Higher Nitric Oxide Production Research Articles

Association of Sodium Induced High Blood Pressure with Up-Regulation of Inducible Nitric Oxide Synthase (iNOS) Expression and Inhibition of Trimethylation of H3K27 on Its Promoter Region

Nitric oxide (NO), a simple molecule, playing very diverse roles in the regulation of the cardiovascular, immunologic and nervous system, is formed from L-arginine by converting it to L-citrulline via nitric oxide synthase enzymes (NOS) including endothelial NOS (eNOS), neuronal NOS (nNOS) and inducible NOS (iNOS). We previously reported that long term inhibition of iNOS by intravenous administration of aminogunidine (AG) led to an aggravation of hypertension induced by high sodium chloride (NaCl) loading. Also, high blood pressure induced by high NaCl loading is associated with higher NO production in SD rats. The goal of the present study was to clarify whether the change of blood pressure alter iNOS gene expression as well as epigenetic modification of iNOS gene promoter region. Up-regulation of iNOS mRNA and protein were observed in renal medullary tissue of high sodium infused rats. Furthermore, chromatin immunoprecipitation assay evidenced the inhibition of recruitment of methyltransferase enhancer of Zeste homology 2 (EZH2) to, and trimethylation of histone 3 (H3) at lysine 27 (K27) of iNOS gene promoter region. We concluded that blood pressure is a regulator of iNOS gene expression through alteration of histone covalent modification of its genomic DNA.

Efeito do treinamento físico moderado e intenso sobre os mecanismos de defesa de ratos adultos

OBJETIVO: Analisou-se o impacto do treinamento físico moderado (TFM) e intenso (TFI) sobre o perfil leucocitário e a atividade microbicida de macrófagos alveolares, em 29 ratos machos Wistar. MÉTODOS: Foram formados três grupos: controle-sedentário (CS), treino-moderado (TM) e treino-intenso (TI). Os TFM e TFI foram efetuados através da natação, com aumento progressivo de carga conforme o peso corporal, até um máximo de 3% para o TFM, e 5% para o TFI. As coletas de sangue para contagem total e diferencial dos leucócitos foram automatizadas através do analisador hematológico Sysmex XT- 1800i (Roche®) antes e após o treino. E ao final realizou-se o lavado broncoalveolar para determinar a taxa de fagocitose e a produção de óxido nítrico (ON) de macrófagos. RESULTADOS: O grupo TM apresentou valores maiores para o número de leucócitos (12,77±2,0 x 17,25±2,4 10³/mm³), linfócitos (8,87±1,0 x 12,5±2,1 10³/mm³) e neutrófilos (0,99±0,5 x 3,18±1,0 10³/mm³), p<0,05. Apresentou também uma maior produção de ON (15,77±4,9µmols/mL) e da taxa de fagocitose (38,6%±8,65) em relação ao CS (6,58±1,9µmols/mL e 24,4%±7,40, respectivamente). Enquanto que, o grupo TI apresentou menor taxa de fagocitose (13,1%±1,52 x 24,4%±7,40), maior produção de ON (38,40± 2,1x 6,58±1,9 µmols/mL) e aumento apenas, no valor dos neutrófilos (2,6±1,4x 0,99±0,5 10³/mm³) quando comparado ao CS, p<0,001. CONCLUSÕES: O TFM proporcionou melhora nos mecanismos de defesa dos animais adultos. Enquanto que o TFI reduziu a taxa de fagocitose o que poderá implicar em prejuízo da atividade microbicida dos animais.

Cytokines Expression and Nitric Oxide Production under Induced Infection to Salmonella Typhimurium in Chicken Lines Divergently Selected for Cutaneous Hypersensitivity.

