3-nitrotyrosine and Kidney-Failure--Chronic

Increased myeloperoxidase (MPO) levels and activity are associated with increased cardiovascular risk among individuals with chronic kidney disease (CKD). However, a lack of good animal models for examining the presence and catalytic activity of MPO in vascular lesions has impeded mechanistic studies into CKD-associated cardiovascular diseases. Here, we show for the first time that exaggerated atherosclerosis in a pathophysiologically relevant CKD mouse model is associated with increased macrophage-derived MPO activity. Male 7-week-old LDL receptor-deficient mice underwent sham (control mice) or 5/6 nephrectomy and were fed either a low-fat or high-fat, high-cholesterol diet for 24 weeks, and the extents of atherosclerosis and vascular reactivity were assessed. MPO expression and oxidation products-protein-bound oxidized tyrosine moieties 3-chlorotyrosine, 3-nitrotyrosine, and

Topics: Animals; Aorta; Atherosclerosis; Blood Urea Nitrogen; Creatinine; Diet, Fat-Restricted; Diet, High-Fat; Dietary Fats; Disease Models, Animal; Disease Progression; Kidney Failure, Chronic; Kidney Function Tests; Lipids; Lipoproteins; Macrophages; Male; Mice; Mice, Knockout; Muscle Proteins; Nephrectomy; Oxidants; Oxidative Stress; Parathyroid Hormone; Peroxidase; Receptors, LDL; Tyrosine; Vasodilation

Endothelial dysfunction is a key vascular alteration in chronic kidney disease (CKD). Omega 3 (. 5/6 nephrectomized male Wistar rats (CKD;. Compared to SHAM, in CKD aortas EDD and eNOS expression were reduced (. Collectively, these findings indicate that

Topics: Animals; Aorta, Thoracic; Biomarkers; Endothelium, Vascular; Fatty Acids, Omega-3; Kidney Failure, Chronic; Male; NADPH Oxidase 4; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase Type III; Oxidative Stress; Rats; Rats, Wistar; Tyrosine

Atherosclerosis and vascular calcification are major contributors to cardiovascular morbidity and mortality among chronic kidney disease patients. The mevalonate pathway may play a role in this vascular pathology. Farnesyltransferase inhibitors such as R115777 block one branch of mevalonate pathway. We studied the effects of farnesyltransferase inhibitor R115777 on vascular disease in apolipoprotein E deficient mice with chronic renal failure and on mineral deposition in vitro.. Female uremic and non-uremic apolipoprotein E deficient mice were randomly assigned to four groups and treated with either farnesyltransferase inhibitor R115777 or vehicle. Farnesyltransferase inhibitor R115777 inhibited protein prenylation in mice with chronic renal failure. It decreased aortic atheromatous lesion area and calcification in these animals, and reduced vascular nitrotyrosine expression and total collagen as well as collagen type I content. Proteomic analysis revealed that farnesyltransferase inhibitor corrected the chronic renal failure-associated increase in serum apolipoprotein IV and α globin, and the chronic renal failure-associated decrease in serum fetuin A. Farnesyltransferase inhibitor further inhibited type I collagen synthesis and reduced mineral deposition in vascular smooth muscle cells in vitro, probably involving Ras-Raf pathway.. We show for the first time that farnesyltransferase inhibition slows vascular disease progression in chronic renal failure by both indirect systemic and direct local actions. This beneficial effect was mediated via a reduction in oxidative stress and favorable changes in vasoprotective peptides.

Topics: Animals; Aorta; Apolipoproteins E; Apoptosis; Atherosclerosis; Blood Proteins; Body Weight; Collagen Type I; Enzyme Inhibitors; Farnesyltranstransferase; Female; Kidney Failure, Chronic; Liver; Macrophages; Mevalonic Acid; Mice; Mice, Knockout; Muscle, Smooth, Vascular; Prenylation; Quinolones; Random Allocation; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tyrosine; Uremia; Vascular Calcification

Cardiovascular disease in chronic kidney disease (CKD) has peculiar characteristics. The aim of this study was to analyze atherosclerosis, vascular calcification and nitration in arteries from CKD patients.. External iliac and renal artery segments from 27 stage 5 CKD patients and 25 donor controls, respectively, were collected during the transplantation procedure.. CKD patients presented a significantly higher degree of lesion. In a large proportion (72%) of CKD patients, we observed vascular calcifications. Immunohistochemistry for nitrotyrosine revealed a significant increase in nitrotyrosine production in arteries from CKD patients compared with control donors. In addition, within CKD patients, nitrotyrosine staining was significantly stronger in arteries with media calcification when compared with arteries without media calcification.. The arteriopathy in the CKD patients appears in an early age and seems to be distinct from the arteriopathy of the general population, especially due to intense calcification and vascular oxidative stress.

