Short-term exposure to homocysteine depresses rat aortic contractility by an endothelium-dependent mechanism

2000 ◽  
Vol 78 (6) ◽  
pp. 500-506 ◽  
Author(s):  
S Wang ◽  
G Wright ◽  
J Harrah ◽  
R Touchon ◽  
W McCumbee ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Nitric Oxide Synthase ◽  
Contractile Response ◽  
Fold Increase ◽  
No Production ◽  
Short Term ◽  
Short Term Exposure ◽  
Oxide Synthase

The effect of short-term exposure to homocysteine (Hcy) on the contractile characteristics of rat aortic tissue was assessed both in vitro and in vivo. The contractile response of Hcy-treated aortic rings in culture for 1 or 4 days was unchanged from control responses. By comparison, aortic rings from animals injected with Hcy showed marked attenuation of response compared with controls injected with saline, cysteine or methionine. The contractile response to K+ was decreased within 24 hours of Hcy injection, whereas the response to both K+ (-27%) and noradrenaline (-56%) was significantly decreased by 4 days. In contrast, the contractile response to phorbol-12,13-dibutyrate was not different between Hcy and control groups. Intimal rubbing completely restored the responsiveness of Hcy-treated tissue to K+ and noradrenaline. By comparison, L-NAME only partially restored contractile responsiveness, while the cyclooxygenase inhibitor indomethacin had no effect on contractile attenuation induced by Hcy. Western blot analysis showed a 2-fold increase of endothelial nitric oxide synthase (eNOS) and a 3-fold increase in inducible nitric oxide synthase (iNOS) protein expression in the aortic endothelial cells from Hcy-injected rats. The results indicate an early detectable effect of Hcy on the in vivo contractile properties of vascular smooth muscle. The effect is endothelium-mediated and may vary depending on the agonist studied. The mechanism is uncertain but appears to involve increased nitric oxide (NO) production. Finally, the data suggest that attenuation of contraction may not be due to a direct effect of Hcy but that the compound is modified or acts indirectly in vivo.Key words: nitric oxide, nitric oxide synthase, in vivo, smooth muscle.

TNF-alpha and IFN-gamma induce expression of nitric oxide synthase in cultured rat medullary interstitial cells

1995 ◽  
Vol 269 (2) ◽  
pp. F212-F217 ◽  
Author(s):  
K. S. Lau ◽  
O. Nakashima ◽  
G. R. Aalund ◽  
L. Hogarth ◽  
K. Ujiie ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Nitric Oxide Synthase ◽  
Vascular Smooth Muscle ◽  
Guanylyl Cyclase ◽  
Soluble Guanylyl Cyclase ◽  
Tnf Alpha ◽  
No Production ◽  
Ifn Gamma ◽  
Oxide Synthase

Cytokines increase the expression of the inducible (type II) nitric oxide synthase (NOS) in macrophages, liver, and renal epithelial cells. Previously, we found that cultured rat medullary interstitial cells (RMIC) contain high levels of soluble guanylyl cyclase. To determine whether these cells can also produce NO, we studied the effects of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) on NO production, NOS II mRNA, and NOS II protein expression. Both TNF-alpha and IFN-gamma, in the presence of a low concentration of the other cytokine, caused dose-dependent increases in NO production. Exposure to TNF-alpha and IFN-gamma stimulated the production of NOS II mRNA, as determined by Northern blotting. Restriction mapping of reverse transcription-polymerase chain reaction products indicated that normal cells contained macrophage NOS II, whereas cytokine-stimulated cells contained primarily vascular smooth muscle NOS II and some macrophage NOS II. The appearance of NOS II protein was demonstrated by Western blotting. RMIC cell guanosine 3',5'-cyclic monophosphate accumulation increased 129-fold in response to the cytokines. NOS inhibitors decreased nitrite production. We conclude that 1) TNF-alpha and IFN-gamma induce the expression of vascular smooth muscle NOS II and production of NO in RMIC, and 2) NO acts as an autocrine activator of the soluble guanylyl cyclase in RMIC.

scholarly journals Nitric oxide regulates nitric oxide synthase-2 gene expression by inhibiting NF-κB binding to DNA

