Asymmetric dimethylarginine (ADMA) induces vascular endothelium impairment and aggravates post-ischemic ventricular dysfunction in rats

Maternal resveratrol therapy protected adult rat offspring against hypertension programmed by combined exposures to asymmetric dimethylarginine and trimethylamine-N-oxide

Resveratrol, a phytochemical, has shown antioxidant properties and potential benefits in hypertension. Asymmetric dimethylarginine (ADMA)-related nitric oxide deficiency and gut microbiota-derived metabolite trimethylamine-N-oxide (TMAO) have been linked to hypertension. We aimed to test whether maternal resveratrol therapy would protect adult offspring against hypertension programmed by prenatal exposure to ADMA and TMAO. Pregnant Sprague-Dawley rats received ADMA 10 mg/kg/day (A), TMAO 0.65 mg/hr (T), ADMA+TMAO (AT), or vesicle (CV). One group of ADMA+TMAO-exposed rats received 50 mg/L of resveratrol in drinking water during pregnancy and lactation periods (ATR). Male offspring (n = 8/group) were assigned to five groups: CV, A, T, AT, and ATR. Rats were killed at 12 weeks of age. ADMA exposure caused the elevation of blood pressure in 12-week-old male offspring, which was exacerbated by TMAO exposure. Treatment with resveratrol rescued hypertension programmed by combined ADMA and TMAO exposure. This was accompanied by alterations in the compositions of gut microbiota and increased fecal butyrate levels. Both the abundance of the butyrate-producing genera Lachnospiraceae and Ruminococcaceae were augmented by resveratrol. Meanwhile, resveratrol therapy significantly increased the abundance of the Cyanobiaceae and Erysipelotrichaceae families. Moreover, the protective effects of resveratrol were related to the mediation of the renin-angiotensin system . Our data provide new insights into the protective mechanisms of resveratrol against hypertension programmed by ADMA and TMAO, including regulation of gut microbiota and their metabolites, the renin-angiotensin system, and nitric oxide pathway. Resveratrol might be a potential reprogramming strategy to protect against the hypertension of developmental origins.

A relative L-arginine deficiency contributes to endothelial dysfunction across the stages of the menopausal transition

Vascular endothelial function declines across the menopause transition in women. We tested the hypothesis that reduced availability of the endothelial nitric oxide synthase [eNOS] substrate L‐arginine is an underlying mechanism to vascular endothelial dysfunction across menopause stages. Endothelial function (brachial artery flow‐mediated dilation [FMD]) and plasma markers of L‐arginine metabolism (citrulline, N^G‐mono‐methyl‐ւ‐arginine [L‐NMMA] asymmetric dimethylarginine [ADMA] and N^G‐N^′G‐dimethyl‐l‐arginine [SDMA]), were measured in 129 women: 36 premenopausal (33 ± 7 years), 16 early‐ (49 ± 3 years) or 21 late‐ (50 ± 4 years) perimenopausal, and 21 early‐ (55 ± 3 years) or 35 late‐ (61 ± 4 years) postmenopausal. FMD was progressively reduced across menopause stages (P < 0.001). Menopause stage was associated with L‐arginine concentrations (P = 0.012), with higher levels in early postmenopausal compared to early and late perimenopausal women (P < 0.05). The methylarginine and eNOS inhibitor L‐NMMA was higher in early and late postmenopausal women compared to premenopausal and early and late perimenopausal women (all P < 0.001), and was inversely correlated with FMD (r = −0.30, P = 0.001). The L‐arginine/L‐NMMA ratio, a potential biomarker of relative L‐arginine levels, was lower in postmenopausal compared to either premenopausal or perimenopausal women (both P < 0.001), and was positively correlated with FMD (r = 0.33, P < 0.001). There were no differences in plasma citrulline, ADMA or SDMA across groups. These data suggest that a relative L‐arginine deficiency may be a mechanism underlying the decline in endothelial function with the menopause transition in women. The relative L‐arginine deficiency may be related to elevated levels of the methylarginine L‐NMMA, which would compete with L‐arginine for eNOS and for intracellular transport, reducing NO biosynthesis.

