Angiotensin II decreases inducible nitric oxide synthase expression in rat astroglial cultures

1995 ◽  
Vol 268 (3) ◽  
pp. C700-C707 ◽  
Author(s):  
L. J. Chandler ◽  
K. Kopnisky ◽  
E. Richards ◽  
F. T. Crews ◽  
C. Sumners
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Nitric Oxide Synthase ◽  
Receptor Antagonist ◽  
Maximal Response ◽  
No Production ◽  
Dependent Manner ◽  
Ang Ii ◽  
Subsequent Formation ◽  
Oxide Synthase

Consistent with stimulation of expression of an inducible form of nitric oxide synthase (iNOS), exposure of rat astroglial cultures to lipopolysaccharide (LPS) caused a time-dependent increase in the accumulation of nitrite in the culture media. Addition of the peptide angiotensin II (ANG II) with LPS decreased subsequent formation of nitrite in a concentration-dependent manner (concentration inhibiting 50% of maximal response approximately 1 nM). The ANG II effect could be blocked by the ANG II type 1 (AT1 receptor antagonist losartan but not by the ANG II type 2 (AT2) receptor antagonist PD-123177. ANG II had no effect on nitrite formation stimulated by a combination of inflammatory cytokines (interleukin-1 beta, tumor necrosis factor-alpha, and interferon-gamma). A brief 10-min exposure to ANG II was sufficient to cause an approximately 30% inhibition of the LPS response, with maximal inhibition of approximately 65% after 3 h, and occurred only when ANG II was added during the iNOS induction phase. Consistent with partial inhibition of LPS-stimulated expression of iNOS, ANG II reduced the levels of both iNOS mRNA and iNOS protein. These results demonstrate that ANG II can decrease LPS-stimulated NO production in astroglia by inhibiting induction of iNOS expression.

Endothelin stimulates endothelial nitric oxide synthase expression in the thick ascending limb

2004 ◽  
Vol 287 (2) ◽  
pp. F231-F235 ◽  
Author(s):  
Marcela Herrera ◽  
Jeffrey L. Garvin
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Receptor Antagonist ◽  
Endothelial Nitric Oxide Synthase ◽  
No Production ◽  
Thick Ascending Limb ◽  
Enos Expression ◽  
No Release ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Endothelin-1 (ET-1) acutely inhibits NaCl reabsorption by the thick ascending limb (THAL) by activating the ETB receptor, stimulating endothelial nitric oxide synthase (eNOS), and releasing nitric oxide (NO). In nonrenal tissue, chronic exposure to ET-1 stimulates eNOS expression via the ETB receptor and activation of phosphatidylinositol 3-kinase (PI3K). We hypothesized that ET-1 increases eNOS expression in the THAL by binding to ETB receptors and stimulating PI3K. In primary cultures of medullary THALs treated for 24 h, eNOS expression increased by 36 ± 18% with 0.01 nM ET-1, 123 ± 30% with 0.1 nM ( P < 0.05; n = 5), and 71 ± 30% with 1 nM, whereas 10 nM had no effect. BQ-788, a selective ETB receptor antagonist, completely blocked stimulation of eNOS expression caused by 0.1 nM ET-1 (12 ± 25 vs. 120 ± 40% for ET-1 alone; P < 0.05; n = 5). BQ-123, a selective ETA receptor antagonist, did not affect the increase in eNOS caused by 0.1 nM ET-1. Sarafotoxin c (S6c; 0.1 μM), a selective ETB receptor agonist, increased eNOS expression by 77 ± 30% ( P < 0.05; n = 6). Wortmannin (0.01 μM), a PI3K inhibitor, completely blocked the stimulatory effect of 0.1 μM S6c (77 ± 30 vs. −28 ± 9%; P < 0.05; n = 6). To test whether the increase in eNOS expression heightens activity, we measured NO release in response to simultaneous treatment with l-arginine, ionomycin, and clonidine using a NO-sensitive electrode. NO release by control cells was 337 ± 61 and 690 ± 126 pA in ET-1-treated cells ( P < 0.05; n = 5). Taken together, these data suggest that ET-1 stimulates THAL eNOS, activating ETB receptors and PI3K and thereby increasing NO production.

