Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.3.1 (NADPH oxidase)
 11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the role of reactive oxygen species in ozone-induced airway hyperresponsiveness (AHR) in Brown Norway rats. Airway responsiveness to inhaled acetylcholine (ACh) and bradykinin (BK) and inflammatory cell recruitment in bronchoalveolar lavage fluid (BALF) were measured in vivo. Neutral endopeptidase (NEP) activity assay and measurement of BK-receptor binding sites in Brown Norway rat lungs were carried out in vitro. Apocynin (5 mg/kg), an inhibitor of superoxide anion-generating NADPH oxidase, was administered perorally 30 min before a 3- or 6-h exposure to 3 ppm of ozone, and the animals were studied 18-24 h postexposure. Ozone induced increases in airway responsiveness to ACh and BK and in neutrophil counts in BALF. Apocynin inhibited the increase in airway responsiveness to BK but not to ACh without affecting the neutrophil counts in BALF. The antioxidants allopurinol and deferoxamine prevented ozone-induced AHR to both ACh and BK but did not reduce neutrophil counts. To further examine the mechanisms of ozone-induced AHR to BK, we measured NEP activity and the density of BK receptors in vitro after ozone exposure. Ozone exposure had no significant effect either on NEP activity or on the affinity and the number of BK receptors in lungs from rats treated with or without apocynin. We conclude that superoxide anions released from inflammatory cells in the airway may be involved in ozone-induced AHR. Inactivation of NEP or upregulation of BK receptors do not appear to be involved, but the possibility of localized changes cannot be excluded.
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PMID:Ozone-induced airway hyperresponsiveness: role of superoxide anions, NEP, and BK receptors. 777 93

We investigated the role of endogenous nitric oxide (NO) and superoxide anions in recombinant human interleukin-1 beta (rhIL-1 beta)-induced bronchial hyperresponsiveness (BHR) and neutrophilia in Brown-Norway rats. Aminoguanidine (100 mg/kg/d) administered subcutaneously for 3 d, an inhibitor of inducible NO synthase, L-arginine (100 mg/kg/d administered subcutaneously for 3 d, a specific precursor for the synthesis of NO, and apocynin (5 mg/kg/orally), an inhibitor of superoxide anion (O2-)-generating NADPH oxidase in macrophages and neutrophils, were administered prior to administration of rhIL-1 beta (500 U) intratracheally. Aminoguanidine in addition to another inhibitor of NO synthase, NW-nitro-L-arginine methyl ester (L-NAME) 100 mg kg/d administered subcutaneously for 3 d augmented bronchial responsiveness to inhaled bradykinin (BK) but not to acetylcholine (ACh), an effect reversed by L-arginine. rhIL-1 beta-treated rats also demonstrated BHR to BK but not to ACh, associated with neutrophilia in bronchoalveolar lavage fluid (BALF). rhIL-1 beta-induced BHR and neutrophilia were neither further increased by aminoguanidine nor inhibited by L-arginine. Apocynin, however, significantly inhibited rhIL-1 beta-induced BHR but not the BALF neutrophilia. Suppression of NO generation and generation of O2- from macrophages and infiltrating neutrophils may be important in rhIL-1 beta-induced airway hyperresponsiveness to bradykinin.
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PMID:Role of nitric oxide and superoxide anions in interleukin-1 beta-induced airway hyperresponsiveness to bradykinin. 792 31

In response to formyl-Met-Leu-Phe (fMLP), human neutrophils (PMN) generate superoxide anion (O2-) by the enzyme complex NADPH oxidase. The modulation of phosphoinositide (PPI) turnover and the activation of phospholipases C (PLC) and D (PLD) have been shown to be early steps in the oxidative response of fMLP-stimulated PMN. Although the physiological nonapeptide bradykinin (BK) is involved in inflammation, its participation in PMN activation has not been properly studied. In this work, activation of signal transduction pathways that mediate the oxidative response, and the modulation of the NADPH oxidase activity by BK, are analyzed. A direct comparison between the signal transduction pathway induced by BK and fMLP is also made. BK was not able to elicit O2- production by PMN. Nevertheless, several signal transduction pathways associated with PMN activation were triggered by BK. The nonapeptide induced the phosphorylation of prelabeled membrane PPI. This phenomenon was imitated by PMA and inhibited by H7 and staurosporine, thus suggesting the participation of protein kinase c (PKC). A loss of labeled [32P]PPI was triggered by fMLP. The fact that both PMA and fMLP stimulated O2- production but modulated PPI turnover in different ways, indicates that PPI labeling does not correlate with the oxidative response. Because PKC activation seemed to be a prerequisite for BK-induced modulation of PPI turnover, PLC activation could act as an intermediate step in this mechanism. Our results show that BK activated a PIP2-PLC measured as the release of [3H]IP3. On the contrary, a PC-PLD was highly stimulated by fMLP but not by BK. The fact that BK induced PLC activity but neither that of PLD nor NADPH oxidase, whereas fMLP triggered the activation of both phospholipases and evoked the PMN respiratory burst, suggests that diacylglycerol (DAG) from PIP2 as well as PA or PA-derived DAG, synergize to trigger the PMN oxidative response. Finally, BK inhibited O2- production by fMLP-activated PMN in a time-dependent manner. Since BK did not induce NO production by PMN, the inhibitory effect on the oxidative function was not due to ONOO- formation. These data show that BK plays an important role in inflammation by modulating the PMN function.
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PMID:Bradykinin stimulates phosphoinositide turnover and phospholipase C but not phospholipase D and NADPH oxidase in human neutrophils. 861 9

