Nitric oxide (Vascular biology)

Three dimensional (3D) nano-structured crystals have received extensive attention for their superior properties over zero dimensional (0D), one dimensional (1D), or two dimensional (2D) nanomaterials in many areas. This review is generalized for the group of chalcogenide nanoflowers (NFs) by the synthetic techniques, such as solvothermal, wet chemical, sol-gel, surface oxidation, microwave, coating, electrochemical, and several other methods. The formation mechanism was also described for the purpose of opening up new food for thoughts to bring up new functionality of materials by tuning the morphology of crystals. The pH value or the template plays fundamental role in forming the nano-flowered structure. Moreover, the correlations between the surface area (SA), contact angle (CA), and the NFs are also discussed within the context. Here, we also discussed some patents relevant to the topic.

Voor mijn ouders, mijn broertje, Mayke, en niet te vergeten alle ratten die onvrijwillig hun leven ter beschikking hebben gesteld voor deze studies In the time of your life, live -so that in good time there shall be no ugliness or death for yourself or for any life your life touches.

BACKGROUND AND PURPOSE:

Benznidazole (Bz) is the therapy currently available for clinical treatment of Chagas' disease. However, many strains of Trypanosoma cruzi parasites are naturally resistant. Nitric oxide (NO) produced by activated macrophages is crucial to the intracellular killing of parasites. Here, we investigate the in vitro and in vivo activities against T. cruzi, of the NO donor, trans-[RuCl([15]aneN(4))NO](2+).
EXPERIMENTAL APPROACH:

Trans-[RuCl([15]aneN(4))NO](2+)was incubated with a partially drug-resistant T. cruzi Y strain and the anti-proliferative (epimastigote form) and trypanocidal activities (trypomastigote and amastigote) evaluated. Mice were treated during the acute phase of Chagas' disease. The anti-T. cruzi activity was evaluated by parasitaemia, survival rate, cardiac parasitism, myocarditis and the curative rate.
KEY RESULTS:

Trans-[RuCl([15]aneN(4))NO](2+) was 10- and 100-fold more active than Bz against amastigotes and trypomastigotes respectively. Further, trans-[RuCl([15]aneN(4))NO](2+) (0.1 mM) induced 100% of trypanocidal activity (trypomastigotes forms) in vitro. Trans-[RuCl([15]aneN(4))NO](2+) induced permanent suppression of parasitaemia and 100% survival in a murine model of acute Chagas' disease. When the drugs were given alone, parasitological cures were confirmed in only 30 and 40% of the animals treated with the NO donor (3.33 micromol.kg(-1).day(-1)) and Bz (385 micromol.kg(-1).day(-1)), respectively, but when given together, 80% of the animals were parasitologically cured. The cured animals showed an absence of myocarditis and a normalisation of cytokine production in the sera. In addition, no in vitro toxicity was observed at the tested doses.
CONCLUSIONS AND IMPLICATIONS:

These findings indicate that trans-[RuCl([15]aneN(4))NO](2+)is a promising lead compound for the treatment of human Chagas' disease.

Voor mijn ouders, mijn broertje, Mayke, en niet te vergeten alle ratten die onvrijwillig hun leven ter beschikking hebben gesteld voor deze studies In the time of your life, live -so that in good time there shall be no ugliness or death for yourself or for any life your life touches.

Heme oygenase-1 (HO-1) is an inducible stress protein the expression of which can be markedly augmented in eukaryotes by a wide range of substances that cause a transient change in the cellular redox state. The importance of this protein in physiology and disease is underlined by the versatility of HO-1 inducers and the functional role attributed to HO-1 products (carbon monoxide and bilirubin) in conditions that are associated with moderate or severe cellular stress. An intriguing aspect is the recent evidence showing that nitric oxide (NO), a ubiquitous signaling molecule, finely modulates the activation of HO-1 expression. Since the effects of oxidative stress on the regulation of the HO-1 gene have been well established and characterized, this review will focus on the biological relevance of redox signals involving NO and reactive nitrogen species that lead to up-regulation of the HO-1 pathway, with particular emphasis to vascular tissues and the cardiovascular system.

Background/Purpose
GP.Mur is a clinically important red blood cell (RBC) type. GP.Mur and band 3 interact on the RBCs. We previously observed that healthy adults with GP.Mur type present slightly higher blood pressure (BP). Because band 3 and Hb comodulate nitric oxide (NO)-dependent vasodilation and hemoglobin (Hb) is positively associated with BP, we aimed to test whether these could contribute to higher BP in GP.Mur+ people.