scholarly journals Effects of selected endothelium-dependent vasodilators on fetoplacental vasculature: physiological implications

1999 ◽  
Vol 277 (2) ◽  
pp. H842-H847
Author(s):  
Saral Amarnani ◽  
Belinda Sangrat ◽  
Gautam Chaudhuri
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Receptor Antagonist ◽  
Perfusion Pressure ◽  
Ang Ii ◽  
Hoe 140 ◽  
Oxide Synthase

The endothelium-dependent vasodilators ACh, histamine, and bradykinin were studied in the isolated, perfused human placental cotyledon. Histamine caused a decrease in perfusion pressure that was attenuated by cimetidine. Bradykinin, at lower concentrations (10−20 to 10−14 M), produced a concentration-dependent decrease in perfusion pressure, whereas at higher concentrations it produced an increase in perfusion pressure. ACh was without any effect. The decrease in perfusion pressure observed with bradykinin was potentiated by captopril and was significantly attenuated in the presence of HOE-140, the B2-receptor antagonist, or by pretreatment with an inhibitor of nitric oxide synthase, but not by an inhibitor of cyclooxygenase. The decrease in perfusion pressure observed with bradykinin was potentiated by ANG I but not by ANG II. It is concluded that endothelium-dependent vasodilation can be demonstrated with histamine and bradykinin in the fetoplacental vessels, and at least for bradykinin, this is partly mediated by release of nitric oxide. The potentiation of the bradykinin response in the presence of ANG I may serve to buffer the vasoconstriction produced by ANG II in the fetoplacental circulation.

Angiotensin II type 2 receptor-dependent increases in nitric oxide synthase expression in the pulmonary endothelium is mediated via a Gαi3/Ras/Raf/MAPK pathway

2007 ◽  
Vol 292 (6) ◽  
pp. C2185-C2196 ◽  
Author(s):  
Jianyu Li ◽  
Xiangmin Zhao ◽  
Xinmei Li ◽  
Kenneth M. Lerea ◽  
Susan C. Olson
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Nitric Oxide Synthase ◽  
Mapk Pathway ◽  
Dominant Negative ◽  
Ang Ii ◽  
Enos Expression ◽  
Src Tyrosine Kinase ◽  
Oxide Synthase

We have previously reported that angiotensin II (ANG II) stimulated Src tyrosine kinase via a pertussis toxin-sensitive type 2 receptor, which, in turn, activates MAPK, resulting in an increase in nitric oxide synthase (NOS) expression in pulmonary artery endothelial cells (PAECs). The present study was designed to investigate the pathway by which ANG II activates Src leading to an increase in ERK1/ERK2 phosphorylation and an increase in NOS protein in PAECs. Transfection of PAECs with Gαi3 dominant negative (DN) cDNA blocked the ANG II-dependent activation of Src, ERK1/ERK2 phosphorylation, and increase in NOS expression. ANG II stimulated an increase in tyrosine phosphorylation of sequence homology of collagen (Shc; 15 min) that was prevented when PAECs were pretreated with 4-amino-5-(4-chlorophenyl)-7-( t-butyl)pyrazolo-[3,4-d]pyrimidine (PP2), a Src inhibitor. ANG II induced a Src-dependent association between Shc and growth factor receptor-bound protein 2 (Grb2) and between Grb2 and son of sevenless (Sos), both of which were maximal at 15 min. The ANG II-dependent increase in Ras GTP binding was prevented when PAECs were pretreated with the AT2 antagonist PD-123319 or with PP2 or were transfected with Src DN cDNA. ANG II-dependent activation of MAPK and the increase in endothelial NOS (eNOS) were prevented when PAECs were transfected with Ras DN cDNA or treated with FTI-277, a farnesyl transferase inhibitor. ANG II induction of Raf-1 phosphorylation was prevented when PAECs were pretreated with PD-123319 and PP2. Raf kinase inhibitor 1 prevented the ANG II-dependent increase in eNOS expression. Collectively, these data suggest that Gαi3, Shc, Grb2, Ras, and Raf-1 link Src to activation of MAPK and to the AT2-dependent increase in eNOS expression in PAECs.

