dimethylarginine and Kidney-Failure--Chronic

Asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is increasingly recognized as a putative biomarker in cardiovascular and renal disease. Elevated plasma levels of ADMA are the consequence of increased synthesis, reduced renal clearance or reduced enzymatic degradation. Based upon the metabolic fate the highest plasma concentrations of ADMA have been reported in patients with renal failure in whom this molecule accumulates. However, the range of published ADMA levels in patients with chronic renal failure as well as in patients with end-stage renal failure undergoing maintenance hemodialysis, peritoneal dialysis or kidney transplant recipients is widely scattered and overlaps with the levels reported in healthy individuals. This wide distribution can in part be explained by different bioanalytical techniques and the lack of standardization of such assays. This review summarizes available literature on ADMA in patients with kidney disease and stresses the urgent need for a consensus regarding reference values for different analytical methods in order to appreciate the prognostic significance of elevated ADMA levels. At present, one cannot advocate this molecule for risk assessment or individual patient prognosis in the clinical work-up of patients with renal impairment.

Topics: Adult; Aged; Animals; Arginine; Biomarkers; Female; Humans; Kidney Diseases; Kidney Failure, Chronic; Male; Middle Aged; Models, Biological; Nephrology; Reference Values; Reproducibility of Results

Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, is formed by methylation of arginine residues in proteins and released after proteolysis. In this reaction, S-adenosylmethionine is methyldonor and S-adenosylhomocysteine the demethylated product. ADMA and homocysteine are thus biochemically linked. Both plasma homocysteine and ADMA concentrations are increased in patients with renal dysfunction, probably as a result of an impairment in their metabolic, but not urinary, clearance. Hyperhomocysteinemia has been associated with an increased risk of cardiovascular disease in end-stage renal disease, especially in patients without malnutrition and inflammation. Also, plasma ADMA levels have been associated with cardiovascular disease in renal failure patients. Both homocysteine and ADMA are thought to mediate their adverse vascular effects by impairing endothelial, nitric oxide-dependent function resulting in decreased vasodilatation, increased smooth muscle cell proliferation, platelet dysfunction and increased monocyte adhesion. At the same time, it has been shown that the correlation between plasma ADMA and homocysteine is weak and that, in renal patients, the association of plasma ADMA carotid intima-media thickness, cardiovascular events and overall mortality is independent of homocysteine. This indicates that the negative vascular effects of ADMA and homocysteine have a different etiology. Treatment with folic acid substantially lowers homocysteine, but not ADMA concentration. So far, homocysteine-lowering therapy has not been very successful in decreasing cardiovascular disease. In patients with renal failure, ADMA reduction may be an interesting new goal in the prevention of cardiovascular disease.

Topics: Arginine; Homocysteine; Humans; Kidney Failure, Chronic; Vascular Diseases

Decreased nitric oxide (NO) production and/or impaired NO bioavailability may occur in patients with chronic kidney disease (CKD), and could contribute to the elevation of blood pressure, cardiovascular disease (CVD) and the progression of renal injury in these patients. However, the underlying molecular mechanisms for reduced NO action in patients with CKD remains to be elucidated. Asymmetric dimethylarginine (ADMA) is a naturally occurring L-arginine analogue found in plasma and various types of tissues, acting as an endogenous NO synthase inhibitor in vivo. Further, plasma level of ADMA is elevated in patients with CKD and found to be a strong biomarker or predictor for future cardiovascular events. In addition, plasma level of ADMA could predict the progression of renal injury in these patients as well. These findings suggest that elevation of ADMA may be a missing link between CVD and CKD. In this review, we discuss the molecular mechanisms for the elevation of ADMA and its pathophysiological role for CVD in high-risk patients, especially focusing on patients with CKD.

Topics: Arginine; Cardiovascular Diseases; Humans; Kidney Failure, Chronic

Patients with chronic kidney disease and patients undergoing hemodialysis treatment show a sustained overactivity of the sympathetic nervous system, which originates from signals arising in the failing kidneys and traveling via afferent renal nerves to cardiovascular centers in the brainstem. Additional important factors are increased levels of angiotensin II and asymmetrical dimethylarginine. The sympathetic overactivity contributes to hypertension and cardiovascular morbidity and mortality in that patient population. Sympathetic overactivity can be reduced by adrenergic receptor blockers, centrally acting sympathicolytic drugs such as moxonidine and rilmenidine, angiotensin-converting enzyme inhibition, and angiotensin II type 1 receptor antagonists. Daily short hemodialysis and long nocturnal hemodialysis may reduce the elevated sympathetic activity, possibly because of an increased clearance of asymmetrical dimethylarginine, an endogenous nitric oxide synthase inhibitor. Prospective trials examining the potential impact of both beta-blockers and centrally acting sympatholytic drugs on cardiovascular mortality in chronic kidney disease and hemodialysis patients are very much needed.