Asymmetric dimethylarginine, a biomarker of cardiovascular complications in diabetes mellitus

Cardiovascular (CV) complications are an essential causal element of prospect in diabetes mellitus (DM), with carotid atherosclerosis being a common risk factor for prospective crisis of coronary artery diseases and/or cerebral infarction in DM subjects. From another point of view, asymmetric dimethylarginine (ADMA) has been established as an inhibitor of endogenous nitric oxide synthesis and the relationship between ADMA and arteriosclerosis has been reported. In our study with 87 type 2 DM (T2DM) patients, we have examined whether ADMA and other CV risk factors are the useful predictors of DMCV complications. After the measurement of the respective CV risk factors, we have followed the enrolled T2DM patients for 5 years. We have finally analyzed 77 patients. DMCV complications developed in 15 cases newly within 5 years, and 4 cases recurred. The concentrations of ADMA in plasma were markedly more elevated in 19 DM patients with CV complications than in 58 DM patients without CV complications. Urinary albumin (U-Alb), mean intimal-medial thickness (IMT) and ankle brachial index (ABI) were also higher in patients with CV complications. Multiple regression analyses showed that U-Alb had an influence on the high level of ADMA (standardized β = 6.59, P = 0.00014) independently of age, systolic BP, fibrinogen, mean IMT, plaque score, and ABI. The review indicates what is presently known regarding plasma ADMA that might be a new and meaningful biomarker of CV complications in DM subjects.

Beyond the joint: Subclinical atherosclerosis in rheumatoid arthritis

Rheumatoid arthritis is a chronic autoimmune inflammatory disease associated with increased cardiovascular risk and higher mortality in respect to general population. Beyond joint disease, inflammation is the major determinant of accelerated atherosclerosis observed in rheumatoid arthritis. We review the relationship between inflammation, atherosclerosis and cardiovascular risk in rheumatoid arthritis, focusing on the assessment of subclinical atherosclerosis by functional and morphological methods. These tools include flow mediated dilatation, carotid intima-media thickness, ankle/brachial index, coronary calcium content, pulse wave analysis and serum biomarker of subclinical atherosclerosis.

Apelin-13 deteriorates hypertension in rats after damage of the vascular endothelium by ADMA

Asymmetric dimethylarginine (ADMA) is a risk factor for endothelial dysfunction. The polypeptide apelin has biphasic effects on blood vessels in vivo and in vitro. We investigated the effect of apelin-13 on ADMA-damaged vessels. Rats were divided among ADMA-treated and control groups, which were treated with ADMA (10 mg·(kg body mass)−1·day−1) or saline, respectively, for 4 weeks. Systolic blood pressure (SBP) was measured before and after the injection of apelin-13. The ultrastructure of endothelial cells in caudal arteries was examined using transmission electron microscopy. The reactivities of isolated caudal artery rings were observed after exposure to apelin-13, and myosin light chain (MLC) phosphorylation was assessed by immunohistochemistry in rings treated with or without apelin-13. ADMA induced hypertension and endothelial dysfunction. After injection of apelin-13, SBP declined in the control group but was elevated in the ADMA-treated group. In vitro, apelin-13 caused relaxation in rings in the control group, but it contracted rings in the ADMA-treated group. Apelin-13 promoted MLC phosphorylation in vascular smooth muscle cells (VSMCs) in the ADMA group. These results indicate that apelin-13 might pass through ADMA-damaged endothelium and act on VSMCs to increase MLC phosphorylation, thus contributing to vasoconstriction and exacerbating hypertension.

AVE3085 protects coronary endothelium from the impairment of asymmetric dimethylarginine by activation and recoupling of eNOS

PURPOSE

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of eNOS and it is recognized as a risk factor for endothelial dysfunction in cardiovascular diseases. We investigated the effect of AVE3085, a newly developed transcription enhancer of eNOS, on ADMA-induced endothelial dysfunction in coronary arteries with underlying mechanisms explored.