Topics: Adult; Atherosclerosis; Case-Control Studies; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Proteins; Renal Artery; Risk Factors; Tyrosine; Vascular Calcification

Oxidative/nitrosative stress has long been demonstrated in hemodialysis patients. It is associated with numerous complications such as atherosclerosis and related cardiovascular disturbances. However, the factors influencing oxidative/nitrosative status have not been characterized extensively in these patients. Therefore, the present study was designed to investigate the alteration of oxidative/nitrosative stress parameters and total antioxidant status.. Forty-one hemodialysis patients and 41 healthy subjects were enrolled in the present study. Serum myeloperoxidase, nitrotyrosine and total antioxidant capacity were determined.. Serum myeloperoxidase and nitrotyrosine were significantly higher in the haemodialysis patients compared to the healthy subjects (P<0.05) while total antioxidant capacity was lower (P<0.01).. According to the results of this study, oxidative and nitrosative stress is increased in haemodialysis patients, therefore these alterations should be considered in the treatment of these patients.

Topics: Antioxidants; Biomarkers; Body Mass Index; Case-Control Studies; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Oxidation-Reduction; Oxidative Stress; Peroxidase; Renal Dialysis; Tyrosine

The CD40-CD40L system has been implicated in the pathogenesis of atherothrombotic complications in cardiovascular disease. The aim of this study was to determine the relationship between plasma soluble CD40 ligand (sCD40L) and symptomatic coronary heart disease (CHD) in end-stage renal disease (ESRD) patients on maintenance haemodialysis (HD).. This cross-sectional study included 57 HD patients, 31 of whom had symptomatic CHD. Lipid profile, markers of endothelial activation such as sCD40L, and both inflammatory and oxidative stress markers were measured and analyzed.. The sCD40L concentration was significantly higher in HD patients than in controls (1.34 +/- 0.53 vs 0.86 +/- 0.12 ng/mL, P < 0.01). Plasma concentration of sCD40L (P < 0.01), soluble vascular adhesion molecule-1 (sVCAM-1; P < 0.01) and high-sensitivity CRP (hsCRP; P < 0.01) were higher in HD patients with symptomatic CHD than in those without CHD. In addition, we also found that oxidative stress biomarkers such as nitrotyrosine (NT), malonaldehyde (MDA) and protein carbonyl (PC) were significantly elevated in patients with symptomatic CHD compared to those without. There was a strong overall positive relationship between sCD40L concentration and sVCAM-1 (r = 0.54, P < 0.001), MDA (r = 0.365, P < 0.01), NT (r = 0.293, r < 0.05) and log-transformed triglycerides (r = 0.275, P < 0.05).. Circulating concentrations of sCD40L were elevated in HD patients with symptomatic CHD. This study suggests that CD40-CD40L may play a potentially important role in the atherosclerotic complications of HD patients.

Topics: Adult; Aged; Aged, 80 and over; Biomarkers; C-Reactive Protein; Case-Control Studies; CD40 Ligand; Coronary Disease; Cross-Sectional Studies; Female; Humans; Inflammation Mediators; Kidney Failure, Chronic; Lipids; Male; Malondialdehyde; Middle Aged; Oxidative Stress; Pilot Projects; Protein Carbonylation; Renal Dialysis; Tyrosine; Up-Regulation; Vascular Cell Adhesion Molecule-1

