dimethylarginine and Myocardial-Infarction

The Cardiorenal Syndrome type 4 (CRS-4) defines a pathological condition in which a primary chronic kidney disease (CKD) leads to a chronic impairment of cardiac function. The pathophysiology of CRS-4 and the role of arterial stiffness remain only in part understood. Several uremic toxins, such as uric acid, phosphates, advanced glycation end-products, asymmetric dimethylarginine, and endothelin-1, are also vascular toxins. Their effect on the arterial wall may be direct or mediated by chronic inflammation and oxidative stress. Uremic toxins lead to endothelial dysfunction, intima-media thickening and arterial stiffening. In patients with CRS-4, the increased aortic stiffness results in an increase of cardiac workload and left ventricular hypertrophy whereas the loss of elasticity results in decreased coronary artery perfusion pressure during diastole and increased risk of myocardial infarction. Since the reduction of arterial stiffness is associated with an increased survival in patients with CKD, the understanding of the mechanisms that lead to arterial stiffening in patients with CRS4 may be useful to select potential approaches to improve their outcome. In this review we aim at discussing current understanding of the pathways that link uremic toxins, arterial stiffening and impaired cardiac function in patients with CRS-4.

Topics: Aorta; Arginine; Autonomic Nervous System Diseases; Bone Diseases, Metabolic; Cardio-Renal Syndrome; Cardiovascular Diseases; Chronic Disease; Endothelium, Vascular; Glycation End Products, Advanced; Humans; Inflammation; Myocardial Infarction; Oxidative Stress; Phosphorus; Renal Insufficiency, Chronic; Toxins, Biological; Tunica Intima; Uric Acid; Vascular Stiffness; Vasculitis

Cardiovascular diseases (CVD) are still the most frequent cause of death in Western Europe. Pathophysiological experiments revealed in the last years that the vascular endothelium, as well as a result of the synthesis of nitric oxide (NO), is a crucial regulator of vascular function and homeostasis. The vascular endothelium plays a key role in cardiovascular physiology and pathophysiology, largely via NO-dependent processes. L-Arginine is the substrate for the endothelial NO synthase (eNOS) to generate NO. Endothelial dysfunction is caused by various cardiovascular risk factors. In most studies, acute and chronic administration of L-arginine has been shown to improve endothelial function in animal models of hypercholesterolemia and atherosclerosis. Therefore, numerous studies have been conducted to elucidate whether dietary L-arginine supplementation can augment NO production in humans and thereby improve endothelium-dependent vasodilatation. The most likely mechanism that explains the occurrence of endothelial dysfunction and the effect of L-arginine is that application of L-arginine antagonizes asymmetric dimethylarginine (ADMA), the endogenous NO synthase (NOS) inhibitor. This could solve the L-arginine paradox namely that L-arginine improves NO-mediated vascular function in vivo, although its baseline plasma concentration is about 25- to 30-fold higher than the Michaelis-Menten constant Km of the isolated, purified eNOS in vitro. Recent findings suggest that large, prospective, randomized clinical trials might be needed to identify those patients who are the most likely to benefit from L-arginine. Testing patients for ADMA and L-arginine plasma levels for calculating the L-arginine/ADMA ratio might be an adequate strategy.

Topics: Animals; Arginine; Dietary Supplements; Humans; Myocardial Infarction; Nitric Oxide Synthase Type III

 Exposure to tobacco smoke is associated with a higher cardiovascular risk, especially in patients with coronary artery disease (CAD). .  The aim of the study was to evaluate the effect of active and passive tobacco smoking on the activity of endothelial markers in advanced atherosclerosis..  We studied 181 consecutive patients with advanced CAD (53 women and 128 men) aged 60 ±8 years, including 102 active self‑declared smokers (56.3%). We determined plasma asymmetric dimethylarginine (ADMA), thrombomodulin (TM), and plasminogen activator inhibitor‑1 (PAI‑1) levels, along with serum cotinine concentrations as a marker of tobacco smoking. .  Plasma ADMA levels were higher in active smokers compared with nonsmokers (0.60 ±0.09 μmol/l vs. 0.49 ±0.08 μmol/l, P <0.001). There were similar intergroup differences in TM (4.60 ±2.11 ng/ml vs. 3.0 ±1.7 ng/ml, P <0.0001) and PAI‑1 levels (30.3 ±12.4 ng/ml vs. 23.6 ±11.3 ng/ml, P <0.0001). We observed positive correlations between cotinine and ADMA (r = 0.71, P <0.0001), TM (r = 0.53, P <0.0001), and PAI‑1 (r = 0.58, P <0.0001). In 21 patients (26.6%) who declared to be nonsmokers, cotinine levels (mean, 6.30 ±22.5 ng/ml) significantly correlated with ADMA, TM, and PAI‑1 (all P <0.001). A multivariate regression analysis showed that cotinine was an independent predictor of ADMA, TM, and PAI‑1 in the whole patient group. .  Despite long‑lasting endothelial injury in advanced CAD, continued cigarette smoking is able to further enhance endothelial damage by increasing ADMA levels and resultant inhibition of fibrinolysis.