Methods
We recruited 989 non-elderly adults (21% GP.Mur) free of catastrophic illness and not on cardiovascular or anti-hypertensive medication. Their body indices, blood lab data and lifestyle data were collected for analyses of potential BP-related factors (BMI, age, smoking, Hb, and GP.Mur).

Results
BMI and age remained the most significant contributors to BP. GP.Mur slightly increased systolic BP (SBP). The direct correlation between Hb and BP was only found in Taiwanese non-anemic men, not women. After age and BMI adjusted, we estimated an increase of 1.8 mmHg and 2.6 mmHg of SBP by 1 g/dL Hb among men without and with GP.Mur type, respectively. Hb was generally lower among people expressing GP.Mur, which likely limited their larger impact on BP.

Conclusion
GP.Mur contributed to BP in both Hb-dependent and Hb-independent fashion. A pronounced impact of hemoglobin on BP likely requires sufficient Hb, as GP.Mur increased the sensitivity of SBP to Hb only in non-anemic Taiwanese men, and not in Taiwanese women or anemic men. The mechanism through which GP.Mur affected BP independent of Hb is unknown.

Transcriptional changes of the enzyme nitric oxide synthase I (NOS1) are believed to play a role in the development of many diseases. The gene for NOS1 has 12 alternative first exons (1A-1L). The 1F exon is one of the most highly utilized first exons in the brain and has a polymorphism ((TG) m TA(TG) n ) located in its promoter region. The polymorphism's length has been suggested to affect NOS1 transcription and play a role in Parkinson's disease (PD); however, the actual influence of the polymorphism on NOS1 transcription has not been studied. To better characterize the links of the polymorphism with PD, a genotyping study was done comparing polymorphism length among 170 PD patients and 150 age-matched controls. The pattern of changes between the two group's allele frequencies shows statistical significance (P 5 0.0359). The smallest polymorphism sizes are more predominant among PD patients than controls. To study the effects of this polymorphism on NOS1 gene transcription, reporter gene constructs were made by cloning the NOS1 1F promoter with polymorphism lengths of either 42, 54, or 62 bp in front of the luciferase gene and transfecting them into HeLa or Sk-N-MC cells. NOS1-directed reporter gene constructs with the 62-bp polymorphism increased transcription of luciferase 2.2-fold in HeLa and 1.8-fold in Sk-N-MC cells compared with reporter gene constructs with the 42-bp polymorphism. These data suggest that if smaller polymorphism size contributes to the higher NOS1 levels in PD patients, an as yet unknown transcriptional mechanism is required. V V C 2009 Wiley-Liss, Inc.

GP.Mur, a red blood cell (RBC) hybrid protein encoded by glycophorin B-A-B, increases expression of erythroid band 3 (Anion Exchanger-1, SLC4A1). GP.Mur is extremely rare but has a prevalence of 1–10% in regions of Southeast Asia. We unexpectedly found slightly higher blood pressure (BP) among healthy Taiwanese adults with GP.Mur. Since band 3 has been suggested to interact with hemoglobin (Hb) to modulate nitric oxide (NO)-dependent hypoxic vasodilation during the respiratory cycle, we hypothesized that GP.Mur red cells could exert differentiable effects on vascular tone. Here we recruited GP.Mur-positive and GP.Mur-negative elite male college athletes, as well as age-matched, GP.Mur-negative non-athletes, for NO-dependent flow-mediated dilation (FMD) and NO-independent dilation (NID). The subjects were also tested for plasma nitrite and nitrate before and after arterial occlusion in FMD. GP.Mur+ and non-GP.Mur athletes exhibited similar heart rates and blood pressure, but GP.Mur+ ...

Journal of Cardiovascular Pharmacology:
November 2006 - Volume 48 - Issue 5 - pp 191-198


