated serum ADMA (ADMA Xpress ELISA; Immunodiagnostic AG) and sVCAM- 1 serum levels (Human sVCAM-1, Biovendor). Results: PE patients had significantly impaired FMD compared with controls (6.1±4.1% vs 13.8±6.8%, p=0.0001). PE patients had also significantly lower nitroglycerin-induced dilation compared with controls (20.7±6.3% vs 26.5±11.7%, p=0.003). The serum level of ADMA was higher in PE patients (0.53±0.16 μmol/l vs 0.45±0.14 μmol/l, p= 0.02), while sVCAM-1 did not differ significantly (601.83±342.4 ng/ml vs 568.47±204.6 ng/ml, p=0.5). Interestingly, serum sVCAM-1 concentration correlated with baseline diameter of brachial artery (r=0.22, p=0.03), diameter after FMD (r=0.18, p=0.06), diameter after nitroglycerin (r=0.25, p=0.01) and with ADMA levels (r=0.32, p=0.005). Conclusions: Patients after episode of PE have impaired endothelial function assessed by FMD and biomarker levels. Our findings confirm that endothelial dysfunction might be associated with venous thromboembolism.

Assessment of l-arginine asymmetric 1 dimethyl (ADMA) in early-onset and late-onset (severe) preeclampsia

Preeclampsia (PE) is characterized by hypertension and proteinuria. It has been classified in early or late according to gestational age at the onset of disease. Endothelial dysfunction plays a crucial part in its pathogenesis. NO is a potent vasodilator and ADMA is its endogenous inhibitor. We have assessed maternal ADMA levels. ADMA were increased in early [0.66μmol/L] versus late sPE [0.47μmol/L] (P=0.001) and versus normotensive pregnant [0.48μmol/L] (P=0.001). Our findings suggest that high ADMA levels in early sPE could compromise NO synthesis contributing to endothelial dysfunction, leading to impaired placentation and the onset of this disease.

Alzheimer’s disease treated patients showed different patterns for oxidative stress and inflammation markers

Alzheimer's disease (AD) is the most common type of dementia accounting for 60-80% of the reported cases. The aim of this study was to evaluate levels of certain parameters of oxidative stress and markers of endothelial dysfunction in the blood of 21 AD patients under standard treatment compared with 10 controls, in an attempt to elucidate the contribution of AD to the total oxidative stress status of the patients. Results indicate that IL-6, TNF-α, ADMA and homocysteine levels were significantly elevated in AD patients. Protein carbonyls levels were higher in AD group, while glutathione reductase and total antioxidant capacity were lower, depicting decreased defense ability against reactive oxygen species. Besides, a higher level of advanced glycation end-products was observed in AD patients. Depending on the treatment received, a distinct inflammatory and oxidative stress profile was observed: in Rivastigmine-treated group, IL6 levels were 47% lower than the average value of the remaining AD patients; homocysteine and glutathione reductase were statistically unchanged in the Rivastigmine and Donepezil-Memantine, respectively Donepezil group. Although the study is based on a limited population, the results could constitute the basis for further studies regarding the effect of medication and diet on AD patients.

Global protein and histone arginine methylation are affected in a tissue-specific manner in a rat model of diet-induced hyperhomocysteinemia

Accumulation of S-adenosylhomocysteine (AdoHcy), the homocysteine (Hcy) precursor and a potent methyltransferase inhibitor, may mediate the neurological and vascular complications associated with elevated Hcy. Protein arginine methylation is a crucial post-translational modification and generates monomethylarginine (MMA) and dimethylarginine (asymmetric, ADMA, and symmetric, SDMA) residues. We aimed at determining whether protein arginine methylation status is disturbed in an animal model of diet-induced hyperhomocysteinemia (HHcy). HHcy was achieved by dietary manipulation of Wistar rats: methionine-enrichment (HM), B vitamins deficiency (LV), or both (HMLV). Total Hcy, S-adenosylmethionine (AdoMet), AdoHcy, MMA, ADMA and SDMA concentrations in plasma or tissues (heart, brain and liver) were determined by adequate high-performance liquid chromatography or liquid chromatography-electrospray ionization-tandem mass spectrometry methods. Moreover, in tissues from the HMLV group, histone arginine asymmetric dimethylation was evaluated by Western blotting, and the histone methylation marks H3R17me2a, H3R8me2a and H4R3me2a were studied. HHcy was induced by all special diets, with elevation of AdoHcy concentrations in liver (LV and HMLV) and heart (HMLV) (all versus control). Plasma ADMA levels were lower in all hyperhomocysteinemic animals. Protein-incorporated ADMA levels were decreased in brain and in heart (both for the LV and HMLV groups). Moreover, in brain of animals exposed to the HMLV diet, the H3R8me2a mark was profoundly decreased. In conclusion, our results show that diet-induced Hcy elevation disturbs global protein arginine methylation in a tissue-specific manner and affects histone arginine methylation in brain. Future research is warranted to disclose the functional implications of the global protein and histone arginine hypomethylation triggered by Hcy elevation.