Topics: Adrenergic alpha-Agonists; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Arginine; Brain Stem; Humans; Hyperkinesis; Hypertension, Renal; Imidazoles; Kidney Failure, Chronic; Nitric Oxide Synthase; Oxazoles; Receptor, Angiotensin, Type 1; Renal Dialysis; Rilmenidine; Sympathetic Nervous System; Sympatholytics

Although the high risk for cardiovascular events in patients with end-stage renal disease (ESRD) is well known, recent data provide compelling evidence that even mild to moderate kidney disease is an important and independent risk factor for cardiac events. This increased risk does not seem to be explained by traditional risk factors as defined by the Framingham cohort. The examination of nontraditional risk factors has resulted in the identification of, among others, oxidant stress, hyperhomocystinemia, carbamylation, nitric oxide synthase inhibitors, and abnormal lipoproteins as potential pathways to explain the accelerated atherosclerosis in patients with kidney disease. Well-designed clinical trials should lead to the clarification of the relative importance of these factors in the pathogenesis of atherosclerotic disease.

Topics: Arginine; Cardiovascular Diseases; Humans; Hyperhomocysteinemia; Inflammation; Kidney Diseases; Kidney Failure, Chronic; Kidney Transplantation; Lipoproteins; Lipoproteins, LDL; Nitric Oxide Synthase; Oxidative Stress; Proteinuria; Renal Dialysis; Risk Factors

Haemodialysis (HD) is associated with the acute loss through the dialysis membrane of biochemical factors either enhancing [folic acid (F)] or impairing [asymmetric dimethylarginine (ADMA)] arterial function. Changes in these opposing factors might explain the absence of significant modifications in arterial function during HD. We speculated that intra-HD, instead of pre-HD, F administration would provide beneficial effects on arterial wave reflections and endothelial function by preventing HD-induced F loss.. Arterial wave reflections [augmentation index (AIx), pulse-wave analysis], endothelium-dependent vasodilation (salbutamol-mediated changes in AIx) and plasma concentrations of F and ADMA were measured pre-HD and end-HD in 10 patients (age 67.7 +/- 10.3 years). Each subject received F 5 mg either pre-HD or intra-HD in two separate studies 2-4 weeks apart, in an open-label randomized cross-over trial.. Pre-HD F administration did not prevent significant reductions in F during HD (end-HD vs. pre-HD, -865 +/- 465 nmol l(-1), P < 0.001), but no significant changes in AIx (+1.4 +/- 5.7%) or salbutamol-mediated AIx modifications (+0.4 +/- 5.5%) were observed. By contrast, intra-HD F administration was associated with significant increases in F (+298 +/- 283 nmol l(-1), P = 0.010) and a significant reduction of AIx (-4.7 +/- 7.2%, P = 0.013), but no effects on salbutamol-mediated AIx changes (+1.5 +/- 4.4%). There was a trend towards greater HD-induced reductions in plasma ADMA concentrations with intra-HD F administration (P = 0.066).. Intra-HD F administration reduces arterial wave reflections but not endothelial function during HD. Given the prognostic significance of arterial wave reflections in HD patients, the timing of F administration is important in the design of interventional trials in this cohort.

Topics: Aged; Albuterol; Arginine; Cross-Over Studies; Drug Administration Schedule; Endothelium, Vascular; Female; Folic Acid; Humans; Kidney Failure, Chronic; Male; Middle Aged; Radial Artery; Renal Dialysis; Statistics, Nonparametric; Vasodilator Agents

Cardiovascular disease is the main cause of mortality in chronic kidney disease patients. Moreover, uremic patients are in a pro-oxidant state and show an increase in asymmetric dimethylarginine (ADMA) levels due to inhibition of the enzyme dimethylarginine dimethylaminohydrolase (DDAH). Asymmetric dimethylarginine per se seems responsible for a 52% increase in the risk of death and for a 34% increase in the risk of cardiovascular events in dialysis patients. N-acetylcysteine (NAC) is a thiol molecule that has direct and indirect antioxidant effects which decrease reactive oxidant species and increase the bioavailability of the DDAH enzyme. The aim of the current study was to determine the effect of intravenous NAC on plasma ADMA level when administered during hemodialysis in end-stage renal disease (ESRD) patients.. 40 patients with ESRD were randomized to receive a 4-hour intravenous infusion of NAC or placebo during a 4-hour hemodialysis session. There were 3 diabetic patients (15%) in the treatment group and 6 patients in the control group. Plasma ADMA levels were measured before and immediately after hemodialysis. Hemodynamic parameters, including pulse pressure, were also measured. The paired t-test was used to compare the difference of ADMA levels before and after hemodialysis in each group, while the independent t-test was used to compare the difference of ADMA levels between the groups.. Compared with the pre-dialysis condition, there was a decrease of ADMA level in the control group (1.1253 +/- 0.1797 microM to 0.8676 +/- 0.1449 microM) (p < 0.001), and in the NAC group (1.1522 +/- 0.1737 microM to 0.7844 +/- 0.1586 microM) (p < 0.001). Compared with hemodialysis alone, NAC had a greater lowering effect on the ADMA level (21.3 vs. 31.9%, p < 0.05).. N-acetylcysteine (NAC) administered intravenously during hemodialysis reduced asymmetric dimethylarginine (ADMA) levels more significantly than hemodialysis alone.