Ajayi, Adesuyi A Leslie MD, PhD*,†; Fidelis, Paul DVM*


Background: There is increasing evidence that endogenous sex hormones regulate vascular reactivity, and testosterone may contribute to the worse prognosis for renal disease in men. Male Zucker diabetic rats exhibit improved renal hemodynamic responses after castration. It is, however, unclear whether endogenous testosterone affects renal and systemic microcirculatory responses in the female sex, especially in type 2 diabetes.
Aim: To test the hypothesis that endogenous testosterone in the female Zucker diabetic rat exerts a pathophysiologically relevant modulation of endothelial and renal microvascular function.
Methods: Female Zucker diabetic rats (FZDR) aged 5−6 weeks and from the same litter were divided into 2 groups (n = 6−8 each). The experimental group received the androgen receptor blocker flutamide, dissolved in alcohol and added to their drinking water (500 mL) at 20 mg/rat/week. The control FZDR received only the alcohol vehicle added to the same volume of drinking water. Both FZDR groups were treated for 3 months before undergoing the hemodynamic studies. A sex comparison control group of male Zucker diabetic rats (MZDR), also aged 5−6 weeks, was studied, following same protocol. Mean arterial pressure (MAP) and renal cortical blood flow (RCF) response to phenylephrine, acetylcholine, TXA2−mimetic U46619, endothelin-1 (ET-1), angiotensin II, and l-NG-nitro arginine methyl ester were studied. Furthermore, the role of protein kinase C in the responses was assessed using phorbol-12,13 dibutyrate 10−4 M. The impact of flutamide on body weights and blood glucose of the rats were also determined.
Results: Flutamide-treated FZDR had a significant reduction in body weight/adiposity to 432 ± 44 g, compared to controls at 553 ± 37 g (P = 0.045), and random blood glucose concentration of 185 ± 44 g/dL, compared to the control FZDR at 475 ± 34 g/dL (P = 0.002). Vehicle-treated FZDR (n = 6−8), exhibited little or no systemic or renal response to any of the agonists. By contrast, flutamide treatment of FZDR (n = 5−7) caused a normalization of the dose-dependent MAP and RCF pressor response to phenylephrine [P < 0.005, analysis of variance (ANOVA)] and the vasodilator response to acetylcholine (P <. 0.01, ANOVA). Flutamide-treated FZDR showed enhanced pressor response to U46619 (P = 0.024, ANOVA), ET-1, and angiotensin II (P < 0.03, ANOVA). Surprisingly, the augmented systemic pressor action of U46619 and ET-1 was accompanied by a renal vasodilator action, with paradoxic RCF increases to U46619 (P < 0.003, ANOVA) and to ET-1 (P < 0.001, ANOVA) only in flutamide-treated FZDR. By contrast, flutamide-treated MZDR exhibited no significant change in body weight and an attenuation of the vasoconstrictor responses and enhanced nitric oxide-mediated dilatation compared with male controls. However, no specific effect on ET-1 or TXA2 receptor-mediated renal perfusion was discernible. Both l-NG-nitro arginine methyl ester and the protein kinase C agonist phorbol-12,13 dibutyrate [10−4 M] significantly increased MAP and reduced RCF (P < 0.03) in the experimental FZDR compared with their controls.
Conclusion: Flutamide administration to FZDR resulted in the reversal of abnormal systemic and renal α-1-mediated vasoconstriction and enhanced nitric oxide-mediated vasodilation. Flutamide caused a paradoxic but specific increase in renal perfusion during ET-1 and TXA2 receptor activation, which could be renoprotective in females. The salutary effects of flutamide on vascular reactivity in the FZDR may be mediated by a protein kinase C-dependent mechanism. These results are compatible with the notion that endogenous testosterone may regulate systemic and renal microcirculation in the female sex and in the type 2 diabetic state.

GP.Mur, commonly known as Miltenberger subtype III, is a clinically-important red blood cell (RBC) phenotype unique among Southeast Asians (SEA). On the GP.Mur+ erythrocyte membrane, glycophorin B-A-B hybrid protein is expressed, instead of glycophorin B (GPB). Different from GPB that does not have any known function, GP.Mur hybrid protein promotes expression of anion exchanger-1 (AE1) on the RBC membrane and support AE1-relevant physiological functions in GP.Mur+ carriers. In our previous human studies, we unexpectedly uncovered that GP.Mur+ carriers have slightly higher blood pressure (BP) than GP.Mur-negative people. Since AE1 has been implicated a role in modulation of NO bioavailability and hemoglobin (Hb) is a major NO scavenger, we hypothesized that the slightly but significantly higher BP in GP.Mur carriers might be related to Hb-mediated NO processing.

Methods
With the approval of hospital Institutional Review Board, healthy, non-smoker subjects aged between 20 and 55 were recruited at Taitung MacKay Memorial Hospital (TT-MMH). Besides general physical assessment, recruited subjects were tested for CBC and RBC phenotypes, including GP.Mur.