Topics: Arginine; Biomarkers; Comorbidity; Coronary Artery Disease; Cotinine; Disease Progression; Endothelium, Vascular; Female; Humans; Male; Middle Aged; Multivariate Analysis; Myocardial Infarction; Plasminogen Activator Inhibitor 1; Regression Analysis; Smoking; Thrombomodulin; Tobacco Smoke Pollution

Mechanisms linking chronic kidney disease (CKD) and adverse outcomes in acute coronary syndromes (ACS) are not fully understood. Among potential key players, reduced nitric oxide (NO) synthesis due to its endogenous inhibitors, asymmetric (ADMA) and symmetric (SDMA) dimethylarginine could be involved. We measured plasma concentration of arginine, ADMA and SDMA and investigated their relationship with CKD and long-term outcome in non-ST-elevation myocardial infarction (NSTEMI).. We prospectively measured arginine, ADMA, and SDMA at hospital admission in 104 NSTEMI patients. CKD was defined as an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2). We considered a primary end point of combined cardiac death and re-infarction at a median follow-up of 21 months. In CKD (n = 33) and no-CKD (n = 71) patients, arginine and ADMA were similar, whereas SDMA was significantly higher in CKD patients (0.65±0.23 vs. 0.42±0.12 µmol/L; P<0.0001). Twenty-four (23%) patients had an adverse cardiac event during follow-up: 12 (36%) were CKD and 12 (17%) no-CKD patients (P = 0.02). When study population was stratified according to arginine, ADMA and SDMA median values, only SDMA (median 0.46 µmol/L) was associated with the primary end-point (P = 0.0016). In models adjusted for age, hemoglobin and left ventricular ejection fraction, the hazard ratio (HR) for CKD and SDMA were high (HR 2.93, interquartile range [IQR] 1.15-7.53; P = 0.02 and HR 6.80, IQR 2.09-22.2; P = 0.001, respectively) but, after mutual adjustment, only SDMA remained significantly associated with the primary end point (HR 5.73, IQR 1.55-21.2; P = 0.009).. In NSTEMI patients, elevated SDMA plasma levels are associated with CKD and worse long-term prognosis.

Topics: Aged; Arginine; Endpoint Determination; Female; Follow-Up Studies; Humans; Kaplan-Meier Estimate; Kidney Function Tests; Male; Middle Aged; Myocardial Infarction; Nitric Oxide; Proportional Hazards Models; Renal Insufficiency, Chronic; Treatment Outcome; Ultrasonography

Asymmetric dimethylarginine (ADMA) and N(G) monomethyl-L-arginine (L-NMMA) are endogenous inhibitors of nitric oxide synthases (NOS) and their local concentration is determined by the activity of dimethylarginine dimethylaminohydrolases (DDAHs). The current study in male Wistar rats was designed to immunolocalise DDAH I and II in relation to NOS and to investigate changes in distribution, activity and ADMA content in the acute period following myocardial infarction (MI) resulting from coronary artery ligation. Seven days after the coronary artery ligation, L-Arg and methylated arginine content, as well as DDAH activity were determined in homogenates of left ventricular (LV) infarct and border. The distribution of immunoreactive DDAH I, DDAH II, eNOS and iNOS were determined in sections of LV. In healthy hearts, DDAH I was absent, however, DDAH II was localized to endothelium and endocardium with a similar distribution to that of eNOS. Following MI, LV DDAH activity was increased (to 210+/-19% of control, P<0.05). Both DDAH I and DDAH II proteins were detected in peri-infarct cardiomyocytes, while DDAH II immunoreactivity was additionally localized to infiltrating inflammatory cells and blood vessels in the healing infarct. Both plasma and LV concentrations of the DDAH substrate, ADMA, were increased post-MI, although the ratio of Arg:ADMA was retained in the LV post-MI relative to sham operated controls. In conclusion, DDAH II has a distribution similar to eNOS in healthy myocardium. The increased levels and activity of DDAH I and DDAH II enzymes following myocardial infarction suggest a potential role for them in local protection of NOS enzymes from inhibition by methylated arginines during infarct healing.

Topics: Amidohydrolases; Animals; Aorta; Arginine; Disease Models, Animal; Endocardium; Heart Ventricles; Male; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Protein-Arginine N-Methyltransferases; Rats; Rats, Wistar

Patients with diabetes mellitus (DM) have been shown to have higher levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of endothelial nitric oxide (NO) synthase. Higher plasma levels of ADMA have been implicated in the pathogenesis of endothelial dysfunction and atherosclerosis by lowering NO levels. High baseline plasma levels of ADMA in patients with DM have been shown to predict diabetes related complications. However, there are limited data on the prognostic significance of baseline ADMA levels in patients with established DM.. The present study investigated the long-term prognostic significance of baseline plasma ADMA levels in a well-characterized cohort of 170 high-risk diabetic men with known or suspected coronary artery disease who were referred for coronary angiography. All patients were followed prospectively for the development of vascular outcomes, including all-cause mortality.. After controlling for a variety of baseline variables (including established biomarkers such as hs-CRP and fibrinogen), plasma ADMA levels (analyzed as the upper tertile of baseline values compared with the lower two tertiles) were a strong and independent predictor of all-cause mortality (HR 2.63, 95% CI 1.13-6.11, p=0.0247) when using a Cox proportional hazards model. In addition, baseline ADMA values were also an independent predictor of the composite outcome of all-cause mortality or MI (fatal or non-fatal) (HR 2.44, 95% CI 1.26-4.72, p=0.0079), as well as the composite outcome of all-cause mortality, MI (fatal or nonfatal), or stroke (HR 2.00, 95% CI 1.10-3.62, p=0.0232).. These data demonstrate that elevated baseline levels of ADMA are a strong and independent predictor of cardiovascular outcomes (including all-cause mortality) in patients with DM.

Topics: Aged; Arginine; Coronary Angiography; Coronary Disease; Diabetes Complications; Humans; Male; Myocardial Infarction; Prognosis; Proportional Hazards Models; Stroke

Topics: Arginine; Dietary Supplements; Humans; Myocardial Infarction; Nitric Oxide Synthase