In the present study, the impact of Salmonella Typhimurium on cell-mediated immunity (CMI) was investigated in 5 week-old immuno divergent broiler lines selected for the high and low response to phytohemagglutinin-P. The immune response was assessed in peripheral-blood mononuclear cells (PBMCs) induced with Salmonella Typhimurium at different time intervals (0 h, 0.5 h, 2 h, 4 h, 6 h, 12 h and 24 h). The differential mRNA expression patterns of IFN-γ, IL-2 and iNOS were evaluated by quantitative real time PCR. In-vitro production of nitric oxide (NO) was also estimated in the culture supernatant and correlated with iNOS mRNA expression. Present study showed higher production of NO in the high cell-mediated line (HCMI) as compared to the low cell-mediated line (LCMI) upon stimulation with Salmonella Typhimurium. Correspondingly, higher mRNA expression of iNOS and IFN-γ were observed in high response birds (HCMI); but IL-2 was down regulated in this line compared to the low response birds (LCMI). Significantly (p<0.05) higher expression of iNOS, IFN-γ and higher production of NO in high line indicated that the selection for PHA-P response might be employed for increasing the immune competence against Salmonella Typhimurium in chicken flocks.

Effects of in ovo interleukin-4-plasmid injection on anticoccidia immune response in a coccidia infection model of chickens

Two experiments were conducted to study the effects of an in ovo interleukin (IL)-4 plasmid injection in a coccidia infection model. In experiment I, chicks were hatched from eggs that had been injected in ovo with an empty vector or with 10 or 15 μg of IL-4 plasmid, and then challenged posthatch with coccidia. In experiment II, chicks were hatched from eggs that had been vaccinated with coccidia and injected in ovo with an empty vector or with 10 or 15 μg of IL-4 plasmid, and then challenged posthatch with coccidia. In experiment II, the BW gain of birds hatched from eggs vaccinated with live oocysts plus 15 μg of IL-4 plasmid was 25% higher than the BW gain of birds hatched from eggs vaccinated with live oocysts plus empty plasmid. In both experiments I and II, a 15-μg IL-4-plasmid injection decreased fecal oocyst shedding, decreased the number of CD8(+) cells in the cecal tonsils, and decreased cecal tonsil lymphocyte cell proliferation postcoccidia challenge. In experiment I, splenic macrophages of chicks hatched from eggs injected with 15 μg of IL-4 plasmid had higher nitric oxide production than those of chicks hatched from eggs injected with the empty plasmid. In experiment II, a 15-μg IL-4-plasmid injection increased serum anticoccidia IgG postcoccidia challenge. It could be concluded that 15 μg of IL-4 plasmid improved anticoccidia immune responses synergistically with in ovo coccidia vaccination in chickens.

Evaluation of Solid-State Fermentation by Ganoderma lucidum Using Soybean Curd Residue

The effects of fermentation conditions on the production of polysaccharides from Ganoderma lucidum using soybean curd residue (SCR) as a substrate were investigated. Based on the optimum conditions of solid-state fermentation, the fermentation time, the inoculum size, and the C/N ratio were optimized by response surface methodology. The optimal fermentation conditions for G. lucidum polysaccharide were determined to be the following: 14.53 % of the inoculum size, 10.49 of the C/N ratio, and 21.18 days incubation. The maximum polysaccharide yield of 48.14 ± 1.47 mg/g was obtained in the verification experiment. Furthermore, treatment with 20 μg/mL of G. lucidum polysaccharide from fermented SCR showed significant stimulation for the macrophage proliferation and higher nitric oxide production. Compared with the unfermented soybean curd residue, the total phenolic compounds increased fourfold, and various amino acids were increased significantly in the fermented soybean curd residue. Therefore, a nutritious functional food or food additives could be produced using fermented soybean curd residue.