Topics: Acetylcysteine; Adult; Aged; Arginine; Biomarkers; Double-Blind Method; Enzyme-Linked Immunosorbent Assay; Female; Follow-Up Studies; Free Radical Scavengers; Humans; Infusions, Intravenous; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis; Treatment Outcome

We have reported that indoxyl sulfate (IS), a uremic toxin, accelerates proximal tubular cell senescence. Asymmetric dimethylarginine (ADMA), an inhibitor of nitric oxide synthase, has been reported to induce endothelial cell senescence. This study aimed to determine whether IS induces endothelial cell senescence in comparison with ADMA, and to investigate its molecular mechanism.. Human umbilical vein endothelial cells (HUVECs) were incubated with IS (250 μM) and/or ADMA (10 μM). These concentrations were comparable with their mean serum levels in hemodialysis patients. Cell senescence was evaluated by measuring senescence-associated beta-galactosidase (SA-β-gal) activity. N-acetylcysteine, an antioxidant, and pifithrin alpha p-nitro, a p53 inhibitor, were used to determine the role of reactive oxygen species (ROS) and p53 in the induction of cell senescence.. Both IS and ADMA significantly increased SA-β-gal activity in HUVECs. Further, some additional increase in SA-β-gal activity was observed when IS and ADMA were co-incubated. Preincubation of N-acetylcysteine or pifithrin alpha p-nitro significantly inhibited SA-β-gal activity induced by IS and ADMA in HUVECs. Thus, both IS and ADMA induced endothelial senescence through ROS and p53.. IS induces endothelial cell senescence by increasing ROS production and p53 activity, like ADMA.

Topics: Arginine; Cellular Senescence; Enzyme Inhibitors; Human Umbilical Vein Endothelial Cells; Humans; Indican; Kidney Failure, Chronic; Nitric Oxide Synthase; Reactive Oxygen Species; Tumor Suppressor Protein p53

The study focuses on the mechanisms of endothelial dysfunction in the uremic milieu. Subcutaneous resistance arteries from 35 end-stage renal disease (ESRD) patients and 28 matched controls were studied ex-vivo. Basal and receptor-dependent effects of endothelium-derived factors, expression of endothelial NO synthase (eNOS), prerequisites for myoendothelial gap junctions (MEGJ), and associations between endothelium-dependent responses and plasma levels of endothelial dysfunction markers were assessed. The contribution of endothelium-derived hyperpolarizing factor (EDHF) to endothelium-dependent relaxation was impaired in uremic arteries after stimulation with bradykinin, but not acetylcholine, reflecting the agonist-specific differences. Diminished vasodilator influences of the endothelium on basal tone and enhanced plasma levels of asymmetrical dimethyl L-arginine (ADMA) suggest impairment in NO-mediated regulation of uremic arteries. eNOS expression and contribution of MEGJs to EDHF type responses were unaltered. Plasma levels of ADMA were negatively associated with endothelium-dependent responses in uremic arteries. Preserved responses of smooth muscle to pinacidil and NO-donor indicate alterations within the endothelium and tolerance of vasodilator mechanisms to the uremic retention products at the level of smooth muscle. We conclude that both EDHF and NO pathways that control resistance artery tone are impaired in the uremic milieu. For the first time, we validate the alterations in EDHF type responses linked to kinin receptors in ESRD patients. The association between plasma ADMA concentrations and endothelial function in uremic resistance vasculature may have diagnostic and future therapeutic implications.

Topics: Adult; Aged; Arginine; Arteries; Biological Factors; Bradykinin; Endothelium, Vascular; Female; Gap Junctions; Humans; Kidney Failure, Chronic; Male; Middle Aged; Nitric Oxide Synthase Type III; Vasodilator Agents

Nε-homocysteinyl-lysine (Nε-Hcy-Lys), a product of proteolysis of Nε-homocysteinylated proteins, has been discovered recently. We sought to investigate the presence of Nε-Hcy-Lys in patients on long-term hemodialysis (HD) and its association with markers involved in atherosclerotic vascular disease.. We studied 86 patients on long-term (median, 45 months) HD and 95 apparently healthy controls. Nε-Hcy-Lys and total homocysteine (tHcy) were assayed using high-performance liquid chromatography. Paraoxonase 1 (PON1), asymmetric dimethylarginine (ADMA), folate, 8-isoprostaglandin F2α(8-iso-PGF2α), plasminogen activator inhibitor-1 (PAI-1), C-reactive protein (CRP), together with antibodies against Nε-homocysteinylated albumin and hemoglobin, were also measured.. Nε-Hcy-Lys was detected in 15 HD patients (17.4%). Those patients had 3.1-times lower PON1 (p<0.0001), 20% higher ADMA (p<0.0001), 30% higher PAI-1 (p<0.0001), 10% lower total cholesterol (p=0.001) and LDL-cholesterol (p<0.0001), together with 20% lower triglycerides (p<0.0001) compared with subjects without measurable Nε-Hcy-Lys. Nε-Hcy-Lys levels correlated with PON1 (r=-0.62, p<0.0001), ADMA (r=0.58, p<0.0001) and PAI-1 (r=0.59, p<0.0001). Folic acid supplementation, tHcy, folate, autoimmune response to Nε-Hcy-proteins, and oxidative stress were not associated with the presence of Nε-Hcy-Lys. PON1 is the only independent predictor of the presence of Nε-Hcy-Lys in HD patients. None of controls had measurable Nε-Hcy-Lys in serum.. The presence of Nε-Hcy-Lys in HD patients is relatively infrequent and associated with lipid profile, endothelial dysfunction and impaired fibrinolysis, regardless of tHcy and folate levels.