Results
345 male and 515 female non-smoker adults were recruited from Taitung County, Taiwan, and 22.1% of them bear GP.Mur blood type. For male and female cohorts, GP.Mur erythrocyte expression was significantly associated with slightly higher systolic BP (SBP) (122.2±12.9 mmHg [non-GP.Mur male] versus 127.8±14.4 mmHg [GP.Mur male]; 115.0±13.0 mmHg [non-GP.Mur female] versus 118.0±13.4 mmHg [GP.Mur female]). Hb levels were not affected by GP.Mur. Hb is known to be positively associated with SBP. We indeed found a Pearson correlation of 0.164 between Hb (g/dL) and SBP (mmHg) in non-GP.Mur male subjects (*p~0.007). However, Hb-SBP associations were not observed in our female cohorts with or without GP.Mur. Intriguingly, the Pearson correlation between Hb and SBP from the GP.Mur male group was doubled, compared to that from the GP.Mur-negative male group (Pearson correlation: 0.299 [GP.Mur male] versus 0.164 [non-GP.Mur male]).

Conclusion
From the differences in Hb-SBP correlations in male, the effects of NO-scavenging by Hb were likely more substantial in the presence of GP.Mur and/or higher AE1 expression. We did not observe any positive associations in our SEA female subjects, presumably due to menstrual cycle and that SEA women were generally more anemic.

The paper summarizes the results of studies of the role played by the plant leaf extracellular space in the regulation of mesophyll
cells water exchange, photosynthesis and export of assimilates to consuming sink organs. When comparing different methods of
assessing water exchange rates, the participation of the plasmalemma in the formation of the leaf water potential was shown. Using
the in vivo method of extracting the contents of the apoplast, the dynamics of the exit and movement of labeled photosynthetic
products through the extracellular space was traced. It was shown that there is a circulation of assimilates in the plant. As the
sugars move downwards along the phloem, they partially escape into the extracellular space and are carried away upwards by the
transpiration stream, where they re-enter the leaves that have completed growth and are re-exported. This creates a common pool
of photosynthetic products, which serves as a test of the balance between photosynthesis and the use of assimilates by consuming
organs. Analysis of the metabolism of 14C-labelled photosynthetic products in genetically transformed plants with increased or
decreased apo plastic invertase activity showed the key importance of this enzyme in the regulation of photosynthesis and export of
14CO2
assimilation products from the leaf. Simultaneous measurement of photosynthesis and transpiration in leaves of these plants
under rapid changes in light exposure showed a regulatory link of photo processes in chloroplasts, dark reactions of carbon dioxide
assimilation by mesophyll cells and transport of assimilates into phloem, the actuator of which is the leaf stomata. If the balance
between photo-processes and the reduction of CO2
to sugars in the cell is disturbed, the ratio of sugars to organic acid changes, which
leads to a pH shift in mesophyll cells, and then in the apoplast, which alters apo plastic invertase activity. Accordingly, depending on
the degree of sucrose hydrolysis in the apoplast, the osmolarity of the extracellular medium changes (1 mole of sucrose → 2 moles
of hexoses), increasing with approaching to the stomatal aperture, which affects the stomata and leaf resistance to CO2
diffusion. As
a result, the ratio between light and dark processes is normalized.

Background and purpose:  Benznidazole (Bz) is the therapy currently available for clinical treatment of Chagas' disease. However, many strains of Trypanosoma cruzi parasites are naturally resistant. Nitric oxide (NO) produced by activated macrophages is crucial to the intracellular killing of parasites. Here, we investigate the in vitro and in vivo activities against T. cruzi, of the NO donor, trans-[RuCl([15]aneN4)NO]2+.Experimental approach: Trans-[RuCl([15]aneN4)NO]2+was incubated with a partially drug-resistant T. cruzi Y strain and the anti-proliferative (epimastigote form) and trypanocidal activities (trypomastigote and amastigote) evaluated. Mice were treated during the acute phase of Chagas' disease. The anti-T. cruzi activity was evaluated by parasitaemia, survival rate, cardiac parasitism, myocarditis and the curative rate.Key results: Trans-[RuCl([15]aneN4)NO]2+ was 10- and 100-fold more active than Bz against amastigotes and trypomastigotes respectively. Further, trans-[RuCl([15]aneN4)NO]2+ (0.1 mM) induced 100% of trypanocidal activity (trypomastigotes forms) in vitro. Trans-[RuCl([15]aneN4)NO]2+ induced permanent suppression of parasitaemia and 100% survival in a murine model of acute Chagas' disease. When the drugs were given alone, parasitological cures were confirmed in only 30 and 40% of the animals treated with the NO donor (3.33 µmol·kg−1·day−1) and Bz (385 µmol·kg−1·day−1), respectively, but when given together, 80% of the animals were parasitologically cured. The cured animals showed an absence of myocarditis and a normalisation of cytokine production in the sera. In addition, no in vitro toxicity was observed at the tested doses.Conclusions and implications:  These findings indicate that trans-[RuCl([15]aneN4)NO]2+is a promising lead compound for the treatment of human Chagas' disease.This article is commented on by Machado et al., pp. 258–259 of this issue. To view this commentary visit http://dx.doi.org/10.1111/j.1476-5381.2010.00662.x and to view a related paper in this issue by Silva et al. visit http://dx.doi.org/10.1111/j.1476-5381.2010.00524.x