Overexpression of a Medicago truncatula stress-associated protein gene (MtSAP1) leads to nitric oxide accumulation and confers osmotic and salt stress tolerance in transgenic tobacco

The impact of Medicago truncatula stress-associated protein gene (MtSAP1) overexpression has been investigated in Nicotiana tabacum transgenic seedlings. Under optimal conditions, transgenic lines overexpressing MtSAP1 revealed better plant development and higher chlorophyll content as compared to wild type seedlings. Interestingly, transgenic lines showed a stronger accumulation of nitric oxide (NO), a signaling molecule involved in growth and development processes. This NO production seemed to be partially nitrate reductase dependent. Due to the fact that NO has been also reported to play a role in tolerance acquisition of plants to abiotic stresses, the responses of MtSAP1 overexpressors to osmotic and salt stress have been studied. Compared to the wild type, transgenic lines were less affected in their growth and development. Moreover, NO content in MtSAP1 overexpressors was always higher than that detected in wild seedlings under stress conditions. It seems that this better tolerance induced by MtSAP1 overexpression could be associated with this higher NO production that would enable seedlings to reach a high protection level to prepare them to cope with abiotic stresses.

Nitric oxide (NO) — Production and regulation of insulin secretion in islets of freely fed and fasted mice

Production of nitric oxide through the action of nitric oxide synthase (NOS) has been detected in the islets of Langerhans. The inducible isoform of NOS (iNOS) is induced by cytokines and might contribute to the development of type-1 diabetes, while the constitutive isoform (cNOS) is thought to be implicated in the physiological regulation of insulin secretion. In the present study we have detected and quantified islet cNOS- and iNOS-derived NO production concomitant with measuring its influence on insulin secretion in the presence of different secretagogues: glucose, l-arginine, l-leucine and α-ketoisocaproic acid (KIC) both during fasting and freely fed conditions. In intact islets from freely fed mice both cNOS- and iNOS-activity was greatly increased by glucose (20mmol/l). Fasting induced islet iNOS activity at both physiological (7mmol/l) and high (20mmol/l) glucose concentrations. NOS blockade increased insulin secretion both during freely fed conditions and after fasting. l-arginine stimulated islet cNOS activity and did not affect islet iNOS activity. l-leucine or KIC, known to enter the TCA cycle without affecting glycolysis, did not affect either islet cNOS- or iNOS activity. Accordingly, insulin secretion stimulated by l-leucine or KIC was unaffected by addition of l-NAME both during feeding and fasting. We conclude that both high glucose concentrations and fasting increase islet total NO production (mostly iNOS derived) which inhibit insulin secretion. The insulin secretagogues l-leucine and KIC, which do not affect glycolysis, do not interfere with the islet NO–NOS system.

The effect of extracted bacterial LPS from Salmonella enteritidis on COX-2 in hepg2 cell line in induction and inhibition conditions

Hepatocellular carcinoma is the fifth most common neoplasm and the most important cause of death in patients with liver cirrhosis in the world. lipopolysaccharide (LPS) stimulates the hepatocyte cells and increases the production of inducible cytokine with the high production of nitric oxide and ROS. Chronic inflammation caused by lipopolysaccharide directly activates immune system and indirectly, through COX-2 interferes in the formation of malignant disease. In this study, the rate change of COX-2 was searched by adding LPS and also the effect of inhibition of this inflammatory enzyme by Celecoxib and combined effect of this in HepG2 cancer cells was assessed. Salmonellaenteritidis lipopolysaccharide is extracted by methanol-chloroform method and the Sodium dodesyl sulfate poly acryl-amide gel electrophoresis (SDS-PAGE) electrophoresis bands were stained by silver nitrate. Four treatment groups of HepG2 cells were stimulated with 100 ng/ml LPS, 500 µM Celecoxib as inhibitor and were incubated for 12 and 24 h. Variables including both increase and decrease inflammatory factor, COX-2, was assayed. The obtained results showed that initial activity of COX-2 in not stimulated in HepG2 cell, 1.957 ng/ml after stimulation with LPS for 12 and 24 h (1.383 and 0.618 ng/ml) decreased and the effect of this inhibitor was also studied. The data showed that the reduction of COX-2 in HepG2 cells was correlated with the cell density and duration of incubation with LPS. Inhibition of enzyme associated with inflammation, with inhibitor substance; celecoxib, observed as well as LPS. We can potentially design drugs to treat a variety of diseases and cancers. Key words: Cyclooxygenase-2, HepG2 Cell, Salmonella enteritidis,lipopolysaccharide, Sodium dodesyl sulfate poly acryl-amide gel electrophoresis (SDS-PAGE).