Topics: Aged; Antibodies; Arginine; Atherosclerosis; Biomarkers; Dipeptides; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis

To investigate the roles of insulin, glucose, and oxidative stress on plasma asymmetric and symmetric dimethylarginine (ADMA, SDMA) levels in complicated diabetes, we studied patients with type 1 diabetes (T1D; n = 20), T1D + end-stage renal disease under hemodialysis (T1D + ESRD; n = 12), T1D + ESRD who received kidney transplant (KD; n = 16), and T1D + ESRD who received kidney-pancreas transplant (KP; n = 20) and healthy controls (n = 50). Levels of ADMA, SDMA, and free and total malondialdehyde (MDA) were increased in all patients, with the highest rises for SDMA and free MDA in T1D+ESRD. In KP, the normalized glycemia contributes to the recovery of ADMA, SDMA, and MDA levels toward normal values. From the covariance analyses, both glucose and insulin relate significantly to ADMA in T1D + ESRD (beta = +0.004, beta = -0.038, respectively) and in KP (beta = +0.032, beta = +0.032, respectively). Creatinine clearance and insulin relate to SDMA in all patient groups (beta = -0.006). Our results provide evidence for the effect of kidney-pancreas transplant on the recovery of ADMA, SDMA, and indexes of oxidative stress toward normal values. Only free MDA allows one to discriminate the magnitude of the oxidative status, as increased total MDA could also be attributable to a reduced renal function.

Topics: Adult; Arginine; Biomarkers; Blood Glucose; Cross-Sectional Studies; Diabetes Mellitus, Type 1; Female; Humans; Insulin; Kidney Failure, Chronic; Kidney Transplantation; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Recovery of Function; Renal Dialysis

To investigate the correlation between concentrations of asymmetric dimethylarginine (ADMA) and neopterin (NP) as potential risk factors for cardiovascular diseases in chronic renal failure patients.. In this study, 33 patients with renal failure before and after haemodialysis were compared with healthy control subjects. Serum ADMA and NP levels were measured using high performance liquid chromatography (HPLC).. When ADMA and NP concentrations in renal failure patients were compared before and after dialysis, before dialysis ADMA and NP concentrations were higher than those in the control group. However, ADMA and NP levels showed a falling mean and clear after dialysis. While there is no correlation between ADMA and NP levels before dialysis, there is a mean and positive correlation between ADMA and NP levels after dialysis.. Potential risk factors for cardiovascular diseases include high concentrations of both ADMA and NP levels in chronic renal failure patients. A correlation mean between ADMA and NP levels after dialysis was found, but no correlation between ADMA and NP levels before haemodialysis was discovered. These can be evaluated as two different risk factors independent from each other.

Topics: Arginine; Cardiovascular Diseases; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Neopterin; Renal Dialysis; Risk Factors

To investigate whether circulating asymmetric dimethylarginine (ADMA) levels are predictive of cardiovascular events, decline in glomerular filtration rate (GFR), end-stage renal disease (ESRD), and all-cause mortality in type 1 diabetic patients.. We performed a prospective observational follow-up study including 397 type 1 diabetic patients with overt diabetic nephropathy (243 men aged 42.1 +/- 10.5 years, GFR 76 +/- 34 ml/min per 1.73 m(2)) and a control group of 175 patients with longstanding type 1 diabetes and persistent normoalbuminuria (104 men aged 42.7 +/- 9.7 years, duration of diabetes 27.7 +/- 8.3 years). Patients were followed for a median 11.3 years (range 0.0-12.9) with yearly measurements of GFR ((51)Cr-EDTA plasma clearance) in patients with diabetic nephropathy. Endpoints were fatal and nonfatal cardiovascular disease (CVD), decline in GFR, ESRD, and all-cause mortality.. Among patients with diabetic nephropathy, 37 patients (19.4%) with ADMA levels below the median, compared with 79 patients (43.4%) above the median, suffered a major cardiovascular event during the follow-up period (P < 0.001). This effect persisted after adjustment for conventional CVD risk factors including baseline GFR (adjusted hazard ratio [HR] for elevated ADMA 2.05 [95% CI 1.31-3.20], P = 0.002). Furthermore, elevated ADMA levels predicted an increased rate of decline in GFR, development of ESRD, and all-cause mortality (P < 0.001). After adjustment for well-known progression promoters, including baseline GFR, the HR (adjusted) was 1.85 (95% CI 0.99-3.46, P = 0.055) for ESRD comparing upper and lower median ADMA levels.. Plasma ADMA levels predict fatal and nonfatal cardiovascular events in patients with type 1 diabetic nephropathy. Furthermore, increased ADMA levels tend to contribute to increased risk of progressive diabetic kidney disease.