The progressive deterioration of renal function and structure resulting from renal mass reduction are mediated by a variety of mechanisms, including oxidative stress and inflammation. Melatonin, the major product of the pineal gland, has potent_antioxidant and anti-inflammatory properties, and its production is impaired in chronic renal failure. We therefore investigated if melatonin treatment would modify the course of chronic renal failure in the remnant kidney model. We studied rats followed 12 wk after renal ablation untreated (Nx group, n = 7) and treated with melatonin administered in the drinking water (10 mg/100 ml) (Nx + MEL group, n = 8). Sham-operated rats (n = 10) were used as controls. Melatonin administration increased 13-15 times the endogenous hormone levels. Rats in the Nx + MEL group had reduced oxidative stress (malondialdehyde levels in plasma and in the remnant kidney as well as nitrotyrosine renal abundance) and renal inflammation (p65 nuclear factor-kappaB-positive renal interstitial cells and infiltration of lymphocytes and macrophages). Collagen, alpha-smooth muscle actin, and transforming growth factor-beta renal abundance were all increased in the remnant kidney of the untreated rats and were reduced significantly by melatonin treatment. Deterioration of renal function (plasma creatinine and proteinuria) and structure (glomerulosclerosis and tubulointerstitial damage) resulting from renal ablation were ameliorated significantly with melatonin treatment. In conclusion, melatonin administration improves the course of chronic renal failure in rats with renal mass reduction. Further studies are necessary to define the potential usefulness of this treatment in other animal models and in patients with chronic renal disease.

Topics: Actins; Animals; Blood Pressure; Cell Movement; Collagen Type IV; Creatinine; Disease Models, Animal; Hypertension; Hypertrophy; Inflammation; Kidney; Kidney Failure, Chronic; Leukocytes; Male; Malondialdehyde; Melatonin; Nephrectomy; Oxidative Stress; Proteinuria; Rats; Rats, Sprague-Dawley; Transcription Factor RelA; Transforming Growth Factor beta; Tyrosine

Reduction in nitric oxide (NO) levels during kidney failure has been related to the reaction of NO with superoxide anions to yield peroxynitrite which possesses the biological activity responsible for renal damage. However, stimulation of the NO pathway ameliorates the progression of kidney failure. Thus, it is unclear whether NO prevents or acts as the compound responsible for the cytotoxicity observed during kidney failure.. We evaluated the development of kidney failure in animals that were wild type and deficient in endothelial NO synthase (eNOS -/-) and tested the effects of an antioxidant treatment and NO precursors on the generation of superoxide anion and kidney failure parameters.. In wild-type mice, five-sixths nephrectomy increased proteinuria from 3.0 +/- 0.35 to 14.5 +/- 0.76 mg protein/24 h (P < 0.05), blood pressure from 83.1 +/- 1.8 to 126.6 +/- 1.7 mmHg (P < 0.05), and superoxide production from 1.4 +/- 0.6% to 74.3 +/- 0.8% (P < 0.05). The effects of five-sixths nephrectomy on the eNOS -/- mice were greater compared with wild-type mice. Proteinuria increased from 6.7 +/- 0.5 to 22.7 +/- 2.0 mg protein/24 h (P < 0.05), blood pressure increased from 93.3 +/- 0.9 to 151.2 +/- 3.4 mmHg (P < 0.05), and superoxide production increased from 12.9 +/- 0.5% to 99.8 +/- 1.3% (P < 0.05). The nitrotyrosine levels were lower in eNOS -/- mice as compared to wild-type mice. A combination of L-arginine and antioxidant treatment ameliorated renal damage. The effect was improved in wild-type animals.. Our data support the relevance of NO as an antagonist to superoxide in renal tissues and suggest that the loss of this mechanism promotes the progression of kidney failure.

Topics: Animals; Antioxidants; Arginine; Blood Pressure; Disease Models, Animal; Drug Combinations; Kidney; Kidney Failure, Chronic; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nephrectomy; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Proteinuria; Superoxides; Time Factors; Tyrosine

Glycation, oxidation, and nitration of endogenous proteins occur spontaneously and these modifications are also present in foods. Increased levels of these chemical changes are associated with chronic renal failure; however, little is known about acute kidney failure. We measured these modifications of plasma protein and related free adducts in plasma following bilateral nephrectomy and bilateral ureteral obstruction. Advanced glycation end-product (AGE) residues of plasma protein were increased 3 h post-surgery, and thereafter slowly decreased in all groups, reflecting changes in plasma protein synthesis and transcapillary flow post-surgery. Ureteral ligation increased oxidation and nitration adduct residues. There were, however, marked increases in AGE, dityrosine, or 3-nitrotyrosine free adducts in both nephrectomized and ureter-ligated rats compared to rats that had undergone sham operations. There were lower modified adduct concentrations in the ureter-ligated compared to the nephrectomized rats, reflecting residual glomerular filtration and tubular removal. There was no increase in glycated, oxidized, and nitrated proteins. Glyoxal and methylglyoxal were also increased in both renal failure models. Our study shows that the acute loss of renal function and urinary excretion leads to the accumulation of AGE, oxidation, and nitration free adducts in the plasma.