Lack of endothelial nitric oxide synthase decreases cardiomyocyte proliferation and delays cardiac maturation

2006 ◽  
Vol 291 (6) ◽  
pp. C1240-C1246 ◽  
Author(s):  
Erin Lepic ◽  
Dylan Burger ◽  
Xiangru Lu ◽  
Wei Song ◽  
Qingping Feng
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Brdu Incorporation ◽  
No Production ◽  
Dependent Manner ◽  
Cardiomyocyte Proliferation ◽  
Cell Counts ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

We recently demonstrated that deficiency in endothelial nitric oxide synthase (eNOS) results in congenital septal defects and postnatal heart failure. The aim of this study was to investigate the role of eNOS in cardiomyocyte proliferation and maturation during postnatal development. Cultured eNOS knockout (eNOS−/−) cardiomyocytes displayed fewer cells and lower bromodeoxyuridine (BrdU) incorporation in vitro compared with wild-type (WT) cardiomyocytes ( P < 0.05). Treatment with the nitric oxide (NO) donor diethylenetriamine NONOate increased BrdU incorporation and cell counts in eNOS−/− cardiomyocytes ( P < 0.05). Inhibition of nitric oxide synthase activity using NG-nitro-l-arginine methyl ester decreased the level of BrdU incorporation and cell counts in WT cardiomyocytes ( P < 0.05). Vascular endothelial growth factor (VEGF) increased the level of BrdU incorporation in cultured WT cardiomyocytes in a dose- and time-dependent manner ( P < 0.05). Conversely, VEGF did not alter BrdU incorporation in eNOS−/− cardiomyocytes ( P = not significant). Furthermore, deficiency in eNOS significantly decreased BrdU labeling indexes in neonatal hearts in vivo. Although WT hearts displayed a rapid decrease in atrial natriuretic peptide (ANP) expression in the first week of neonatal life, ANP expression in eNOS−/− hearts remain elevated. Our study demonstrated that NO production from eNOS is necessary for postnatal cardiomyocyte proliferation and maturation, suggesting that eNOS plays an important role during postnatal heart development.

scholarly journals Angiotensin II inhibits inducible nitric oxide synthase in tubular MCT cells by a posttranscriptional mechanism.

1997 ◽  
Vol 8 (4) ◽  
pp. 551-557 ◽  
Author(s):  
G Wolf ◽  
F N Ziyadeh ◽  
R Schroeder ◽  
R A Stahl
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Nitric Oxide Synthase ◽  
Ang Ii ◽  
Proximal Tubular Cells ◽  
Inos Protein ◽  
Tubular Cells ◽  
Inos Protein Expression ◽  
Proximal Tubular ◽  
Oxide Synthase

