Blood Nitric Oxide Metabolites Research Articles

ENDOTHELIAL DYSFUNCTION AND GASTROESOPHAGEAL REFLUX DISEASE: STUDY OF COMMON PATHOGENETIC MECHANISMS AND WAYS OF CORRECTION

The aim. To determine the role and place of endothelial dysfunction in the pathogenesis of comorbid gastroesophageal reflux disease (GERD) and obesity by studying the levels of nitric oxide (NO) metabolites in blood and urine. To evaluate the efficacy and benefits of the prescribed therapy, which included the additional inclusion of a peptide compound analogous to leu-enkephalin tyrosine-2-alanine-glycine-phenylalanine-leucyl-arginine diacetate (Dalargin).
 Materials and methods. Clinical manifestations were assessed using the GERD-HRQL questionnaire, levels of stable nitric oxide metabolites NO2 and total metabolites NO2 + NO3 were determined by spectrophotometric method, leptin levels were determined by enzyme-linked immunosorbent assay, pH-metry and motor function was studied by ultrasound. 130 patients were examined, including 70 patients with GERD with comorbid obesity of the first degree, 40 patients with GERD without concomitant pathology and 20 healthy individuals. The study was divided into 3 groups.
 Results. It was determined that the levels of stable metabolites NO2, NO2 + NO3 in blood and urine in the group of GERD with obesity are significantly lower than in the group of isolated GERD (p<0.001). A direct correlation between the level of nitric oxide metabolites in blood and urine and acidity in the stomach and oesophagus was established; an inverse relationship between NO metabolites and the degree of gastrointestinal motor and functional disorders, the severity of clinical manifestations, and the level of hormonal secretion by adipocytes. The supplemental inclusion of Dalargin improved the effectiveness and quality of pathogenetic therapy and achieved a more positive disease dynamics and is recommended for prescription in practice.
 Conclusions. Obesity is a predictor of a more severe course of GERD and more severe endothelial dysfunction. There is a correlation between the severity of endothelial dysfunction and the degree of functional, motor and secretory disorders of the stomach and oesophagus.

REACTIVE OXYGEN AND NITROGEN SPECIES ROLE IN EXPERIMENTAL PERIODONTITIS DEVELOPMENT

Introduction. Activation of lipid peroxidation is one of the trigger mechanisms of periodontium injury, which is primary caused by cellular damage. Reactive oxygen and nitrogen species (RONS) are able to cause damage to a cell as well as final products of lipid peroxidation, including unsaturated aldehydes and other metabolites. Objective. The aim of the research was to determine the role of RONS and accumulation of lipid peroxidation derivatives in initial development and formation of chronical inflammatory process in periodontium. Methods. Experimental periodontitis was modeled in animals by injection of complex mixtures of microorganisms diluted in egg protein into periodontal tissues. The results of biochemical studies of free radical processes activity in blood serum were evaluated by content of diene, triene conjugates, TBA-active products and total quantity of metabolites of nitric oxide (NO2–+NO3–), which were determined on the 7th, 14th and 30th days of the experiment. Results. Generation of active forms of oxygen is more influential, providing longevity of inflammatory process. This pays attention to typical dynamics of changes in active processes of lipid peroxidation in the development and course of experimental periodontitis. The study of inflammatory process with a bacterial-immune component in the rats’ periodontal complex proved accumulation of lipid peroxidation and nitric oxide metabolites in blood serum.Conclusions. The preservation of increased lipid peroxidation and nitric oxide metabolites in blood serum of the experimental animals with acute periodontitis conduce enhance of alteration and delayed healing that result in its sequel into chronical periodontitis.

Interaction of Pro- and Antioxidant Factors, Nitric Oxide Metabolites in Blood and Gingival Tissues during Experimental Chronic Gastritis and Duodenitis

The stable metabolites rate of nitric oxide is reduced three times compared with the rate in the group of control animals in homogenates of rats’ gingival tissue with gastritis and duodenitis. Increasing of the catalase rate with simultaneous increasing of lipids and proteins oxidation was accompanied by decreasing activity of superoxide dismutase. Decreasing of the malonic dialdehyde content and indices protein molecules fragmentation in the blood plasma with simultaneous increasing of catalase and nitric oxide metabolites levels indicates the leading role of nitric oxide in antioxidant protection of the organism in conditions of disease.

The ACE I/D polymorphism is associated with nitric oxide metabolite and blood pressure levels in healthy Mexican men.