Topics: Animals; Body Weight; Disease Models, Animal; Glycation End Products, Advanced; Glyoxal; Kidney Failure, Chronic; Ligation; Male; Nephrectomy; Oxidative Stress; Pyruvaldehyde; Rats; Rats, Wistar; Tyrosine

Patients with chronic renal failure (CRF) are at a greatly increased risk of cardiovascular mortality. This fact could be due to the presence of conventional risk factor and specific uremic as increase of oxidative stress, hyperhomocystaenemia, deranged calcium-phosphate metabolism and chronic inflammatory state. In order to analyze the vascular effects of CRF, we studied the histomorphometric characteristics (intima-media thickness and monocyte chemoattractant protein (MCP-1) accumulation (inmunohistochemical) on radial artery from 13 patients with CRF. We determined by Western blot analysis, the vascular nitrotyrosin abundance (footprint of nitric oxide (NO) inactivation by reactive oxygen species (ROS), and the endothelial nitric oxide synthase (eNOS) expression. The NOS activity was, also, determined. The results were compared with those obtained in pudenda artery from a healthy control group (n: 16). The CRF group showed a significant increase in intima and media thickness 108 +/- 16 vs 14 +/- 2.5 microm, p < 0.001 and 291 +/- 19 vs 153 +/- 15 microm, p < 0.001, respectively). The CRF group exhibited a marked elevation of MCP-1 vascular expression (2 +/- 0.15 vs 0.6 +/- 0.12 u, p < 0.001). A significant positive correlation was found between MCP-1 vascular expression and its inmunohistochemical deposits (r: 0.98, p < 0.0001). Nitrotyrosin abundance (western blot) was significantly increased in artery of CRF patients (2.1 +/- 0.1 vs 0.42 +/- 0.1 u, p < 0.0001). No significant differences was found in NOS activity between CRF and control groups. However, eNOS expression was greatly increased in the CRF patients (1.73 +/- 0.1 vs 0.67 +/- 0.1 u, p < 0.001). A significant positive correlation was found between nitrotyrosin and eNOS expression and systolic arterial pressure. However, the differences between CRF and control groups persisted after statistically fitting to arterial pressure. The present study demonstrate that in CRF there are arterial preatherosclerotic changes and an increase of vascular nitrotyrosin accumulation, which is the footprint of NO inactivation by ROS. The secondary NO inactivation can, in turn, contribute to eNOS vascular upregulation.

Topics: Blood Vessels; Cytokines; Endothelium; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Nitric Oxide Synthase; Tyrosine; Vascular Diseases

It has been shown that reactive oxygen species are involved in chronic puromycin aminonucleoside (PAN) induced nephrotic syndrome (NS) and that a 20% soy protein diet reduces renal damage in this experimental model. The purpose of the present work was to investigate if a 20% soy protein diet is able to modulate kidney nitrotyrosine formation and the activity of renal antioxidant enzymes (catalase, glutathione peroxidase, Cu,Zn- or Mn-superoxide dismutase) which could explain, at least in part, the protective effect of the soy protein diet in rats with chronic NS induced by PAN. Four groups of rats were studied: (1) Control rats fed 20% casein diet, (2) Nephrotic rats fed 20% casein diet, (3) Control rats fed 20% soy protein diet, and (4) Nephrotic rats fed 20% soy protein diet. Chronic NS was induced by repeated injections of PAN and rats were sacrificed at week nine. The soy protein diet ameliorated proteinuria, hypercholesterolemia, and the increase in serum creatinine and blood urea nitrogen observed in nephrotic rats fed 20% casein diet. Kidney nitrotyrosine formation increased in nephrotic rats fed 20% casein diet and this increase was ameliorated in nephrotic rats fed 20% soy protein diet. However, the soy protein diet was unable to modulate the antioxidant enzymes activities in control and nephrotic rats fed 20% soy protein diet. Food intake was similar in the two diet groups. The protective effect of a 20% soy protein diet on renal damage in chronic nephropathy induced by PAN was associated with the amelioration in the renal nitrotyrosine formation but not with the modulation of antioxidant enzymes.