Expression of the inducible isoform of nitric oxide synthase (iNOS) and generation of nitric oxide (NO) have been recently described, in addition to mesangial and medullary thick ascending limb cells, in proximal tubular cells, including MCT, a mouse proximal tubular epithelium cell line. Because vasoconstrictors may interfere with the induction of iNOS and the subsequent generation of NO, in the study presented here, whether exogenous angiotensin II (ANG II) influences bacterial lipopolysaccharide (LPS)/gamma-interferon (gamma-IF)-stimulated NO synthesis and iNOS protein and mRNA expression in MCT cells was tested. LPS/gamma-IF readily stimulated nitrite synthesis in MCT cells, as one measured parameter of NO synthesis. Coincubation of cells with 10(-9)-10(-6) M ANG II attenuated this LPS/gamma-IF-stimulated induction of nitrite. This effect was reversed by the AT1-receptor blocker losartan, but not by an AT2-receptor antagonist, indicating signal transduction through AT1-receptors. Western blot analysis applying a specific monoclonal antibody generated against mouse iNOS revealed that 10(-8)-10(-6) M ANG II significantly reduced LPS/gamma-IF-induced iNOS protein expression. However, ANG II had no effect on LPS/gamma-IF-induced iNOS mRNA as assessed by Northern blots. Moreover, transient transfection studies using a chimeric gene construct, in which iNOS regulatory elements are linked to the CAT reporter gene, showed no effect of ANG II on the LPS/gamma-IF-stimulated transcriptional activity. The study presented here demonstrates that ANG II influences LPS/gamma-IF-stimulated NO generation in MCT cells, most likely at a posttranscriptional level, by influencing iNOS protein expression. Whether proximal tubular cells in vivo express iNOS remains to be established, but this study suggests a mechanism for how iNOS activity is influenced by ANG II in cultured proximal tubular cells.

scholarly journals Systemic Aldosterone, But Not Angiotensin II, Plays a Pivotal Role in the Pathogenesis of Renal Injury in Chronic Nitric Oxide-Deficient Male Rats

Endocrinology ◽  
2015 ◽  
Vol 156 (7) ◽  
pp. 2657-2666 ◽  
Author(s):  
Takaichi Suehiro ◽  
Kazuhiko Tsuruya ◽  
Hirofumi Ikeda ◽  
Jiro Toyonaga ◽  
Shunsuke Yamada ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Nitric Oxide Synthase ◽  
Renal Injury ◽  
Male Rats ◽  
Systemic Hypertension ◽  
Type I ◽  
Ang Ii ◽  
Aldosterone Antagonist ◽  
Oxide Synthase

Chronic inhibition of nitric oxide synthase by Nω-nitro-L-arginine methyl ester (L-NAME) causes progressive renal injury and systemic hypertension. Angiotensin II (Ang II) has been conventionally regarded as one of the primary causes of renal injury. We reported previously that such renal injury was almost completely suppressed by both an Ang II type I receptor blocker and an aldosterone antagonist. The aldosterone antagonist also inhibited the systemic Ang II elevation. Therefore, it remains to be elucidated whether Ang II or aldosterone directly affects the development of such renal injury. In the present study, we investigated the role of aldosterone in the pathogenesis of renal injury induced by L-NAME-mediated chronic nitric oxide synthase inhibition in male Wistar rats (aged 10 wk). Serial analyses demonstrated that the renal injury and inflammation in L-NAME-treated rats was associated with elevation of both Ang II and aldosterone. To investigate the direct effect of aldosterone on the renal injury, we conducted adrenalectomy (ADX) and aldosterone supplementation in L-NAME-treated rats. In ADX rats, aldosterone was undetectable, and renal injury and inflammation were almost completely prevented by ADX, although systemic and local Ang II and blood pressure were still elevated. Aldosterone supplementation reversed the beneficial effect of ADX. The present study indicates that aldosterone rather than Ang II plays a central and direct role in the pathogenesis of renal injury by L-NAME through inflammation, independent of its systemic hemodynamic effects.

Abstract 148: Superoxide Promotes Reversible Uncoupling Of Inducible Nitric Oxide Synthase, While Peroxynitrite Induces Irreversible And Complete Enzyme Inactivation

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jian Sun ◽  
Lawrence J Druhan ◽  
Jay L Zweier
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Inducible Nitric Oxide Synthase ◽  
Enzyme Inactivation ◽  
No Production ◽  
Dependent Manner ◽  
Inos Activity ◽  
Activity Loss ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