The I/D insertion/deletion polymorphism of the angiotensin-converting enzyme has been related to hypertension. This polymorphism also seems to have gender related implications. Angiotensin II contributes to the production and release of oxygen reactive species that react with nitric oxide, inactivating its effects. To establish whether the ACE I/D polymorphism correlates with nitric oxide plasma metabolites in healthy men and women. Among 896 subjects between 18 and 30 years of age range, 138 fulfilled inclusion criteria. The polymorphism was identified by polymerase chain reaction, and blood nitric oxide metabolites were analyzed following the method described by Bryan. Both systolic and diastolic arterial pressures were higher in men than in women (107/67 vs. 101/65 mm Hg, p<0.001). In terms of the ACE gene, there were differences in the concentration of nitric oxide metabolites in men with the I/D and D/D genotypes when compared to carriers of the I/I genotype (33.55 and 29.23 vs. 53.74 pmol/ml; p=<0.05), while there were no significant differences in women when compared by genotype. Men with the D/D genotype had higher systolic blood pressure than I/D carriers (111 vs. 104 mm Hg, p<0.05). We observed no arterial blood pressure differences in women when grouped by ACE genotype. The ACE D/D genotype was associated with nitric oxide metabolite levels and systolic blood pressure in clinically healthy men while it had no effect in women.

Neuronal nitric oxide synthase (NOS1) and its adaptor, NOS1AP, as a genetic risk factors for psychiatric disorders.

Nitric oxide (NO) is a gaseous transmitter produced by nitric oxide synthases (NOSs). The neuronal isoform (NOS-I, encoded by NOS1) is the main source of NO in the central nervous system (CNS). Animal studies suggest that nitrinergic dysregulation may lead to behavioral abnormalities. Unfortunately, the large number of animal studies is not adequately reflected by publications concerning humans. These include post-mortem studies, determination of biomarkers, and genetic association studies. Here, we review the evidence for the role of NO in psychiatric disorders by focusing on the human NOS1 gene as well as biomarker studies. Owing to the complex regulation of NOS1 and the varying function of NOS-I in different brain regions, no simple, unidirectional association is expected. Rather, the 'where, when and how much' of NO formation is decisive. Present data, although still preliminary and partially conflicting, suggest that genetically driven reduced NO signaling in the prefrontal cortex is associated with schizophrenia and cognition. Both NOS1 and its interaction partner NOS1AP have a role therein. Also, reduced NOS1 expression in the striatum determined by a length polymorphism in a NOS1 promoter (NOS1 ex1f-VNTR) goes along with a variety of impulsive behaviors. An association of NOS1 with mood disorders, suggested by animal models, is less clear on the genetic level; however, NO metabolites in blood may serve as biomarkers for major depression and bipolar disorder. As the nitrinergic system comprises a relevant target for pharmacological interventions, further studies are warranted not only to elucidate the pathophysiology of mental disorders, but also to evaluate NO function as a biomarker.

L-Arginine supplementation improves exercise capacity after a heart transplant

Endothelial dysfunction is associated with the decreased exercise capacity observed in heart-transplant (HTx) recipients. L-arginine supplementation (LAS) stimulates the nitric oxide (NO) pathway and restores endothelial function. We compared exercise capacity in healthy subjects and HTx patients and investigated whether chronic LAS might improve exercise capacity and NO/endothelin balance after an HTx. Clinical, echocardiographic, and exercise characteristics were measured in 11 control subjects and 22 HTx recipients. In a prospective, double-blind study, the 22 HTx recipients performed a 6-min exercise [6-min-walk test (6MWT)] and a maximal bicycle exercise test before and after a 6-wk period of placebo intake or LAS. Endothelial function was measured by analyzing blood NO metabolites, endothelin, and the resulting NO/endothelin balance. Exercise capacity decreased after transplantation. Unlike with the placebo intake, 6 wk of LAS improved quality of life in HTx recipients (mean +/- SEM Minnesota Score: from 15.3 +/- 1.3 to 10.6 +/- 1.1; P < 0.001) and their submaximal exercise capacity. The distance walked during the 6MWT increased (from 525 +/- 20 to 580 +/- 20 m; P = 0.002), and the ventilatory threshold during the incremental test was delayed by 1.2 min (P = 0.01). Central factors such as resting stroke volume, systolic pulmonary arterial pressure, cardiac systolodiastolic functions, and heart-rate reserve were not modified, but LAS significantly increased the NO:endothelin ratio (from 2.49 +/- 0.38 to 3.31 +/- 0.39; P = 0.03). Oral LAS may be a useful adjuvant therapeutic to improve quality of life and exercise tolerance in HTx recipients.