Topics: Animals; Antimetabolites; Antioxidants; Blood Urea Nitrogen; Body Weight; Catalase; Cholesterol; Creatinine; Diet; Eating; Glutathione Peroxidase; Glycine max; Immunohistochemistry; Kidney; Kidney Failure, Chronic; Kidney Function Tests; Lipids; Male; Proteinuria; Puromycin Aminonucleoside; Rats; Rats, Wistar; Soybean Proteins; Superoxide Dismutase; Tyrosine

A growing body of evidence suggesting that oxidative stress might be one of the most important complications occurring during hemodialysis (HD) has accumulated. However, although the role of reactive oxygen species has been investigated extensively, little is known about the involvement of reactive nitrogen species. In the present investigation, levels of protein modifications in the form of tyrosine nitration in patients undergoing long-term HD therapy were evaluated.. Tyrosine nitration of plasma proteins was detected by means of Western blotting using a specific nitrotyrosine-recognizing monoclonal antibody, and band intensity was evaluated by using image analysis software. Immunoprecipitation of plasma proteins by antinitrotyrosine-agarose--conjugated antibodies, followed by Western blotting, was used in an attempt to identify the nitrated proteins.. Although several proteins with nitrated tyrosine residues were observed in plasma of healthy individuals, increased nitration levels were observed in some specific proteins in all patients tested (n = 25) compared with controls (n = 6). At least 6 apparent bands appeared to be more nitrated than their counterparts in plasma from controls. Ceruloplasmin was identified as 1 of the proteins with significantly increased nitration in patients.. Results of the present investigation show that specific plasma proteins of HD patients are post-translationally modified by nitration of their tyrosine residues. The nature of these proteins, as well as the exact molecular mechanisms and consequences of these modifications, warrant additional investigation.

Topics: Adult; Aged; Aged, 80 and over; Blood Proteins; Blotting, Western; Female; Humans; Image Processing, Computer-Assisted; Kidney Failure, Chronic; Male; Middle Aged; Nitric Oxide; Oxidative Stress; Renal Dialysis; Tyrosine

An impairment of nitric oxide (NO) bioavailability and/or metabolism may contribute to the excessive incidence of atherosclerotic complications observed in haemodialysis (HD) patients. Recent evidence indicates that NO metabolism involves a family of NO-related molecules that have not yet been explored in such patients. The aim of our study was to determine the plasma levels of S-nitrosothiol and nitrotyrosine in chronic HD patients, and to evaluate potential factors influencing their levels.. Plasma levels of S-nitrosothiols and nitrotyrosine were determined in 22 non-smoking HD patients and 12 healthy control subjects, together with albumin, homocysteine, haemoglobin, highly sensitive C-reactive protein (hsCRP) and various components of the oxidant-antioxidant system at the plasma and erythrocyte levels.. While plasma nitrosothiol levels were significantly higher in HD patients than in controls (2.25 +/- 1.17 vs 0.45 +/- 0.45 micromol/l, respectively, P < 0.0001), nitrotyrosine levels were not different. HD patients also exhibited a marked deficit of ascorbate and low plasma glutathione peroxidase activity. An inverse relationship was found between plasma S-nitrosothiol and blood haemoglobin in HD patients (P < 0.005). No direct relationship was observed between plasma S-nitrosothiol levels and any of the oxidative stress markers, or hsCRP levels.. This study demonstrates high plasma S-nitrosothiol levels in HD patients, which are partially related to low blood haemoglobin concentrations. The pathophysiological significance of this elevation remains to be elucidated. A possible protective role against nitrosative stress is suggested in presence of normal plasma nitrotyrosine levels in such patients.

Topics: Biomarkers; C-Reactive Protein; Erythrocytes; Female; Glutathione; Glutathione Peroxidase; Humans; Iron; Kidney Diseases; Kidney Failure, Chronic; Male; Middle Aged; Nitric Oxide; Reference Values; Renal Dialysis; S-Nitrosothiols; Transferrin; Tyrosine