Topics: Adult; Albuminuria; Arginine; Biomarkers; Cardiovascular Diseases; Diabetes Mellitus, Type 1; Diabetic Angiopathies; Diabetic Nephropathies; Female; Glomerular Filtration Rate; Glycated Hemoglobin; Humans; Kidney Failure, Chronic; Male; Middle Aged

In this study, we aimed to investigate the activities of paraoxonase-1 (PON1) and nitric oxide synthase (NOS) and the levels of asymmetric dimethylarginine (ADMA), nitric oxide (NO), oxidized low-density lipoprotein (oxLDL), ceruloplasmin (CP), thiobarbituric acid-reactive substances (TBARS), malondialdehyde (MDA), 4-hydroxynonenal (HNE) and lipids in serum of patients with end-stage renal disease (ESRD) having continuous ambulatory peritoneal dialysis (CAPD) treatment and controls living in the Antalya region, Turkey.. Fifty-three patients with ESRD were enrolled in this study and were treated by CAPD. As the control group (n=32), subjects with normal renal function were included.. Serum PON1 activity and high-density lipoprotein-cholesterol (HDL-C) levels were decreased in ESRD patients whereas ADMA, NO, oxLDL, CP, TBARS, MDA and HNE levels and NOS activity were increased with regard to control group. In CAPD patients, ADMA positively correlated with NO, CP, oxLDL, TBARS and MDA levels whereas negatively correlated with PON1 activity. On multiple logistic regression analysis, risk factors associated with ESRD included CP, TBARS, triglycerides (TG) and very low-density lipoprotein-cholesterol (VLDL-C) levels.. Our data have demonstrated that ESRD patients on CAPD treatment exhibit increased lipid peroxidation reactions and decreased antioxidant protection. The assay of serum HNE and MDA may be useful to evaluate the individual accumulation of these toxic aldehydes to test the efficiency of new dialysis strategies in removing them.

Topics: Arginine; Aryldialkylphosphatase; Biomarkers; Female; Humans; Kidney Failure, Chronic; Lipid Peroxidation; Lipids; Lipoproteins; Lipoproteins, LDL; Male; Nitric Oxide; Nitric Oxide Synthase; Peritoneal Dialysis, Continuous Ambulatory; Reference Values; Thiobarbituric Acid Reactive Substances

Topics: Arginine; Case-Control Studies; Chromatography, High Pressure Liquid; Enzyme-Linked Immunosorbent Assay; Humans; Kidney Failure, Chronic; Reproducibility of Results; Sensitivity and Specificity

Patients with Type 2 diabetes mellitus (T2DM) and micro- and macroalbuminuria are at increased cardiovascular risk. The endogenous nitric oxide synthase inhibitor asymmetrical dimethylarginine (ADMA) is increased in renal failure and could promote atherosclerosis. To determine the relationship between ADMA, renal albumin excretion rate (AER) and cardiovascular risk, we studied 103 T2DM patients.. ADMA, symmetrical dimethylarginine (SDMA) and L-arginine were determined by high-performance liquid chromatography in plasma from 36 normo-, 40 micro- and 27 macroalbuminuric patients with T2DM (age 64 +/- 11 years; 38 women) who had comparable age, sex and metabolic parameters. Forty-six patients had macrovascular disease (MVD).. ADMA was significantly increased in patients with micro- and macroalbuminuria [median 0.61 (interquartile range 0.55-0.70) micromol/l and 0.62 (0.50-0.79) micromol/l, respectively] compared with those with normoalbuminuria [0.55 (0.48-0.63) micromol/l; both P < 0.05]. SDMA was elevated in micro- and macroalbuminuria [0.57 (0.42-0.80) micromol/l and 0.64 (0.50-0.96) micromol/l] compared with normoalbuminuric subjects [0.44 (0.37-0.53) micromol/l; both P < 0.01]. Patients with increased AER and MVD had higher ADMA and SDMA compared with those without MVD (both P < 0.001). L-arginine was comparable between all groups. ADMA correlated significantly with high-sensitivity C-reactive protein (hsCRP) and glomerular filtration rate (GFR) but not with the extent of albumin excretion, body mass index, fasting glucose, HbA(1c) or plasma lipids.. Increased ADMA in T2DM patients with albuminuria is linked to cardiovascular disease and is associated with renal dysfunction and subclinical inflammation.

Topics: Aged; Albuminuria; Arginine; Atherosclerosis; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Diabetic Nephropathies; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged

Cardiovascular events are accelerated in chronic kidney disease (CKD). Although deranged nitric oxide (NO) pathways and asymmetric dimethylarginine (ADMA) cause endothelial dysfunction, no direct evidence for coronary artery endothelial dysfunction in CKD has been documented. CKD was induced in male dogs by heminephrectomy (1/2Nx) or five-sixths nephrectomy (5/6Nx). After 4 wk, renal ablation reduced GFR (control 76 [54 to 85]; 1/2Nx 38 [29 to 47]; 5/6Nx 15 [12 to 46] ml/min) and elevated plasma ADMA (control 1.88 [1.68 to 2.54]; 1/2Nx 2.51 [2.11 to 3.55]; 5/6Nx 3.84 [2.16 to 3.95] micromol/L). Coronary circulatory responses to acetylcholine revealed marked increases in coronary blood flow in control group (83 +/- 17% increment) but blunted responses in 1/2Nx (34 +/- 8% increment) and 5/6Nx (20 +/- 4% increment). The acetylcholine-induced changes in epicardial arteriolar diameter, using needle-lens probe charge-coupled device videomicroscopy, showed similar results. The responsiveness to sodium nitroprusside did not differ among three groups. Plasma nitrite/nitrate levels decreased in 1/2Nx and 5/6Nx, and the mRNA expressions of dimethylarginine dimethylaminohydrolase-II (DDAH-II), ADMA-degrading enzyme, and endothelial NO synthase (eNOS) in coronary arteries were downregulated in 1/2Nx and 5/6Nx. Finally, 4-wk treatment with all-trans retinoic acid restored the impaired endothelium-dependent vasodilation and reversed the expression of eNOS but not DDAH-II. Coronary endothelial function is impaired in the early stage of CKD. The dysfunction is attributed to the downregulation of eNOS and/or DDAH-II in coronary arteries. Furthermore, the manipulation of NO pathways may constitute a therapeutic strategy for the prevention of coronary dysfunction in CKD.

Topics: Acetylcholine; Amidohydrolases; Animals; Arginine; Coronary Circulation; Disease Models, Animal; Dogs; Endothelium-Dependent Relaxing Factors; Endothelium, Vascular; Glomerular Filtration Rate; Kidney Failure, Chronic; Male; Microscopy, Video; Nitric Oxide; Nitric Oxide Synthase Type III; Nitroprusside; Tretinoin; Vasodilation; Vasodilator Agents

The arginine derivatives asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) interfere with endothelial nitric oxide synthesis. Plasma ADMA and SDMA have been shown to be risk factors for cardiovascular disease and/or kidney function deterioration in a variety of patient populations.. We developed a method to quantitatively measure arginine, ADMA, and SDMA using HPLC-tandem mass spectrometry. 13C6-L-Arginine was used as the internal standard, while the derivatives were separated on a silica column in less than 14 min. Plasma levels of ADMA, SDMA, and arginine were measured in children with stage II or III chronic kidney disease (CKD) and age- and gender-matched siblings.. The chromatography exhibited no observable ion suppression in the patient specimens tested. There was no apparent carryover for any of the analytes. The assay was linear over 0.32-2.29, 0.23-4.43, and 1.00-303.89 micromol/L for ADMA, SDMA, and arginine, respectively. Plasma ADMA, SDMA, and arginine (mean+/-SD) were 1.10+/-0.35, 2.06+/-1.11, and 57.93+/-22.10 mumol/L for children with CKD, and 0.78+/-0.16, 0.71+/-0.23, and 65.29+/-21.30 micromol/L for the healthy siblings.. The method exhibited no observable ion suppression in the patient specimens tested and has an acceptably short analytical cycle time. Children with CKD had higher levels of ADMA and SDMA than the healthy siblings.

Topics: Adolescent; Arginine; Biomarkers; Case-Control Studies; Child; Chromatography, High Pressure Liquid; Female; Humans; Kidney Failure, Chronic; Male; Reproducibility of Results; Sensitivity and Specificity; Siblings; Tandem Mass Spectrometry; Time Factors

To assess the acute effects of haemodialysis (HD) on biochemical factors modulating endothelial function.. Academic medical centre.. Forty patients (age 63.5 +/- 2.2 years, mean +/- SEM) undergoing HD.. Folic acid (F), homocysteine (tHcy), asymmetric dimethylarginine (ADMA), high-sensitivity C-reactive protein (CRP) and malondialdehyde (MDA) were measured pre-HD, 1 h after commencing HD and within the last hour of HD (end-HD). Endothelium-dependent and -independent vasodilatation were measured by applanation tonometry (changes in augmentation index, AIx, postinhaled salbutamol and postsublingual nitroglycerin) in conjunction with biochemical measurements.. Marked reductions in serum F (616 +/- 73 vs. 273 +/- 30 nmol L(-1), P < 0.001), tHcy (16.3 +/- 0.7 vs. 11.2 +/- 0.5 micromol L(-1), P < 0.001) and ADMA (0.64 +/- 0.02 vs. 0.47 +/- 0.02 micromol L(-1), P < 0.001) occurred end-HD, whereas CRP and MDA levels did not significantly change. There was no significant change in endothelium-dependent vasodilatation, whereas endothelium-independent vasodilatation improved end-HD (-23.1 +/- 1.9 vs. -17.3 +/- 1.3%, P = 0.018). Regression analysis showed that both higher ADMA (P = 0.029) and lower F levels (P = 0.040) end-HD were determinants of reduced endothelium-dependent vasodilatation end-HD (R(2) = 0.23).. HD is associated with significant reductions in F, tHcy and ADMA serum concentrations. The lack of significant effects of HD on endothelium-dependent vasodilatation could be secondary to the concomitant loss of factors either enhancing (F) or impairing (ADMA) endothelial function.