METHODS

Porcine coronary small arteries (diameter 600-800 μm) were studied in a myograph for endothelium-dependent relaxation to bradykinin and endothelium-independent relaxation to sodium nitroprusside. Protein expressions of eNOS and phosphorylated-eNOS (p-eNOS(Ser1177) and p-eNOS(Thr495)), and nitrotyrosine formation were determined by Western blot. NO release was directly measured with a NO microsensor. Productions of O(2) (.-) and peroxynitrite (ONOO(-)) were determined by lucigenin- and luminol- enhanced chemiluminescence respectively.

RESULTS

Exposure to ADMA significantly decreased the bradykinin-induced vasorelaxation and reduced the protein expression of p-eNOS(Ser1177) whereas increased the expression of p-eNOS(Thr495) and nitrotyrosine. Pre-incubation with AVE3085 restored the bradykinin-induced relaxation, reversed the decrease of p-eNOS(Ser1177), and lowered the level of p-eNOS(Thr495) and nitrotyrosine. NO release in response to bradykinin was significantly reduced by ADMA and such reduction was restored by AVE3085. AVE3085 also prevented the elevation of O (2) (.-) and ONOO(-) levels in coronary arteries exposed to ADMA.

CONCLUSIONS

AVE3085 prevents ADMA-induced endothelial dysfunction in coronary arteries. The protective effect of AVE3085 may be attributed to increased NO production resulting from enhanced eNOS activation, and decreased oxidative stress that involves inhibition of O (2) (.-) generation by eNOS recoupling. The present study suggested the therapeutic potential of AVE3085 in endothelial dysfunction in cardiovascular disorders.

L-arginine and asymmetric dimethylarginine are early predictors for survival in septic patients with acute liver failure

Dysfunctions of the L-arginine (L-arg)/nitric-oxide (NO) pathway are suspected to be important for the pathogenesis of multiple organ dysfunction syndrome (MODS) in septic shock. Therefore plasma concentrations of L-arg and asymmetric dimethylarginine (ADMA) were measured in 60 patients with septic shock, 30 surgical patients and 30 healthy volunteers using enzyme linked immunosorbent assay (ELISA) kits. Plasma samples from patients with septic shock were collected at sepsis onset, and 24 h, 4 d, 7 d, 14 d and 28 d later. Samples from surgical patients were collected prior to surgery, immediately after the end of the surgical procedure as well as 24 h later and from healthy volunteers once. In comparison to healthy volunteers and surgical patients, individuals with septic shock showed significantly increased levels of ADMA, as well as a decrease in the ratio of L-arg and ADMA at all timepoints. In septic patients with an acute liver failure (ALF), plasma levels of ADMA and L-arg were significantly increased in comparison to septic patients with an intact hepatic function. In summary it can be stated, that bioavailability of NO is reduced in septic shock. Moreover, measurements of ADMA and L-arg appear to be early predictors for survival in patients with sepsis-associated ALF.

Regulation of endothelial nitric oxide synthase and asymmetric dimethylarginine by matrine attenuates isoproterenol-induced acute myocardial injury in rats

OBJECTIVES

This study was designed to investigate the cardioprotective effects of matrine on regulation of endothelial nitric oxide synthase (eNOS) and asymmetric dimethylarginine (ADMA) in isoproterenol-induced acute myocardial ischaemic rats.

METHODS

Male Sprague-Dawley rats were pretreated with matrine (200, 100 and 50 mg/kg) orally for 10 days. Acute myocardial injury was induced in rats by subcutaneous injection of isoproterenol. Serum and haemodynamic parameters, histopathological variables and expression of protein levels were analysed.

KEY FINDINGS

Oral administration of matrine (200, 100 and 50 mg/kg) significantly attenuated isoproterenol-induced cardiac necrosis and left ventricular dysfunction. Matrine treatment restored impaired ventricular Akt and eNOS protein expression with concomitant increased phosphorylation of Akt (Ser473) and eNOS (Ser1177), and also restored glycogen synthase kinase 3β activity, as indicated by increased phosphorylation at Ser 9. Moreover, treatment with matrine had no effect on the isoproterenol-induced elevated protein arginine methyltransferase 1 protein expression, but could significantly normalize the reduced dimethylarginine dimethylaminohydrolase 2 expression and attenuate the increased serum level of ADMA. The expression of catechol-o-methyltransferase and monoamine oxidase did not differ among all groups (all P > 0.05).