Nitric oxide (NO.) is produced by NO synthases (NOS) and can interact with reactive oxygen species (ROS) to form peroxynitrite, which induces protein damage by formation of nitrotyrosine. NO. has a promotional effect on acute rejection. To investigate the role of NO. during chronic renal transplant failure (CRTF), we studied the expression of eNOS and iNOS in conjunction with H2O2 production and the formation of nitrotyrosines. Nephrectomy material from 10 patients and 10 control kidneys was used in this study. Expression of iNOS, eNOS, nitrotyrosine and the presence of ROS-producing cells and macrophages were determined using immunohistochemistry. INOS expression in nonsclerosed glomeruli and interstitium was significantly increased in patients with CRTF (p < 0.05). Glomerular eNOS expression was decreased in patients with CRTF compared with glomeruli of control kidneys (p < 0.01). Nitrotyrosine and ROS positive cells were significantly increased in CRTF in the interstitium (p < 0.05), but not in glomeruli. In summary, we found a marked interstitial increase in iNOS protein expression together with a decrease in glomerular eNOS expression in CRTF patients, associated with a significant increment in ROS and nitrotyrosine-positive cells in the interstitium. Our results suggest that loss of NO. production by glomerular eNOS in conjunction with an increased NO. production by interstitial iNOS, together with the formation of ROS and nitrotyrosine, is involved in the pathogenesis of CRTF.

Topics: Adult; Female; Graft Rejection; Humans; Immunohistochemistry; Kidney Failure, Chronic; Kidney Transplantation; Male; Middle Aged; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Peroxynitrous Acid; Reactive Oxygen Species; Transplantation, Homologous; Tyrosine

Aged spontaneously hypertensive rats (SHR) develop end-stage renal disease resembling that of uncontrolled essential hypertension in humans. Nitric oxide (NO) and angiotensin II (Ang II) play an important role in the regulation of blood pressure and the growth of vascular smooth muscle and renal mesangial cells. The relationship between renal NO system, Ang II activity and renal injury in aged SHR is not fully understood.. The 8-week-old SHR were randomized into losartan-treated (30 mg/kg/day for 55 weeks) and vehicle treated groups. The age-matched Wistar-Kyoto rats (WKY) served as controls. Renal histology and tissue expressions of endothelial and inducible NO synthases (eNOS and iNOS) and nitrotyrosine were examined at 63-weeks of age.. Compared to the WKY group, untreated SHR showed severe hypertension, proteinuria, renal insufficiency, a twofold decrease in renal tissue eNOS and iNOS expressions and massive nitrotyrosine accumulation. This was associated with severe glomerulosclerosis, tubular atrophy and interstitial fibrosis. Losartan therapy normalized blood pressure, prevented proteinuria and renal insufficiency, abrogated the fall in renal eNOS and iNOS protein contents, mitigated renal nitrotyrosine accumulation, and prevented the histological abnormalities found in the untreated SHR.. Aged SHR exhibit severe renal lesions with acquired NO deficiency that are prevented by hypertension control with AT1 blockade. These findings point to the possible role of NO deficiency in the pathogenesis of renal lesions in aged SHR.

Topics: Aging; Angiotensin Receptor Antagonists; Animals; Antihypertensive Agents; Arterioles; Hypertension, Renal; Immunoenzyme Techniques; Kidney Failure, Chronic; Kidney Glomerulus; Losartan; Male; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Angiotensin, Type 1; Tyrosine

Chronic renal failure (CRF) is associated with oxidative stress which promotes production of reactive carbonyl compounds and lipoperoxides leading to the accumulation of advanced glycation and lipoxidation end products. Reactive oxygen species (ROS) avidly reacts with nitric oxide (NO) producing cytotoxic reactive nitrogen species capable of nitrating proteins and damaging other molecules. This study tested the hypothesis that CRF results in enhanced ROS-mediated NO inactivation and protein nitration which can be ameliorated with antioxidant therapy. Male Sprague Dawley rats were randomized to CRF (5/6 nephrectomy) and sham-operated controls and fed either a regular diet (vitamin E, 40 U/Kg food) or an antioxidant-fortified diet (vitamin E, 5000 U/Kg food) for 6 weeks. Blood pressure, plasma malondialdehyde (MDA), tissue NO synthase (NOS) isoforms, tissue nitrotyrosine (the footprint of NO interaction with ROS), and vascular tissue NO production were determined. CRF resulted in marked elevations of blood pressure, plasma MDA, and tissue nitrotyrosine abundance, but did not change plasma L-arginine level. This was coupled with depressed vascular tissue NO production and reduced immunodetectable NOS proteins in the vascular, renal, and cardiac tissues. Antioxidant therapy ameliorated the CRF-induced hypertension, improved vascular tissue NO production, lowered tissue nitrotyrosine burden, and reversed downregulations of NOS isoforms. In contrast, antioxidant therapy had no effects in the controls. CRF is associated with oxidative stress which promotes NO inactivation by ROS leading to functional NO deficiency, hypertension, and widespread accumulation of protein nitration products. Amelioration of oxidative stress by high-dose vitamin E enhances NO availability, improves hypertension, lowers protein nitration products, and increases NOS expression and vascular NO production in CRF animals.