Preservation of Endothelium Nitric Oxide Release by Pulsatile Flow Cardiopulmonary Bypass When Compared With Continuous Flow

The aim of this work is to analyze endothelium nitric oxide (NO) release in patients undergoing continuous or pulsatile flow cardiopulmonary bypass (CPB). Nine patients operated under continuous flow CPB, and nine patients on pulsatile flow CPB were enrolled. Plasma samples were withdrawn for the chemiluminescence detection of nitrite and nitrate. Moreover the cellular component was withdrawn for the detection of nitric oxide synthase (NOS) activity in the erythrocytes, and an estimation of systemic inflammatory response was carried out. Significant reduction in the intraoperative concentration with respect to the preoperative was observed only under continuous flow CPB for both nitrite and NO(x) (nitrite + nitrate) concentration (P = 0.010 and P = 0.016, respectively). Significant difference in intraoperative nitrite concentration was also observed between the groups (P = 0.012). Finally, erythrocytes showed a certain endothelial NOS activity, which did not differ between the groups, and no differences in the inflammatory response were pointed out. The significant reduction of NO(2)(-) concentration under continuous perfusion revealed the strong connection among perfusion modality, endothelial NO release, and plasmatic nitrite concentration. The similar erythrocyte eNOS activity between the groups revealed that the differences in blood NO metabolites are mainly ascribable to the endothelium release.

Brief Periods of Nitric Oxide Inhalation Protect against Myocardial Ischemia–Reperfusion Injury

Prolonged breathing of nitric oxide reduces myocardial ischemia-reperfusion injury, but the precise mechanisms responsible for the cardioprotective effects of inhaled nitric oxide are incompletely understood. The authors investigated the fate of inhaled nitric oxide (80 parts per million) in mice and quantified the formation of nitric oxide metabolites in blood and tissues. The authors tested whether the accumulation of nitric oxide metabolites correlated with the ability of inhaled nitric oxide to protect against cardiac ischemia-reperfusion injury. Mice absorbed nitric oxide in a nearly linear fashion (0.19 +/- 0.02 micromol/g x h). Breathing nitric oxide rapidly increased a broad spectrum of nitric oxide metabolites. Levels of erythrocytic S-nitrosothiols, N-nitrosamines, and nitrosyl-hemes increased dramatically within 30 s of commencing nitric oxide inhalation. Marked increases of lung S-nitrosothiol and liver N-nitrosamine levels were measured, as well as elevated cardiac and brain nitric oxide metabolite levels. Breathing low oxygen concentrations potentiated the ability of inhaled nitric oxide to increase cardiac nitric oxide metabolite levels. Concentrations of each nitric oxide metabolite, except nitrate, rapidly reached a plateau and were similar after 5 and 60 min. In a murine cardiac ischemia-reperfusion injury model, breathing nitric oxide for either 5 or 60 min before reperfusion decreased myocardial infarction size as a fraction of myocardial area at risk by 31% or 32%, respectively. Breathing nitric oxide leads to the rapid accumulation of a variety of nitric oxide metabolites in blood and tissues, contributing to the ability of brief periods of nitric oxide inhalation to provide cardioprotection against ischemia-reperfusion injury. The nitric oxide metabolite concentrations achieved in a target tissue may be more important than the absolute amounts of nitric oxide absorbed.

Extrapulmonary effects of nitric oxide inhalation therapy: time to consider new dosing regimes?

Studies with nitric oxide (NO) inhalation suggest transformation of NO in the lung into a more long-lived bioactive NO species that also has distal effects [1,2]. The exact nature of these species has not been pinpointed, but probable candidates include circulating nitrite anions and/or S-nitrosothiols [3]. When using inhaled NO therapeutically for pulmonary disorders, the dose is typically expressed as the concentration of NO without adjustments for body size. When inhaling 10 ppm NO, the concentration of NO that reaches the lungs with every breath is the same whether it in a mouse, a premature infant or an adult. The minute ventilation in relation to body weight, however, is about three to four times higher in a premature infant compared with an adult, so the resulting accumulation of bioactive NO metabolites in blood is much greater. This greater accumulation suggests that the dose of inhaled NO should be adjusted in relation to body weight, and also calls for some caution when extrapolating results from animal data to humans. A concentration of inhaled NO that is effective in a small animal may therefore not be sufficient in humans. Conversely, a concentration that is effective and safe in adults may cause unwanted toxic effects in premature infants. Several factors will affect the metabolism of inhaled NO into bioactive circulating NO species. The vast majority of inhaled NO eventually ends up as nitrate, which is considered biologically inert. In awake subjects, however, nitrate undergoes enterosalivary circulation and is reduced to nitrite in the oral cavity [4]. Swallowed nitrite then reenters the circulation, where it can be further reduced to bioactive NO [5]. In intubated sedated patients the enterosalivary nitrate/nitrite cycle is disrupted, and consequently less nitrite is generated. The levels of circulating NO species will also depend on NO oxidation in blood into nitrite, on renal excretion and on the activity of the reductive systems that ultimately catalyse NO formation from the circulating NO metabolites [3]. In summary, it is clear that inhaled NO has distal effects outside the lungs that may be harnessed therapeutically in the future; for example, in the prevention of ischemia-reperfusion injury. Although the precise nature of the NO metabolite(s) responsible for these effects remains to be pinpointed, there are indications that the nitrite anion plays an active role. In experimental settings and in future clinical trials we should consider adjusting the dose of inhaled NO in relation to body size and should consider other factors that may affect the transduction of NO bioactivity to the target organ. Finally, the possibility of delivering the active NO metabolites directly instead of via NO inhalation should also be considered.