Immunostimulatory and cytotoxic activities of Indigofera suffruticosa (Fabaceae)

One of the major disadvantages of the current cancer therapy is the suppression of the immune system. Brazilian flora is considered one of the most diverse in the world and many plants were found to contain active constituents that can be valuable sources of new drugs. The plant Indigofera suffruticosa was studied to determine its potential to stimulate the immune system and also to be effective against tumour cells. We investigated the effects of the alkaloidal fraction and the pure alkaloid indigo obtained from I. suffruticosa on macrophage activation by measuring nitric oxide (NO) and tumour necrosis factor-α (TNF-α) production. Cytotoxic activity was also evaluated against the two tumour murine cells lines, LM2 (breast adenocarcinoma) and LP07 (lung adenocarcinoma). The alkaloidal fraction induced a high NO production and a moderated TNF-α release. The pure indigo demonstrated an elevated NO and TNF-α production. The fraction and the pure compound also exhibited cytotoxic activity against both adenocarcinoma cell lines and indigo showed the strongest cytotoxic activity with IC50 value of 0.89 µg mL−1 against LM2 and 1.44 µg mL−1 against LP07. Our results presented the immunostimulatory and cytotoxic activity of I. suffruticosa, enhancing macrophage function and therefore contributing to the host defence against tumours.

Nitric oxide formation by lymphatic bulb and valves is a major regulatory component of lymphatic pumping

Microscopic lymphatics produce nitric oxide (NO) during contraction as flow shear activates the endothelial cells. The valve leaflets and bulbous valve housing contain a large amount of endothelial nitric oxide synthase (eNOS) due both to many endothelial cells and increased expression of eNOS. Direct NO measurements indicate the valve area has a 30-50% higher NO concentration ([NO]) than tubular regions although both regions generate equivalent relative increases in [NO] with each contraction. We hypothesize that 1) the greater eNOS and [NO] of the bulb region would have greater effects to lower pumping activity of the overall lymphatic than occurs in tubular regions and 2), the elevated [NO] in the bulb region may be because of high NO production in the valve leaflets that diffuses to the wall of the bulb. Measurement of [NO] with a micropipette inside the lymphatic bulb revealed the valve leaflets generate ~50% larger [NO] than the bulb wall in the in vivo rat mesenteric lymphatics. The valves add NO to the lymph that quickly diffuses to the bulb wall. Bradykinin locally released iontophoretically from a micropipette on both bulbs and tubes increased the [NO] in a dose-dependent manner up to ~50%, demonstrating agonist activation of the NO pathway. However, pumping output determined by contraction frequency and stroke volume decreased much more for the bulb than tubular areas in response to the bradykinin. In effect, NO generation by the bulb area and its valves limits the pumped flow of the total lymphatic by lowering frequency and stroke volume of individual contractions.

Interferon-γ and Nitric Oxide Production During Behçet Uveitis: Immunomodulatory Effect of Interleukin-10

Uveitis is one of the major manifestations of Behçet Disease, a systemic inflammatory vasculitis. Our aim is to investigate in vivo and in vitro production of interferon (IFN)-γ and nitric oxide (NO) during Behçet uveitis (BU). Moreover, we evaluated the implication of IFN-γ and interleukin (IL)-10 in the regulation of NO production in vitro. Cytokines' concentrations were measured by ELISA, and NO levels were assessed by modified Griess's method. Our results showed that patients with active disease had significant elevation of IFN-γ and NO concentrations in both plasma and peripheral blood mononuclear cell culture supernatants compared with controls (P<0.01) or to patients with inactive disease (P<0.05). Further, IFN-γ induced significantly higher production of NO in cell culture supernatants, whereas IL-10 significantly reduced it (P<0.05). In conclusion, the elevated levels of IFN-γ in vivo and in vitro in patients with BU reflect the implication of this cytokine in the disease physiopathology. These results suggest that IFN-γ, through the induction of NO synthase 2 and the production of NO, is implicated in the genesis of the inflammatory process during active BU; whereas IL-10 seems to have protective properties.