Topics: Arginine; Blood Pressure; C-Reactive Protein; Endothelium, Vascular; Female; Folic Acid; Heart Rate; Homocysteine; Humans; Kidney Failure, Chronic; Male; Malondialdehyde; Middle Aged; Renal Dialysis; Vasodilation

Symmetrical dimethylarginine (SDMA) is the structural isomer of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine. Whereas the major route of asymmetric dimethylarginine elimination is the hydrolytic degradation by dimethylarginine dimethylaminohydrolase, SDMA is eliminated by renal excretion. SDMA does not directly inhibit NOS but is a competitor of arginine transport. This study showed for the first time that measurement of SDMA can be a marker of estimated GFR and extent of coronary artery disease (CAD). In 97 patients with CAD, SDMA was a marker of estimated GFR. On multiple regression analysis of the CAD parameter stenosis score, SDMA was the only parameter retained. In addition, endothelial cells from the third passage were cultured in medium that contained 70 micromol/L arginine and was incubated for 24 h in the presence of various concentration of SDMA (0, 2, 5, 10, and 100 micromol/L). The levels of nitrate and nitrite in conditioned media, the protein expression of NOS, and the content of reactive oxygen species in endothelial cells were determined. SDMA inhibited dose dependently the NO synthesis in intact endothelial cells, whereas it had no effect on protein expression of NOS. This effect was associated with an increase in reactive oxygen species. Co-incubation with L-arginine but not D-arginine reversed the effect of SDMA on NOS pathway. Our data suggest that SDMA reduced the endothelial NO synthesis, probably by limiting L-arginine supply to NOS. It is concluded that SDMA might be a useful parameter for detecting patients in very early stages of chronic kidney disease and for determining their risk for developing cardiovascular disease.

Topics: Aged; Arginine; Biomarkers; Case-Control Studies; Cells, Cultured; Coronary Artery Disease; Endothelial Cells; Enzyme Inhibitors; Humans; Isomerism; Kidney Failure, Chronic; Kidney Function Tests; Middle Aged; Nitric Oxide; Nitric Oxide Synthase Type III; Risk Factors

Asymmetrical dimethylarginine (ADMA) is an inhibitor of nitric-oxide synthase. It has been linked to atherosclerotic risk in the general population as well as in end-stage renal disease patients (ESRD), whereas symmetrical dimethylarginine (SDMA) is thought to be biological inactive. Prospective data concerning the role of both dimethylarginines are rare in patients with chronic kidney disease.. 200 Patients with chronic kidney disease (mean age 57.6 +/- 13.0 years, 69 female, 131 male); 82 with chronic renal failure (CRF), 81 on maintenance haemodialysis (HD) and 37 renal transplant recipients (RTR) were prospectively followed for 24 months. ADMA and SDMA were measured by HPLC. The relation of plasma levels of ADMA and SDMA together with conventional risk factors for the cardiovascular and renal outcome was investigated with Cox proportional hazards model.. Mean serum levels of SDMA were significantly increased in all groups compared to the control group (P

Topics: Adult; Aged; Arginine; Atherosclerosis; Female; Follow-Up Studies; Humans; Kidney Failure, Chronic; Kidney Transplantation; Male; Middle Aged; Proportional Hazards Models; Risk Factors

To determine the association between asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase, with atherosclerosis in patients with chronic kidney disease (CKD).. One hundred thirty-eight CKD patients were enrolled in this study. Serum levels of L-arginine, ADMA, and SDMA were measured by high-performance liquid chromatography (HPLC). Common carotid arteries intimae-medial thickness (CCA-IMT), cross-sectional calculated intimae-medial thickness (cIM area) and atherosclerotic plaque were detected by noninvasive high-resolution B-mode ultrasonography.. Serum levels of ADMA and SDMA were significantly increased in CKD patients (n=138) compared with age matched healthy subjects (n=42, P<0.01). ADMA and SDMA levels increased with the progression of renal dysfunction and were negatively related to creatinine clearance (Ccr) in pre-dialysis patients (r=-0.315, P<0.05; r=-0.426, P<0.01). Serum levels of ADMA and SDMA in dialysis patients (n=74) were significantly higher than those in pre-dialysis patients (P<0.05). Patients with carotid artery plaques showed significantly higher levels of ADMA compared with those without plaques. Serum levels of ADMA closely correlated with the mean IMT (r=0.471, P<0.01) and cIM area value (r=0.430, P<0.01). These correlations remained significant even after adjusting GFR, age, gender ,and other risk factors for atherosclerosis in the multiple regression analysis.. Serum levels of ADMA increased with the progression of CKD and may play a role in the pathogenesis of accelerated atherosclerosis in CKD patients.