1. The generation of superoxide anions (O2-) by intact pig coronary artery rings was measured using a lucigenin-enhanced chemiluminescence technique and a histochemical technique with Nitroblue Tetrazolium (NBT) staining. 2. Isolated arteries with intact endothelium generated O2- at a rate of 9.0 +/- 0.8 pmol min-1 (mg dry weight)-1; this rate was diminished by about 24% when the endothelium was removed. The NBT staining of arterial ring preparations showed formazan precipitation mainly in the intima. Arterial rings were pretreated with diethylthiocarbamate in order to inhibit Cu-Zn superoxide dismutase (SOD) activity which increased the O2- generation by 184 +/- 55% (n = 10; P < 0.01). Stimulation of protein kinase C with phorbol 12-myristate 13-acetate (5 microM) enhanced endothelium-dependent O2- generation by 136 +/- 20% (n = 19; P < 0.01). Neither stimulation with bradykinin or substance P, nor inhibition with NG-nitro-L-arginine methyl ester of endothelial nitric oxide synthase had a significant effect on O2- generation. In contrast, the inhibition of flavoproteins with diphenyliodonium decreased concentration-dependent O2- generation (IC50, 1.85 +/- 5.33 microM). Inhibition of tetrahydrobiopterin synthesis with 2,4-diamino-6-hydroxy-pyrimidine resulted in a reduced generation of O2- by about 55%. 3. The addition of 100 microM NADH and 100 microM NADPH resulted in an excessive generation of O2- at a rate of 0.68 +/- 0.03 and 0.26 +/- 0.01 nmol O2- min-1 (mg protein)-1, respectively, in the membrane fraction, but not in the cytosolic fraction, of homogenates obtained from arteries. 4. The results suggest that intact coronary arteries do generate O2- under basal conditions and that the endothelial layer significantly contributes to this phenomenon. This generation of O2- is greatly influenced by intrinsic SOD activity. It is suggested that basal vascular O2- generation is mainly due to membrane-bound NAD(P)H oxidase activity and/or tetrahydrobiopterin-dependent processes.
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PMID:Endothelial-derived superoxide anions in pig coronary arteries: evidence from lucigenin chemiluminescence and histochemical techniques. 914 21

Endothelial nitric-oxide synthase (type III) (eNOS) was reported to form an inhibitory complex with the bradykinin receptor B2 (B2R) from which the enzyme is released in an active form upon receptor activation (Ju, H., Venema, V. J., Marrero, M. B., and Venema, R. C. (1998) J. Biol. Chem. 273, 24025-24029). Using a synthetic peptide derived from the known inhibitory sequence of the B2R (residues 310-329) we studied the interaction of the receptor with purified eNOS and neuronal nitric-oxide synthase (type I) (nNOS). The peptide inhibited formation of L-citrulline by eNOS and nNOS with IC(50) values of 10.6 +/- 0.4 microM and 7.1 +/- 0.6 microM, respectively. Inhibition was not due to an interference of the peptide with L-arginine or tetrahydrobiopterin binding. The NADPH oxidase activity of nNOS measured in the absence of L-arginine was inhibited by the peptide with an IC(50) of 3.7 +/- 0.6 microM, but the cytochrome c reductase activity of the enzyme was much less susceptible to inhibition (IC(50) >0.1 mM). Steady-state absorbance spectra of nNOS recorded during uncoupled NADPH oxidation showed that the heme remained oxidized in the presence of the synthetic peptide consisting of amino acids 310-329 of the B2R, whereas the reduced oxyferrous heme complex was accumulated in its absence. These data suggest that binding of the B2R 310-329 peptide blocks flavin to heme electron transfer. Co-immunoprecipitation of B2R and nNOS from human embryonic kidney cells stably transfected with human nNOS suggests that the B2R may functionally interact with nNOS in vivo. This interaction of nNOS with the B2R may recruit the enzyme to allow for the effective coupling of bradykinin signaling to the nitric oxide pathway.
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PMID:Interaction of endothelial and neuronal nitric-oxide synthases with the bradykinin B2 receptor. Binding of an inhibitory peptide to the oxygenase domain blocks uncoupled NADPH oxidation. 1068 1