Innate response of human endothelial cells infected with mycobacteria

Endothelial cells are susceptible to infection by several pathogens, but little is known about mycobacterial infection. We analyzed some features of mycobacteria–endothelial cell interactions and the innate response to the infection. Intracellular growth in human umbilical vein endothelial cells (HUVECs) of three Mycobacterium species: M. tuberculosis (MTB), M. abscessus (MAB) and M. smegmatis (MSM) was analyzed. M. smegmatis was eliminated; M. abscessus had an accelerate intracellular replication and M. tuberculosis did not replicate or was eliminated. M. abscessus infection induced profound cytoskeleton rearrangements, with M. tuberculosis infection changes were less marked, and with MSM were slight. Nitric oxide (NO) production was induced differentially: M. abscessus induced the highest levels followed by M. tuberculosis and M. smegmatis; the contrary was true for reactive oxygen species (ROS) production. Only M. tuberculosis infection caused beta-1 defensin over-expression. As a whole, our results describe some aspects of the innate response of HUVEC infected by mycobacteria with different virulence and suggest that a strong cytoskeleton mobilization triggers a high NO production in these cells.

Leishmania infantum: Lipophosphoglycan intraspecific variation and interaction with vertebrate and invertebrate hosts

Interspecies variations in lipophosphoglycan (LPG) have been the focus of intense study over the years due its role in specificity during sand fly-Leishmania interaction. This cell surface glycoconjugate is highly polymorphic among species with variations in sugars that branch off the conserved Gal(β1,4)Man(α1)-PO4 backbone of repeat units. However, the degree of intraspecies polymorphism in LPG of Leishmania infantum (syn. Leishmania chagasi) is not known. In this study, intraspecific variation in the repeat units of LPG was evaluated in 16 strains of L. infantum from Brazil, France, Algeria and Tunisia. The structural polymorphism in the L. infantum LPG repeat units was relatively slight and consisted of three types: type I does not have side chains; type II has one β-glucose residue that branches off the disaccharide-phosphate repeat units and type III has up to three glucose residues (oligo-glucosylated). The significance of these modifications was investigated during in vivo interaction of L. infantum with Lutzomyia longipalpis, and in vitro interaction of the parasites and respective LPGs with murine macrophages. There were no consequential differences in the parasite densities in sand fly midguts infected with Leishmania strains exhibiting type I, II and III LPGs. However, higher nitric oxide production was observed in macrophages exposed to glucosylated type II LPG.

Role of Nitric Oxide Signaling Pathways in Brain Injuries

Nitric oxide (NO) is involved in many physiological and pathological brain processes. NO is probably the smallest and most versatile bioactive molecule identified. NO signaling in excitable tissues requires rapid and controlled delivery of NO to specific cellular targets. This tight control of NO signaling is largely regulated at the level of its biosynthesis. NO production might lead either to toxicity or to neuroprotection depending on the level of NO, the location of NO production, the extent of oxidative stress and the type of neurodegenerative process. It has been suggested that NO directly acts as an antioxidant. This protective effect is mediated by small fluxes of NO ( < 1 μmol/L). This is consistent with the fact that NO terminates lipid peroxidation reactions and suggests that the production of NO is a major protective mechanism against oxidative stress in vivo. In fact it has been demonstrated, in vitro as well as in vivo, that during brain insult NO might be part of the physiological response to injury. In general, it is accepted that a normal pathophysiologic response of the damaged tissue may involve controlled NO production and the inhibition of this response may interfere with the normal repair process. Nevertheless, it has been suggested that a high production of NO after the induction of iNOS expression can interact with superoxide anion generated by the mitochondria or by other mechanisms, leading to the formation of the potent oxidant species peroxynitrite. These events would result in cell damage and altered neuronal physiological function. The present review focuses on the role of NO as an important neuromodulator that can exert both neurotoxic and neuroprotective effects in different injuries. Keywords: Brain injuries, chronic stress, intracellular signaling, neurotoxicity, neuroprotection, nitric oxide