Inducible nitric oxide synthase (iNOS) is present in the post-ischemic heart, and plays an important role in the pathogenesis of injury and remodeling. Oxidants formed during reperfusion injury are known to alter NOS function. In this study we compare and contrast how two biologically relevant oxidants, peroxynitrite (ONOO − ) and superoxide (O 2 − ), alter iNOS function and define the mechanisms involved for each. Nitric oxide (NO) generation rate of purified iNOS was quantified by the methemoglobin formation, O 2 −. generation was measured using EPR spin-trapping, and the quaternary structure of iNOS by size-exclusion FPLC. Tetrahydrobiopterin (BH 4 )-replete iNOS (1 μM) was exposed to O 2 −. , and ONOO − in concentrations from 0.01 μM to 500μM and NO production was measured with and without addition of excess BH 4 . ONOO − (50μM) decreased NO production to 19% ± 0.17 and excess BH 4 only partially restored activity to 48% ± 3.4. O 2 −. (50 μM) reduced NO production to 42% ± 1.2 and the excess BH 4 completely restored activity to 100% ± 3.1. ONOO − exerted the highest decrease in NO production rate (96% ± 1.3 activity loss at 500 μM ONOO − ) and no activity was restored by excess BH 4 . In contrast, O 2 −. induced a significant decrease (90% ± 1.2 activity loss at 500 μM O 2 −. ), however excess BH 4 restored the iNOS activity back to 69% ± 5.6.O 2 −. exposure enhanced O 2 −. production from iNOS (up to 155% ± 0.72 at 50 μM O 2 −. ), while ONOO − at higher concentrations (>20μM) reduced O 2 −. production (10% ± 3.2 decrease at 50 μM ONOO − ). We also found that incubation with ONOO − and O 2 −. induced iNOS monomerization. In conclusion, both ONOO − and O 2 −. decrease iNOS NO production in a dose dependent manner. Adding excess BH 4 only partially restore the loss of NO production induced by ONOO − , but almost completely restore the loss of NO production induced by O 2 −.. Therefore, O 2 −. promotes the uncoupling of iNOS and elevates O 2 −. production by oxidizing the protein bound BH 4 with subsequent formation of NOS monomer in a reversible fashion. Conversely, ONOO − induces irreversible enzyme inactivation and decreases both NO and O 2 −. production. Although oxidation of BH 4 is involved in the observed ONOO − induced loss of iNOS activity, there are other causes, including oxidation of critical amino acid residues.

Nitric oxide synthase regulation during embryonic implantation

1997 ◽  
Vol 9 (5) ◽  
pp. 557 ◽  
Author(s):  
V. Novaro ◽  
E. González ◽  
A. Jawerbaum ◽  
V. Rettori ◽  
G. Canteros ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Receptor Antagonist ◽  
Early Pregnancy ◽  
Embryo Implantation ◽  
Competitive Inhibitor ◽  
No Production ◽  
Physiological Relevance ◽  
Synthase Regulation ◽  
Oxide Synthase

It has previously been demonstrated that uterine nitric oxide synthase (NOS) activity increases before embryonic implantation in rats. The aim of the present work was to investigate the regulation and the physiological relevance of the nitric oxide (NO) system in ovoimplantation. The increase in NOS activity in early pregnancy was found to be independent of the presence of embryos in the uterus. Whereas the Ca2+-dependent isoform of NOS increased gradually in the preimplantation days, the Ca2+-independent isoform increased just at the beginning of implantation (Day 5, 1800 hours); then the activity of both isoforms declined. Oestradiol, whose concentration peaks before implantation, might be regulating NOS activity in the uterus, since treatment of rats with tamoxifen, a receptor antagonist, reduces the activity of both isoforms to preimplantation levels. Intraluminal injections of L-NAME (0·5 mg kg-1), a competitive inhibitor of NOS, reduced by 50% the number of implanted embryos; this suggests that the NO system plays a role during implantation. The data suggest that oestradiol might be a modulator of NOS activity during nidation and that NO production is necessary to achieve a successful embryo implantation.

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