Bradykinin stimulates proliferation of aortic vascular smooth muscle cells (VSMCs). We investigated the action of bradykinin on the phosphorylation state of the mitogen-activated protein kinases p42(mapk) and p44(mapk) in VSMCs and tested the hypothesis that reactive oxygen species (ROS) might be involved in the signal transduction pathway linking bradykinin activation of nuclear transcription factors to the phosphorylation of p42(mapk) and p44(mapk). Bradykinin (10(-8) mol/L) rapidly increased (4- to 5-fold) the phosphorylation of p42(mapk) and p44(mapk) in VSMCs. Preincubation of VSMCs with either N-acetyl-L-cysteine and/or alpha-lipoic acid significantly decreased bradykinin-induced cytosolic and nuclear phosphorylation of p42(mapk) and p44(mapk). In addition, the induction c-fos mRNA levels by bradykinin was completely abolished by N-acetyl-L-cysteine and alpha-lipoic acid. Using the cell-permeable fluorescent dye dichlorofluorescein diacetate, we determined that bradykinin (10(-8) mol/L) rapidly increased the generation of ROS in VSMCs. The NADPH oxidase inhibitor diphenylene iodonium (DPI) blocked bradykinin-induced c-fos mRNA expression and p42(mapk) and p44(mapk) activation, implicating NADPH oxidase as the source for the generation of ROS. These findings demonstrate that the phosphorylation of cytosolic and nuclear p42(mapk) and p44(mapk) and the expression of c-fos mRNA in VSMCs in response to bradykinin are mediated via the generation of ROS and implicate ROS as important mediators in the signal transduction pathway through which bradykinin promotes VSMC proliferation in states of vascular injury.
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PMID:Role of reactive oxygen species in bradykinin-induced mitogen-activated protein kinase and c-fos induction in vascular cells. 1077 66

In the porcine coronary artery, a cytochrome P450 (CYP) isozyme homologous to CYP 2C8/9 has been identified as an endothelium-derived hyperpolarizing factor (EDHF) synthase. As some CYP enzymes are reported to generate reactive oxygen species (ROS), we hypothesized that the coronary EDHF synthase may modulate vascular homeostasis by the simultaneous production of ROS and epoxyeicosatrienoic acids. In bradykinin-stimulated coronary arteries, antisense oligonucleotides against CYP 2C almost abolished EDHF-mediated responses but potentiated nitric oxide (NO)-mediated relaxation. The selective CYP 2C9 inhibitor sulfaphenazole and the superoxide anion (O(2-)) scavengers Tiron and nordihydroguaretic acid also induced a leftward shift in the NO-mediated concentration-relaxation curve to bradykinin. CYP activity and O(2-) production, determined in microsomes prepared from cells overexpressing CYP 2C9, were almost completely inhibited by sulfaphenazole. Sulfaphenazole did not alter the activity of either CYP 2C8, the leukocyte NADPH oxidase, or xanthine oxidase. ROS generation in coronary artery rings, visualized using either ethidium or dichlorofluorescein fluorescence, was detected under basal conditions. The endothelial signal was attenuated by CYP 2C antisense treatment as well as by sulfaphenazole. In isolated coronary endothelial cells, bradykinin elicited a sulfaphenazole-sensitive increase in ROS production. Although 11,12 epoxyeicosatrienoic acid attenuated the activity of nuclear factor-kappaB in cultured human endothelial cells, nuclear factor-kappaB activity was enhanced after the induction or overexpression of CYP 2C9, as was the expression of vascular cell adhesion molecule-1. These results suggest that a CYP isozyme homologous to CYP 2C9 is a physiologically relevant generator of ROS in coronary endothelial cells and modulates both vascular tone and homeostasis.
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PMID:Endothelium-derived hyperpolarizing factor synthase (Cytochrome P450 2C9) is a functionally significant source of reactive oxygen species in coronary arteries. 1113 72