1997 ◽  
Vol 322 (2) ◽  
pp. 609-613 ◽  
Author(s):  
Song Kyu PARK ◽  
Hsin Lee LIN ◽  
Sean MURPHY
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Interferon Γ ◽  
No Production ◽  
No Donor ◽  
Nitric Oxide Synthase 2 ◽  
Oxide Synthase ◽  
Spermine Nonoate ◽  
Dna Complex

Treatment of astroglial cells with interleukin 1β and interferon γ transcriptionally activates the nitric oxide synthase (NOS)-2 gene. The duration of mRNA expression is brief because of transcript instability. In addition, NO donors reduce the expression of NOS-2 mRNA dramatically by reducing the rate of transcription. In this study we observed that the NO donor, spermine NONOate did not inhibit the activation and translocation of NF-κB, a key transcription factor in the induction of NOS-2, but inhibited formation of the NF-κB–DNA complex. This effect was reversed by methaemoglobin (acting as an NO trap) and by the reducing agent dithiothreitol. Formation of the interferon-regulatory factor–DNA complex was unaffected by NO. These results suggest that NO can modulate its own production by interfering with NF-κB interaction with the promoter region of the NOS gene, a negative feedback effect that may be important for limiting NO production in vivo.

In vivo treatment with endotoxin induces nitric oxide synthase in rat main pulmonary artery

1995 ◽  
Vol 268 (3) ◽  
pp. L509-L518 ◽  
Author(s):  
M. J. Griffiths ◽  
S. Liu ◽  
N. P. Curzen ◽  
M. Messent ◽  
T. W. Evans
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Contractile Response ◽  
Main Pulmonary Artery ◽  
Pulmonary Arteries ◽  
No Synthase ◽  
Oxide Synthase ◽  
Lps Treatment

Our aim was to demonstrate increased NO activity from inducible NO synthase (iNOS) in pulmonary arteries (PA) from rats treated with endotoxin [lipopolysaccharide (LPS), 20 mg/kg ip]. LPS treatment diminished the contractile response of PA to potassium chloride (KCl) and phenylephrine (PE) and increased levels of guanosine 3',5'-cyclic monophosphate (cGMP) in endothelium-denuded vessels. Both the NO synthase (NOS) antagonists NG-monomethyl-L-arginine (L-NMMA; nonselective) and aminoguanidine (selective for iNOS) enhanced PE-induced contraction in endothelium-denuded vessels from LPS-treated rats. Furthermore, L-NMMA-induced contraction of endothelium-denuded vessels from LPS-treated rats was stereospecifically antagonized by L-arginine and associated with decreased cGMP levels. These data suggest that NO is produced in increased amounts from PA smooth muscle after LPS treatment. LPS treatment caused increased expression of mRNA for iNOS in PA. This effect of LPS was attenuated by pretreatment with dexamethasone, suggesting that induction of NOS in PA smooth muscle underlies the increased NO activity associated with LPS administration.

Abstract 1333: Modulation Of Cardiac Beta-adrenergic Responsiveness By The Neuronal Nitric Oxide Synthase/Sarcolemmal Calcium Pump Complex

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Tamer M Mohamed ◽  
Delvac Oceandy ◽  
Nasser Alatwi ◽  
Florence Baudoin ◽  
Elizabeth J Cartwright ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Neuronal Nitric Oxide Synthase ◽  
Neonatal Rat ◽  
No Production ◽  
Adrenergic Stimulation ◽  
Rat Cardiomyocytes ◽  
Adrenergic Response ◽  
Oxide Synthase