Topics: Adult; Arginine; Carotid Artery Diseases; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Nitric Oxide Synthase; Renal Dialysis

We examined whether endothelial function of the renal microcirculation was impaired in a model of chronic renal failure (CRF), and further assessed the role of asymmetrical dimethylarginine (ADMA) and its degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH), in mediating the deranged nitric oxide (NO) synthesis in CRF. CRF was established in male mongrel dogs by subtotal nephrectomy, and the animals were used in experiments after a period of 4 weeks. The endothelial function of the renal afferent and efferent arterioles was evaluated according to the response to acetylcholine, using an intravital needle-lens charge-coupled device camera. Intrarenal arterial infusion of acetylcholine (0.01 microg/kg/min) elicited 22+/-2% and 20+/-2% dilation of the afferent and efferent arterioles in normal dogs. In dogs with CRF, this vasodilation was attenuated (afferent, 12+/-2%; efferent, 11+/-1%), and the attenuation paralleled the diminished increments in urinary nitrite+nitrate excretion. In the animals with CRF, plasma concentrations of homocysteine (12.2+/-0.7 vs. 6.8+/-0.4 micromol/l) and ADMA were elevated (2.60+/-0.13 vs. 1.50+/-0.08 micromol/l). The inhibition of S-adenosylmethionine-dependent protein arginine N-methyltransferase by adenosine dialdehyde decreased plasma ADMA levels, and improved the acetylcholine-induced changes in urinary nitrite+nitrate excretion and arteriolar vasodilation. Acute methionine loading impaired the acetylcholine-induced renal arteriolar vasodilation in CRF, but not normal dogs, and the impairment in CRF dogs coincided with the changes in plasma ADMA levels. Real-time polymerase chain reaction revealed downregulation of the mRNA expression of DDAH-II in the dogs with CRF. Collectively, these results provide direct in vivo evidence of endothelial dysfunction in canine CRF kidneys. The endothelial dysfunction was attributed to the inhibition of the NO production by elevated ADMA, which involved the downregulation of DDAH-II. The deranged NO metabolic pathway including ADMA and DDAH is a novel mechanism for the aggravation of renal function.

Topics: Acetylcholine; Amidohydrolases; Animals; Arginine; Dogs; Down-Regulation; Endothelium, Vascular; Hypertension; Kidney Failure, Chronic; Male; Nitric Oxide; Polymerase Chain Reaction

Chronic kidney disease (CKD) is associated with increased cardiovascular events. The relationships between the markers of inflammation and endothelial dysfunction were investigated both before and after living donor kidney transplantation.. Twenty-seven renal transplant patients were studied. Eleven patients (six male, five female) were on cyclosporine A, whereas 16 patients (nine male, seven female) were treated with tacrolimus based regimes. Twenty-seven subjects (12 males, 15 females) were studied as controls. Plasma adiponectin, high sensitive C reactive protein (hsCRP), Asymetric dimethyl arginine (ADMA) levels were studied before transplantation and on days 1, 3, 7, 14, and 28. The brachial artery flow mediated dilatation (FMD) was studied before transplantation and on the 28th day.. Serum hsCRP and ADMA levels decreased significantly from the first posttransplantation day on each measurement (P<0.001 for all) while the decrement of plasma adiponectin started in the third day (P<0.001 for all). The FMD was lower in the patients than the control group (P<0.001) and improved significantly in the 28th day of transplantation (P<0.001).. The results indicate that ADMA is associated with FMD in CKD both before and after kidney transplantation. Endothelial functions improve at the very beginning of the posttransplantation period with accompanying reduction in ADMA and hsCRP levels.

Topics: Adult; Arginine; Biomarkers; Blood Glucose; Blood Pressure; C-Reactive Protein; Cohort Studies; Cyclosporine; Female; Humans; Immunosuppressive Agents; Kidney Failure, Chronic; Kidney Transplantation; Lipids; Living Donors; Male; Prospective Studies; Tacrolimus; Treatment Outcome

Increased blood levels of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) predict cardiovascular mortality in patients with end-stage renal disease. Despite its low molecular weight, available information on the impact of hemodialysis (HD) on ADMA plasma levels is controversial.. We assessed plasma concentrations, dialyzer clearance and total amount of ADMA removed in 30 patients with end-stage renal disease during regular HD. In addition, plasma ADMA levels were assessed in 10 patients with acute renal failure treated with extended HD.. Regular HD decreased plasma creatinine (from 774 +/- 42 to 312 +/- 17 micromol/l) and urea (from 24.5 +/- 1.5 to 8.4 +/- 0.5 mmol/l) concentrations significantly (both p < 0.001), whereas plasma ADMA remained unchanged (4.35 +/- 0.19 vs. 4.76 +/- 0.24 micromol/l). ADMA clearance was 92 +/- 6 ml/min, and the total amount removed in the spent dialysate was 37 +/- 4 micromol. The clearances of creatinine (161 +/- 3 ml/min) and of urea (173 +/- 3 ml/min) were significantly higher. Furthermore, even during extended HD, plasma ADMA concentrations did not decrease significantly (1.73 +/- 0.22 vs. 1.63 +/- 0.18 micromol/l).. In conclusion, dialysance of ADMA is markedly lower than expected from its molecular weight because of significant protein binding of the substance. Since markedly increased ADMA blood concentrations have been linked to cardiovascular complications due to atherosclerosis in patients with ESRD, new strategies should be evaluated to remove this putative uremic toxin.

Topics: Arginine; Cardiovascular Diseases; Creatine; Female; Humans; In Vitro Techniques; Kidney Failure, Chronic; Male; Middle Aged; Protein Binding; Renal Dialysis; Urea