Differential nitros(yl)ation of blood and tissue constituents during glyceryl trinitrate biotransformation in vivo

Nitric oxide (NO)-derived products may modify tissue constituents, forming S- and N-nitroso adducts and metal nitrosyls implicated in NO signaling. Nitrovasodilator drugs have been in widespread use for more than a century, yet their biotransformation pathways to NO and their effects as NO donors across tissues remain ill defined. By using a metabonomics approach (termed "NObonomics") for detailing the global NO-related metabolism of the cornerstone nitrovasodilator, glyceryl trinitrate (GTN; 0.1-100 mg/kg), in the rat in vivo, we find that GTN biotransformation elicits extensive tissue nitros(yl)ation throughout all major organ systems. The corresponding reaction products remained detectable hours after administration, and vascular tissue was not a major nitros(yl)ation site. Extensive heart and liver modifications involved both S- and N-nitrosation, and RBC S-nitrosothiol formation emerged as a sensitive indicator of organic nitrate metabolism. The dynamics of GTN-derived oxidative NO metabolites in blood did not reflect the nitros(yl)ation patterns in the circulation or in tissues, casting doubt on the usefulness of plasma nitrite/nitrate as an index of NO/NO-donor biodynamics. Target-tissue NO metabolites varied in amount and type with GTN dose, suggesting a dose-sensitive shift in the prevailing routes of GTN biotransformation ("metabolic shunting") from thiol nitrosation to heme nitrosylation. We further demonstrate that GTN-induced nitros(yl)ation is modulated by a complex, tissue-selective interplay of enzyme-catalyzed pathways. These findings provide insight into the global in vivo metabolism of GTN at pharmacologically relevant doses and offer an additional experimental paradigm for the NObonomic analysis of NO-donor metabolism and signaling.

Enhanced expression of intranuclear NF-kappa B in primed polymorphonuclear leukocytes in systemic inflammatory response syndrome patients.

Nuclear factor-kappa B (NF-kappa B) plays a critical role in the cellular response to a variety of stimuli, and it regulates the production of various inflammatory cytokines, adhesion molecules, and enzymes. Polymorphonuclear leukocytes (PMNLs) play a central role in systemic inflammatory response after severe insult. The role of NF-kappa B in activation of PMNLs, however, has not been clear. We developed a simple flow cytometric method for quantifying expression of intranuclear NF-kappa B in PMNLs, and we used it to evaluate NF-kappa B activity in patients with systemic inflammatory response syndrome (SIRS). Thirty patients who fulfilled the criteria for SIRS and 24 healthy volunteers were included as study subjects. Expression of intranuclear NF-kappa B with and without stimulation by lipopolysaccharide was quantified by our new method. Oxidative activity in PMNLs with and without formylmethionyl-leucyl-phenylalanine stimulation was measured by flow cytometry. Levels of interleukin-6, interleukin-8, PMNL elastase, and nitric oxide metabolites in blood were also measured. Expression of intranuclear NF-kappa B in PMNLs both with and without LPS stimulation was significantly elevated in SIRS patients in comparison with that of healthy volunteers. PMNL oxidative activity was significantly elevated in SIRS patients. Positive correlation was observed between intranuclear NF-kappa B expression and PMNL oxidative activity, whereas no relation was observed between intranuclear NF-kappa B expression and serum concentrations of chemical mediators. Our new flow cytometric method proved useful for quantifying intranuclear NF-kappa B expression in PMNLs. In PMNLs from SIRS patients, intranuclear NF-kappa B expression and oxidative activity were significantly elevated with positive correlation, and enhanced expression of NF-kappa B may play an important role in PMNL activation in SIRS.