The pivotal role of neuronal nitric oxide synthase (nNOS) in regulating cardiac function has only recently been unveiled. Notably, others have shown that responsiveness to β-adrenergic stimulation is dependent on nNOS activity. In a cellular model, we showed that the Ca 2+ /calmodulin-dependent nNOS activity is reduced by overexpression of isoform 4b of the plasma membrane Ca 2+ /Calmodulin-dependent Ca 2+ -pump (PMCA4b), which binds to nNOS. We demonstrated that PMCA4b overexpression in the heart reduced β-adrenergic responsiveness in vivo via an nNOS dependent mechanism (Oceandy et al, Circulation 2007). Here we investigated the cellular mechanisms of the regulation of the β-adrenergic response by PMCA4b. We used an adenoviral system to overexpress PMCA4b (PMCA4b cells) or LacZ (control, C) in neonatal rat cardiomyocytes. PMCA4b cells showed an 18±5% and 24±5% reduction in nitric oxide (DAF-FM fluorescence) and cGMP levels, respectively (n=6, p<0.05 each) compared to C demonstrating the regulation of NO production by the PMCA4b in this system. Since nNOS has been shown to regulate phospholamban (PLB) phosphorylation, we examined phosphorylation of PLB at Ser16. PMCA4b cells showed a significant increase in Ser16-PLB at baseline (66±17%, p<0.05) compared to C. As a result of increased baseline Ser16-PLB in PMCA4b cells, β-adrenergic stimulation of PMCA4b cells using 2μM isoproter-enol (IP) showed reduced relative induction in Ser16-PLB (23±10% vs. 78±19% in C; n=5, p<0.05). Further analysis in adult cardiomyocytes isolated from our PMCA4b transgenic mice (PMCA4b TG) demonstrated that PMCA4b TG showed 3-fold higher Ser16-PLB phosphorylation at baseline compared to wild type (WT) myocytes and the relative response following β-adrenergic stimulation was significantly reduced (1.2±0.2 fold induction after IP treatment in PMCA4b TG, vs. 3.1±0.7 in WT, n=5, p<0.05). Thus, PMCA4b regulates NO production from nNOS, which in turn modulates cGMP levels and PLB phosphorylation. These findings provide mechanistic insight into the regulation of the β-adrenergic response in the heart by PMCA4b and place this Ca 2+ -pump upstream of the recently described pathway linking nNOS and Ser16-PLB phosphorylation and downstream of the β-adrenergic receptor(s).

Evaluation of islet heme oxygenase-CO and nitric oxide synthase-NO pathways during acute endotoxemia

2001 ◽  
Vol 280 (5) ◽  
pp. C1242-C1254 ◽  
Author(s):  
Ragnar Henningsson ◽  
Per Alm ◽  
Ingmar Lundquist
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Heme Oxygenase ◽  
Insulin Response ◽  
Glucagon Secretion ◽  
No Production ◽  
Compensatory Mechanisms ◽  
Oxide Synthase

We investigated, by a combined in vivo and in vitro approach, the temporal changes of islet nitric oxide synthase (NOS)-derived nitric oxide (NO) and heme oxygenase (HO)-derived carbon monoxide (CO) production in relation to insulin and glucagon secretion during acute endotoxemia induced by lipopolysaccharide (LPS) in mice. Basal plasma glucagon, islet cAMP and cGMP content after in vitro incubation, the insulin response to glucose in vivo and in vitro, and the insulin and glucagon responses to the adenylate cyclase activator forskolin were greatly increased after LPS. Immunoblots demonstrated expression of inducible NOS (iNOS), inducible HO (HO-1), and an increased expression of constitutive HO (HO-2) in islet tissue. Immunocytochemistry revealed a marked expression of iNOS in many β-cells, but only in single α-cells after LPS. Moreover, biochemical analysis showed a time dependent and markedly increased production of NO and CO in these islets. Addition of a NOS inhibitor to such islets evoked a marked potentiation of glucose-stimulated insulin release. Finally, after incubation in vitro, a marked suppression of NO production by both exogenous CO and glucagon was observed in control islets. This effect occurred independently of a concomitant inhibition of guanylyl cyclase. We suggest that the impairing effect of increased production of islet NO on insulin secretion during acute endotoxemia is antagonized by increased activities of the islet cAMP and HO-CO systems, constituting important compensatory mechanisms against the noxious and diabetogenic actions of NO in endocrine pancreas.

In vivo pharmacological evaluation off two novel type II (inducible) nitric oxide synthase inhibitors

1995 ◽  
Vol 73 (5) ◽  
pp. 665-669 ◽  
Author(s):  
W. Ross Tracey ◽  
Masaki Nakane ◽  
Fatima Basha ◽  
George Carter
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Inducible Nitric Oxide Synthase ◽  
No Production ◽  
Type Ii ◽  
Nos Inhibitors ◽  
Oxide Synthase ◽  
Dose Dependent ◽  
Inducible Nitric Oxide