CONCLUSIONS

Our results suggested that matrine protects against isoproterenol-induced myocardial ischaemia via eNOS and ADMA pathway.

Down-regulation of DDAH2 and eNOS induces endothelial dysfunction in sinoaortic-denervated rats

The aim of present study was to investigate whether downregulation of dimethylarginine dimethylaminohydrolase (DDAH2) and endothelial nitric oxide synthase (eNOS) induced endothelial dysfunction in sinoaortic-denervated (SAD) rats. SAD rats exhibited significantly higher blood pressure (BP) variability and markedly lower baroreflex sensitivity. However, there was no significant difference in BP between SAD rats and sham-operated rats. In SAD rats, ultrastructural analysis revealed that endothelial cells were degenerated and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) study showed that apoptotic aortic endothelial cells increased. Circulating angiotensinII (AngII), asymmetric dimethylarginine (ADMA) and malondialdehyde (MDA) levels in SAD rats were similar to sham-operated rats, but aortic AngII and MDA levels locally increased. Endothelium-mediated relaxation of thoracic aorta isolated from SAD rats was impaired compared to sham-operated rats, whereas the sodium nitroprusside-induced relaxation was quite similar. Western blotting results showed that DDAH2 and eNOS expressions decreased significantly in the aortae of SAD rats. Treatment of primary cultured rat aortic endothelial cells with AngII (1 μM) resulted in a marked reduction of DDAH2 and eNOS expressions, and coadministration of losartan (1 μM), an AT(1) receptor antagonist, abolished the effect. In conclusion, downregulation of DDAH2 and eNOS induced endothelial dysfunction in SAD rats. DDAH2 and eNOS may be the potential targets for treatment of endothelial dysfunction.

Asymmetric dimethylarginine, endothelial nitric oxide bioavailability and mortality in sepsis

Background

Plasma concentrations of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, are raised in patients with chronic vascular disease, causing increased cardiovascular risk and endothelial dysfunction, but the role of ADMA in acute inflammatory states is less well defined.

Methods and Results

In a prospective longitudinal study in 67 patients with acute sepsis and 31 controls, digital microvascular reactivity was measured by peripheral arterial tonometry and blood was collected at baseline and 2–4 days later. Plasma ADMA and L-arginine concentrations were determined by high performance liquid chromatography. Baseline plasma L-arginine: ADMA ratio was significantly lower in sepsis patients (median [IQR] 63 [45–103]) than in hospital controls (143 [123–166], p<0.0001) and correlated with microvascular reactivity (r = 0.34, R² = 0.12, p = 0.02). Baseline plasma ADMA was independently associated with 28-day mortality (Odds ratio [95% CI] for death in those in the highest quartile (≥0.66 µmol/L) = 20.8 [2.2–195.0], p = 0.008), and was independently correlated with severity of organ failure. Increase in ADMA over time correlated with increase in organ failure and decrease in microvascular reactivity.

Conclusions

Impaired endothelial and microvascular function due to decreased endothelial NO bioavailability is a potential mechanism linking increased plasma ADMA with organ failure and death in sepsis.

Differential sensitivity of basal and acetylcholine-induced activity of nitric oxide to blockade by asymmetric dimethylarginine in the rat aorta

BACKGROUND AND PURPOSE

Previous work has shown that N(G)-monomethyl-l-arginine (l-NMMA) paradoxically inhibits basal, but not ACh-stimulated activity of nitric oxide in rat aorta. The aim of this study was to determine if the endogenously produced agent, asymmetric N(G), N(G)-dimethyl-l-arginine (ADMA), also exhibits this unusual selective blocking action.