Recently, it has been shown that the exogenous addition of hydrogen peroxide (H(2)O(2)) increases endothelial nitric oxide (NO(.)) production. The current study is designed to determine whether endogenous levels of H(2)O(2) are ever sufficient to stimulate NO(.) production in intact endothelial cells. NO(.) production was detected by a NO(.)-specific microelectrode or by an electron spin resonance spectroscopy using Fe(2+)-(DETC)(2) as a NO(.)-specific spin trap. The addition of H(2)O(2) to bovine aortic endothelial cells caused a potent and dose-dependent increase in NO(.) release. Incubation with angiotensin II (10(-7) mol) elevated intracellular H(2)O(2) levels, which were attenuated with PEG-catalase. Angiotensin II increased NO(.) production by 2-fold, and this was prevented by Losartan and by PEG-catalase, suggesting a critical role of AT1 receptor and H(2)O(2) in this response(.) In contrast, NO(.) production evoked by either bradykinin or calcium ionophore was unaffected by PEG-catalase. As in bovine aortic endothelial cells, angiotensin II doubled NO(.) production in aortic endothelial cells from C57BL/6 mice but had no effect on NO(.) production in endothelial cells from p47(phox-/-) mice. In contrast, stimulated NO(.) production to a similar extent in endothelial cells from wild-type and p47(phox-/-) mice. In summary, the present study provides direct evidence that endogenous H(2)O(2), derived from the NAD(P)H oxidase, mediates endothelial NO(.) production in response to angiotensin II. Under disease conditions associated with elevated levels of angiotensin II, this response may represent a compensatory mechanism. Because angiotensin II also stimulates O(2)() production from the NAD(P)H oxidase, the H(2)O(2) stimulation of NO(.) may facilitate peroxynitrite formation in response to this octapeptide.
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PMID:NAD(P)H oxidase-derived hydrogen peroxide mediates endothelial nitric oxide production in response to angiotensin II. 1237 64

Nitric oxide degradation linked to endothelial dysfunction plays a central role in cardiovascular diseases. Superoxide producing enzymes such as NADPH oxidase and xanthine oxidase are responsible for NO degradation as they generate a variety of reactive oxygen species (ROS). Moreover, superoxide is rapidly degraded by superoxide dismutase to produce hydrogen peroxide leading to the uncoupling of NO synthase and production of increased amount of superoxide. Angiotensin II is an important stimulus of NADPH oxidase. Through its AT(1) receptor, Ang II stimulates the long-term increase of several membrane component of NADPH oxidase such as P(22) phox or nox-1 and causes an increased activity of NADPH oxidase with inactivation of NO leading to impaired endothelium-dependent vasorelaxation, vascular smooth muscle cell hypertrophy, proliferation and migration, extracellular matrix formation, thrombosis, cellular infiltration and inflammatory reaction. Several preclinical and clinical studies have now confirmed the involvement of the AT(1) receptor in endothelial dysfunction. It is proposed that the AT(2) receptor counterbalances the deleterious effect of the Ang II-induced AT(1) receptor stimulation through bradykinin and NOS stimulation. This mechanism could be especially relevant in pathological cases when the NADPH oxidase activity is blocked with an AT(1) receptor antagonist.
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PMID:Angiotensin II and nitric oxide interaction. 1237 20

Intravital microscopic techniques were used to examine the mechanisms underlying bradykinin-induced leukocyte/endothelial cell adhesive interactions (LECA) and venular protein leakage (VPL) in single postcapillary venules of the rat mesentery. The effects of bradykinin superfusion to increase LECA and VPL were prevented by coincident topical application of either a bradykinin-B(2) receptor antagonist, a cell-permeant superoxide dismutase (SOD) mimetic or antioxidant, or inhibitors of cytochrome P-450 epoxygenase (CYPE) or protein kinase C (PKC) but not by concomitant treatment with either SOD, a mast cell stabilizer, or inhibitors of nitric oxide synthase, cyclooxygenase, xanthine oxidase, NADPH oxidase, or platelet-activating factor. Immunoneutralizing P-selectin or intercellular adhesion molecule-1 (ICAM-1) completely prevented bradykinin-induced leukocyte adhesion and emigration but did not affect VPL. On the other hand, stabilization of F-actin with phalloidin prevented bradykinin-induced leukocyte emigration and VPL but did not alter leukocyte adhesion. These data indicate that bradykinin induces LECA in rat mesenteric venules via a B(2)-receptor-initiated, CYPE-, oxidant- and PKC-mediated, P-selectin- and ICAM-1-dependent mechanism. Bradykinin also produced VPL, an effect that was initiated by stimulation of B(2) receptors and involved CYPE and PKC activation, oxidant generation, and cytoskeletal reorganization but was independent of leukocyte adherence and emigration.
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PMID:Bradykinin-induced proinflammatory signaling mechanisms. 1238 46


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