Selective type II (inducible) nitric oxide synthase (NOS) inhibitors have several potential therapeutic applications, including treatment of sepsis, diabetes, and autoimmune diseases. The ability of two novel, selective inhibitors of type II NOS, S-ethylisothiourea (EIT) and 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), to inhibit type II NOS function in vivo was studied in lipopolysaccharide (LPS) treated rats. Type II NOS activity was assessed by measuring changes in plasma nitrite and nitrate concentrations ([NOx]). Both EIT and AMT elicited a dose-dependent and >95% inhibition of the LPS-induced increase in plasma [NOx]. The ED50 values for EIT and AMT were 0.4 and 0.2 mg/kg, respectively. In addition, the administration of LPS and either NOS inhibitor resulted in a dose-dependent increase in animal mortality; neither compound was lethal when administered alone. Pretreatment with L-arginine (but not D-arginine) prevented the mortality, while not affecting the type II NOS-dependent NO production, suggesting the toxicity may be due to inhibition of one of the other NOS isoforms (endothelial or neuronal). Thus, although EIT and AMT are potent inhibitors of type II NOS function in vivo, type II NOS inhibitors of even greater selectivity may need to be developed for therapeutic applications.Key words: nitric oxide, nitrite, nitrate, sepsis, lipopolysaccharide.

The role of nitric oxide synthase/nitric oxide in vascular smooth muscle control

Perfusion ◽  
2000 ◽  
Vol 15 (2) ◽  
pp. 97-104 ◽  
Author(s):  
D Bradford Sanders ◽  
Tara Kelley ◽  
Douglas Larson
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Nitric Oxide Synthase ◽  
Vascular Smooth Muscle ◽  
Vascular Function ◽  
No Production ◽  
Amyl Nitrite ◽  
Vascular Compliance ◽  
Oxide Synthase

Vascular compliance is dependent on endogenous and exogenous sources of nitric oxide (NO). In a discussion of therapeutics and NO derived via nitric oxide synthase (NOS) enzymes, it is necessary to examine the pathways of each drug to provide the clinical perfusionist with a greater understanding of the role of NOS/NO in vascular function. Endothelial-derived NO is a contributor in the vasoregulation of vascular smooth muscle. Therapeutics seek to mimic the vasodilatory effects of the endogenous NO. The therapeutics included in this review are nitroglycerin, nitroprusside, amyl nitrite, and inhalation of NO. L-Arginine supplementation provides additional substrate for the endogenous pathway that can augment NO production. NO is a small bioactive molecule involved in various biochemical pathways. Dysregulation of NO production can impair normal physiologic control of vascular compliance. Therefore, the purpose of this review is to provide the perfusionist with an understanding of the biochemical and pharmacological aspects of NOS/NO associated with vascular function.

scholarly journals Identification of Golgi-localized acyl transferases that palmitoylate and regulate endothelial nitric oxide synthase

2006 ◽  
Vol 174 (3) ◽  
pp. 369-377 ◽  
Author(s):  
Carlos Fernández-Hernando ◽  
Masaki Fukata ◽  
Pascal N. Bernatchez ◽  
Yuko Fukata ◽  
Michelle I. Lin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Cdna Clones ◽  
No Production ◽  
Human Endothelial Cells ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

Lipid modifications mediate the subcellular localization and biological activity of many proteins, including endothelial nitric oxide synthase (eNOS). This enzyme resides on the cytoplasmic aspect of the Golgi apparatus and in caveolae and is dually acylated by both N-myristoylation and S-palmitoylation. Palmitoylation-deficient mutants of eNOS release less nitric oxide (NO). We identify enzymes that palmitoylate eNOS in vivo. Transfection of human embryonic kidney 293 cells with the complementary DNA (cDNA) for eNOS and 23 cDNA clones encoding the Asp-His-His-Cys motif (DHHC) palmitoyl transferase family members showed that five clones (2, 3, 7, 8, and 21) enhanced incorporation of [3H]-palmitate into eNOS. Human endothelial cells express all five of these enzymes, which colocalize with eNOS in the Golgi and plasma membrane and interact with eNOS. Importantly, inhibition of DHHC-21 palmitoyl transferase, but not DHHC-3, in human endothelial cells reduces eNOS palmitoylation, eNOS targeting, and stimulated NO production. Collectively, our data describe five new Golgi-targeted DHHC enzymes in human endothelial cells and suggest a regulatory role of DHHC-21 in governing eNOS localization and function.

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