Synthesis of New Quinoline Derivatives as Inhibitors of Human Tumor Cells Growth

A series of new 8-[(2H-tetrazol-5-yl)methoxy]quinoline derivatives, their sugar hydrazones, and their N-glycoside derivatives were synthesized. Furthermore, the 1,2,4-triazole-3-one derivatives 3 and 4 were synthesized from the amidrazone derivative 2. Some of the newly prepared compounds demonstrated inhibitory effects on the growth of MCF-7 human breast cancer cells as compared with the activity of the commonly used anticancer drug, cisplatin. The results of antitumor evaluation revealed that compounds 2-5, 8b, and 12 inhibited the growth of cancer cells through their effect as free-radical regulators by increasing the activity of superoxide dismutase and depletion of intracellular levels of reduced glutathione, catalase and glutathione peroxidase activities, accompanied with a high production of hydrogen peroxide, nitric oxide, and other free radicals causing the killing of tumor cells. The results suggested that the prepared compounds possess significant anticancer activity comparable to cisplatin and the antitumor activity of these prepared compounds was accompanied with a reduction in the levels of protein and nucleic acids.

The beneficial effect of small toxic molecules on dormancy alleviation and germination of apple embryos is due to NO formation

Deep dormancy of apple (Malus domestica Borkh.) seeds is terminated by a 3-month-long cold stratification. It is expressed by rapid germination of seeds and undisturbed growth of seedlings. However, stimulation of germination of isolated apple embryos is also observed after applying inhibitors of cytochrome c oxidase: nitric oxide (NO) or hydrogen cyanide (HCN) during the first 3-6 h of imbibition of dormant embryos. The aim of this work was to compare the effect of yet another toxic gaseous molecule carbon monoxide (CO) with the effects of HCN and NO on germination of apple embryos and growth and development of young seedlings. We demonstrated that stimulation of germination after short-term pre-treatment with HCN, NO or CO was accompanied by enhanced NO emission from the embryo axes during their elongation. Moreover, similarly high NO production from non-dormant embryos, after cold stratification, was detected. Therefore, we propose that NO may act as signaling molecule in apple embryo dormancy break.

Immunostimulatory Properties of a Polysaccharide Isolated fromAstraeus hygrometricus

Mushrooms have been used as food and for therapeutic purpose for decades, and various compounds derived from these have potential biological activities. Application of such agents of natural origin is vital with relevance to an increase in diseases involving immune dysfunction, cancer, and autoimmune conditions in recent years. These compounds belong mainly to polysaccharides, especially beta-D-glucan, glycopeptide/protein complexes, proteoglycans, proteins, and triterpenoids. Among these compounds, polysaccharides and their peptide/protein derivates have extremely important roles in immunomodulating activities. The present study aims to explore the immunomodulatory properties of polysaccharide isolated from the mushroom Astraeus hygrometricus. The polysaccharide isolated by hot alkaline extraction and chromatography was designated as AE2 and studied for its immunostimulatory potential in vivo in a murine model. Macrophages from treated mice showed higher production of nitric oxide and interleukin-1 and also exhibited an increased phagocytic potential. It also enhanced natural killer cell activation and proliferation of splenocytes with an increase in the T-helper (Th) 1 cytokine level of splenocyte culture supernatant. The cytokine level in serum also indicated a Th1 skew. The observed activities were associated with no general toxicity to the organism. The findings will be helpful in considering A. hygrometricus as a potential source of an immunomodulator and in designing further studies to understand its mode of action on immune system.