Topics: alpha-Tocopherol; Animals; Antioxidants; Arginine; Creatinine; Endothelium, Vascular; Kidney Failure, Chronic; Male; Muscle, Smooth, Vascular; Nitrates; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Proteins; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Tyrosine

Interaction of reactive oxygen species with nitric oxide promotes nitric oxide inactivation and generation of cytotoxic reactive nitrogen species that attack DNA, lipids, and proteins. Nitration of free tyrosine and tyrosine residues of proteins results in production of nitrotyrosine, which can lead to excitotoxicity and frequently is found in the brain of patients and animals with various degenerative, ischemic, toxic, and other neurologic disorders. According to earlier studies, reactive oxygen species activity is increased and neuronal NO synthase expression in the brain is elevated in animals with chronic renal failure (CRF). It was hypothesized, therefore, that tyrosine nitration must be increased in the uremic brain. This hypothesis was tested, through determination of nitrotyrosine abundance (by Western blot analysis), as well as distribution (by immunohistology), in the cerebrum of rats with CRF 6 wk after 5/6 nephrectomy. The results were compared with those of sham-operated controls and antioxidant (lazaroid)-treated and captopril-treated rats with CRF. Western blot analysis revealed a significant increase in nitrotyrosine abundance in the cerebral cortex of rats with CRF. This was accompanied by an intense nitrotyrosine staining of the neuronal processes, including proximal segments of dendrites, axons, and axon terminals of the cortical neurons. Both antioxidant therapy and captopril administration alleviated oxidative stress (as evidenced by normalization of plasma lipid peroxidation product malondialdehyde) and significantly reduced nitrotyrosine abundance in the cerebral cortex of the treated CRF group. In conclusion, CRF resulted in oxidative stress and increased tyrosine nitration in the cerebral cortex. Antioxidant therapy and angiotensin-converting enzyme inhibition alleviated the CRF-induced oxidative stress and mitigated tyrosine nitration in the rats with CRF.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antioxidants; Blotting, Western; Brain; Captopril; Kidney Failure, Chronic; Male; Pregnatrienes; Rats; Rats, Sprague-Dawley; Tissue Distribution; Tyrosine

Topics: Animals; Antioxidants; Brain Diseases; Humans; Kidney Failure, Chronic; Oxidative Stress; Rats; Tyrosine

The production of both nitric oxide (NO) and superoxide increases in septic shock. The cogeneration of these molecules is known to yield peroxynitrite, which preferentially nitrates tyrosine residues of protein and non-protein origins. We present evidence of peroxynitrite production in septic shock by measuring plasma nitrotyrosine. The nitrotyrosine was measured by an HPLC C-18 reverse-phase column and ultraviolet detector in chronic renal failure patients with or without septic shock, and in healthy volunteers. Plasma nitrite + nitrate (NOx) was also measured to evaluate NO production. Nitrotyrosine was selected as an index for production of peroxynitrite because the direct measurement of peroxynitrite in vivo is difficult. Patients with renal failure were selected in order to minimize nitrotyrosine excretion through the kidney. Plasma nitrotyrosine levels were not detectable in volunteers, 28.0 +/- 12.3 microM (1.6 +/- 1.1% of total tyrosine) in renal failure patients without septic shock, and 118.2 +/- 22.0 microM (5.5 +/- 1.2% of total tyrosine) in patients with septic shock. NOx levels were also higher in patients with septic shock than in patients without septic shock (173.9 +/- 104.7 vs. 75.6 +/- 19.1 microM). Although renal failure itself increases plasma concentrations of both molecules, the higher levels in patients with septic shock suggest that peroxynitrite is generated and the nitration of tyrosine residues is increased in this disease.

Topics: Adult; Aged; Aged, 80 and over; Case-Control Studies; Female; Free Radicals; Humans; Kidney Failure, Chronic; Male; Middle Aged; Nitrates; Nitric Oxide; Shock, Septic; Superoxides; Tyrosine