Premature Aging of Cardiovascular/Platelet Function in Polycystic Ovarian Syndrome

ObjectiveThe objective of this study was to compare the impact of aging on nitric oxide (NO) modulation of platelet and vascular function in healthy women and women with polycystic ovary syndrome. Methods and ResultsA case-control study of women ages 18 to 60 years, comparing women with polycystic ovarian syndrome against age-matched healthy controls, was performed. A total of 242 women, of whom 109 had polycystic ovarian syndrome (based on Rotterdam criteria), participated in the study. Women who were pregnant or on clopidogrel were excluded from the study. Inhibition of platelet aggregation by nitric oxide (primary outcome measure), vascular endothelial function, plasma concentrations of NG, NG-dimethyl-L-arginine (ADMA), endothelial progenitor cell count, and high-sensitivity C-reactive protein (markers of endothelial dysfunction and inflammation) were assessed. With increasing age in control women, there was progressive attenuation of platelet responses to NO, impairment of endothelial function, and elevation of ADMA levels (P ≤.001). Irrespective of age, women with polycystic ovarian syndrome exhibited greater impairment of all these parameters (all P <.05, 2-way analysis of variance) and demonstrated these anomalies earlier in life. ConclusionsNormal aging in women is associated with attenuation of NO-based signaling in platelets and blood vessels. In women with polycystic ovarian syndrome, these changes are present from early adult life and may contribute to premature atherogenesis.

Relationship between adiponectin and nitrite in healthy and preeclampsia pregnancies

BackgroundControversial results have been reported regarding plasma adiponectin levels in preeclampsia (PE) compared to healthy pregnancies (HP). Adiponectin activates eNOS, increasing the levels of the vasodilator nitric oxide (NO). PE reduces the levels of nitrite (an NO marker) and induces higher levels of ADMA (an endogenous eNOS inhibitor) compared to HP. No previous study has examined whether a positive correlation exists between adiponectin and nitrite in HP and PE and how ADMA may interfere with this correlation. MethodsWe measured plasma nitrite concentrations using an ozone-based chemiluminescence assay, and plasma ADMA and adiponectin levels using enzyme immunoassays in 117 pregnant women (70 healthy and 47 preeclamptic). ResultsWe found higher adiponectin levels (23.6±13.0 vs. 17.8±5.6µg/ml; P<0.05) and lower plasma nitrite levels (104.5±84.3 vs. 177.2±151.3 nM; P<0.05) in PE compared to HP. We found a significant positive correlation between these markers in HP (r=0.3; P<0.05), but no correlation in PE. However, when we grouped PE women regarding ADMA levels (low and high levels), a strong positive correlation was found in the group with lower ADMA levels (r=0.67; P<0.05), suggesting that high ADMA concentrations may interfere with the physiological activation of eNOS by adiponectin in PE. ConclusionsOur findings showed higher levels of adiponectin and lower nitrite levels in PE compared to HP, and these levels were positively correlated in HP and in PE presenting lower concentrations of ADMA.

Abstract 219: Agxt2 Plays Important Role in Regulation of Urine Adma Levels After Acute Adma Loading in Mice

Background Multiple epidemiological studies demonstrated increased levels of an endogenous inhibitor of nitric oxide synthases asymmetric dimethylarginine (ADMA) in cardiovascular diseases. In addition to the well characterized pathway of ADMA hydrolysis by dimethylarginine dimethylaminohydrolase (DDAH) ADMA can also be metabolized through an alternative pathway by alanine:glyoxylate aminotransferase 2 (AGXT2), which converts ADMA to α-keto-δ-(N,N-dimethylguanidino)valeric acid (DMGV). The goal of this study was to better characterize the role of AGXT2 pathway in metabolism of ADMA in vivo using a recently developed assay for detection of DMGV in biological samples. Methods ADMA (250 μmol x kg-1 x d-1) was infused in C57/BL6 mice for 3 days using osmotic minipumps implanted intraperitoneally. We performed bilateral nephrectomy in some of the mice 24 hours before the end of ADMA infusion and sample collection. Urine was collected for 24 hours in metabolic cages. Blood was collected by cardiac puncture. Measurements of ADMA and DMGV were performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results Intraperitoneal infusion of ADMA for 3 days resulted in an increase in plasma ADMA levels from 0.46±0.045 to 1.57±0.40 μM (p&lt;0.05) and in urine ADMA levels from 36.4±3.4 to 188.6±31.5 μmol / mmol creatinine (p&lt;0.05). Elevation of ADMA concentration coincided with elevation of plasma DMGV levels from 0.21±0.025 to 0.61±0.14 μM (p&lt;0.05) and urine DMGV levels from 41.4±3.2 to 162.5±32.9 μmol / mmol creatinine (p&lt;0.05). Bilateral nephrectomy in the mice, which underwent ADMA infusion, lead to a 1.7 fold increase in plasma ADMA levels and a 17.6 fold increase in DMGV levels compared with the mice from the sham group. Conclusions Infusion of ADMA leads to increased flux through the AGXT2 pathway of ADMA metabolism in vivo. The observation that each 1 μmol / mmol creatinine increase in ADMA level in urine leads to a ~1 μmol / mmol creatinine increase in urine DMGV level suggests that AGXT2 is a major enzyme regulating ADMA levels in urine. The marked increase in DMGV levels in the mice lacking both kidneys suggests significant extrarenal production of DMGV in addition to absent renal excretion.