Indoleamine 2,3‐dioxigenase (IDO) is critical for host resistance againstTrypanosoma cruzi

Indoleamine 2,3-dioxygenase (IDO) is an inflammatory cytokine-inducible rate-limiting enzyme of the tryptophan (Trp) catabolism, which is involved in the inhibition of intracellular pathogen replication as well as in immunomodulation. Here we demonstrated the effect of IDO-dependent Trp catabolism on Trypanosoma cruzi resistance to acute infection. Infection with T. cruzi resulted in the systemic activation of IDO. The blocking of IDO activity in vivo impaired resistance to the infection and exacerbated the parasite load and infection-associated pathology. In addition, IDO activity was critical to controlling the parasite's replication in macrophages (Mos), despite the high production of nitric oxide produced by IDO-blocked T. cruzi-infected Mos. Analysis of the mechanisms by which IDO controls the parasite replication revealed that T. cruzi amastigotes were sensitive to L-kynurenine downstream metabolites 3-hydroxykynurenine (3-HK) and 3-hydroxyanthranilic acid, while 3-HK also affected the trypomastigote stage. Finally, 3-HK treatment of mice acutely infected with T. cruzi was able to control the parasite and to improve the survival of lethally infected mice. During infection, IDO played a critical role in host defense against T. cruzi; therefore, the intervention of IDO pathway could be useful as a novel antitrypanosomatid therapeutic strategy.

Preventive effects of propofol and ketamine on renal injury in unilateral ureteral obstruction

The aim of the present study was to investigate the preventive effects of propofol and ketamine as anesthetics on renal injury in unilateral ureteral obstruction (UO). Twenty-four male New Zealand white rabbits were randomly assigned to four groups of six rabbits each. Anesthesia was induced and maintained with propofol in groups 1 and 2 and with ketamine in groups 3 and 4. Groups 2 and 4 received complete left ureteral ligation. Groups 1 and 3 (control groups) underwent an identical surgical procedure without ureteral ligation. At 14 days of obstruction, animals were sacrificed and ipsilateral kidneys were removed for determination of tissue nitric oxide (NO) levels and immunohistochemical evaluation of endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), and apoptosis protease-activating factor 1 (APAF-1). Between groups 1 and 3, there were no differences in tissue NO levels and eNOS, iNOS, and APAF-1 expressions. iNOS and APAF-1 expressions were at the mild to moderate levels in group 2, but these parameters were markedly increased in group 4 at 14 days of obstruction. Also, elevated expression of iNOS was accompanied by a high NO production in group 4 compared with group 2. Although eNOS expressions were increased in both groups 2 and 4, there were no significant differences between these groups. Propofol as an anesthetic agent may attenuate NO-induced renal tubular cell apoptosis by downregulating the expression of iNOS in an animal model of unilateral UO.

Differential regulation of inducible and endothelial nitric oxide synthase by kinin B1 and B2 receptors

Kinins are vasoactive peptides that play important roles in cardiovascular homeostasis, pain and inflammation. After release from their precursor kininogens, kinins or their C-terminal des-Arg metabolites activate two distinct G protein-coupled receptors (GPCR), called B2 (B2R) or B1 (B1R). The B2R is expressed constitutively with a wide tissue distribution. In contrast, the B1R is not expressed under normal conditions but is upregulated by tissue insult or inflammatory mediators. The B2R is considered to mediate many of the acute effects of kinins while the B1R is more responsible for chronic responses in inflammation. Both receptors can couple to Galphai and Galphaq families of G proteins to release mediators such as nitric oxide (NO), arachidonic acid, prostaglandins, leukotrienes and endothelium-derived hyperpolarizing factor and can induce the release of other inflammatory agents. The focus of this review is on the different transduction events that take place upon B2R and B1R activation in human endothelial cells that leads to generation of NO via activation of different NOS isoforms. Importantly, B2R-mediated eNOS activation leads to a transient ( approximately 5min) output of NO in control endothelial cells whereas in cytokine-treated endothelial cells, B1R activation leads to very high and prolonged ( approximately 90min) NO production that is mediated by a novel signal transduction pathway leading to post-translational activation of iNOS.