EXPERIMENTAL APPROACH

The effect of ADMA on basal nitric oxide activity was assessed by examining its ability to enhance phenylephrine (PE)-induced tone in endothelium-containing rings. Its effect on ACh-induced relaxation was assessed both in conditions where ADMA greatly enhanced PE tone and where tone was carefully matched with control tissues at a range of different levels.

KEY RESULTS

ADMA (100 microM) potentiated PE-induced contraction, consistent with inhibition of basal nitric oxide activity. Higher concentrations (300-1000 microM) had no greater effect. Although ADMA (100 microM) also appeared to block ACh-induced relaxation when it enhanced PE tone to maximal levels, virtually no block was seen at intermediate levels of tone in the presence of ADMA. Even ADMA at 1000 microM had no effect on the maximal relaxation to ACh, although it produced a small (two- to threefold) reduction in sensitivity. ADMA and l-NMMA, like l-arginine (all at 1000 microM), protected ACh-induced relaxation against blockade by l-NAME (30 microM).

CONCLUSIONS AND IMPLICATIONS

In the rat aorta, ADMA, like l-NMMA, blocks basal activity of nitric oxide, but has little effect on that stimulated by ACh. Further studies are required to explain these seemingly anomalous actions of ADMA and l-NMMA.

Impact of asymmetric dimethylarginine on mortality after acute myocardial infarction

OBJECTIVE

Asymmetrical dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthases. From a prospective cohort of patients with acute myocardial infarction (MI), we aimed to analyze the predictive value of circulating ADMA concentrations on prognosis.

METHODS AND RESULTS

Blood samples from 249 consecutive patients hospitalized for acute MI <24 hours were taken on admission. Serum levels of ADMA and its stereoisomer, symmetrical dimethylarginine (SDMA), were determined using high-performance liquid chromatography. The independent predictors of ADMA were glomerular filtration rate, female sex, and SDMA (R(2)=0. 25). Baseline ADMA levels were higher in patients who had died than in patients who were alive at 1 year follow-up (1.23 [0.98 to 1.56] versus 0.95 [0.77 to 1.20] micromol/L, P<0.001). By Cox multivariate analysis, the higher tertile of ADMA (median [interquartile range]: 1.45 [1.24 to 1.70] micromol/L) was a predictor for mortality (Hazard Ratio [95% CI], 4.83 [1.59 to 14.71]), when compared to lower tertiles, even when adjusted for potential confounders, such as acute therapy, biological, and clinical factors.

CONCLUSIONS

Our study suggests that the baseline ADMA level has a strong prognostic value for mortality after MI, beyond traditional risk factors and biomarkers.

Role of asymmetric dimethylarginine for angiotensin II-induced target organ damage in mice

The aim of the present study was to investigate the role of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) and its degrading enzyme dimethylarginine dimethylaminohydrolase (DDAH) in angiotensin II (ANG II)-induced hypertension and target organ damage in mice. Mice transgenic for the human DDAH1 gene (TG) and wild-type (WT) mice (each, n = 28) were treated with 1.0 microg kg(-1) min(-1) ANG II, 3.0 microg kg(-1) min(-1) ANG II, or phosphate-buffered saline over 4 wk via osmotic minipumps. Blood pressure, as measured by tail cuff, was elevated to the same degree in TG and WT mice. Plasma levels of ADMA were lower in TG than WT mice and were not affected after 4 wk by either dose of ANG II in both TG and WT animals. Oxidative stress within the wall of the aorta, measured by fluorescence microscopy using the dye dihydroethidium, was significantly reduced in TG mice. ANG II-induced glomerulosclerosis was similar between WT and TG mice, whereas renal interstitial fibrosis was significantly reduced in TG compared with WT animals. Renal mRNA expression of protein arginine methyltransferase (PRMT)1 and DDAH2 increased during the infusion of ANG II, whereas PRMT3 and endogenous mouse DDAH1 expression remained unaltered. Chronic infusion of ANG II in mice has no effect on the plasma levels of ADMA after 4 wk. However, an overexpression of DDAH1 alleviates ANG II-induced renal interstitial fibrosis and vascular oxidative stress, suggesting a blood pressure-independent effect of ADMA on ANG II-induced target organ damage.