Human CO 2 respiration requires rapid conversion between CO 2 and HCO 3 2. Carbonic anhydrase II facilitates this reversible reaction inside red blood cells, and band 3 [anion exchanger 1 (AE1)] provides a passage for HCO 3 2 flux across the cell membrane. These 2 proteins are core components of the CO 2 transport metabolon. Intracellular H 2 O is necessary for CO 2 /HCO 3 2 conversion. However, abundantly expressed aquaporin 1 (AQP1) in erythrocytes is thought not to be part of band 3 complexes or the CO 2 transport metabolon. To solve this conundrum, we used Förster resonance energy transfer (FRET) measured by fluorescence lifetime imaging (FLIM-FRET) and identified interaction between aquaporin-1 and band 3 at a distance of 8 nm, within the range of dipole-dipole interaction. Notably, their interaction was adaptable to membrane tonicity changes. This suggests that the function of AQP1 in tonicity response could be coupled or correlated to its function in band 3-mediated CO 2 /HCO 3 2 exchange. By demonstrating AQP1 as a mobile component of the CO 2 transport metabolon, our results uncover a potential role of water channel in blood CO 2 transport and respiration.

Background and purpose: Benznidazole (Bz) is the therapy currently available for clinical treatment of Chagas' disease. However, many strains of Trypanosoma cruzi parasites are naturally resistant. Nitric oxide (NO) produced by activated macrophages is crucial to the intracellular killing of parasites. Here, we investigate the in vitro and in vivo activities against T. cruzi, of the NO donor, trans-[RuCl([15]aneN4)NO] 2+ . Experimental approach: Trans-[RuCl([15]aneN4)NO] 2+ was incubated with a partially drug-resistant T. cruzi Y strain and the anti-proliferative (epimastigote form) and trypanocidal activities (trypomastigote and amastigote) evaluated. Mice were treated during the acute phase of Chagas' disease. The anti-T. cruzi activity was evaluated by parasitaemia, survival rate, cardiac parasitism, myocarditis and the curative rate. Key results: Trans-[RuCl([15]aneN4)NO] 2+ was 10-and 100-fold more active than Bz against amastigotes and trypomastigotes respectively. Further, trans-[RuCl([15]aneN4)NO] 2+ (0.1 mM) induced 100% of trypanocidal activity (trypomastigotes forms) in vitro. Trans-[RuCl ([15]aneN4)NO] 2+ induced permanent suppression of parasitaemia and 100% survival in a murine model of acute Chagas' disease. When the drugs were given alone, parasitological cures were confirmed in only 30 and 40% of the animals treated with the NO donor (3.33 mmol·kg -1 ·day -1 ) and Bz (385 mmol·kg -1 ·day -1 ), respectively, but when given together, 80% of the animals were parasitologically cured. The cured animals showed an absence of myocarditis and a normalisation of cytokine production in the sera. In addition, no in vitro toxicity was observed at the tested doses. Conclusions and implications: These findings indicate that trans-[RuCl ([15]aneN4)NO] 2+ is a promising lead compound for the treatment of human Chagas' disease.

The effects of bradykinin and ATP on L-arginine transport and nitric oxide (NO) production were studied in porcine aortic endothelial cells cultured and perfused on microcarriers and deprived of L-arginine for 24 h. Stimulation of cells with bradykinin (100 nM) or ATP (100 ~tM) resulted in a rapid increase in L-arginine uptake and NO release. In the presence of nitro-L-arginine (100 gM), an inhibitor of NO synthase, the stimulatory effect of bradykinin on L-arginine uptake was partially inhibited while NO release was completely abolished. Nitro-L-arginine alone was not an inhibitor of basal L-arginine transport, suggesting that its inhibitory action was not directly on the L-arginine transporter but a result of the inhibition of NO generation. These data indicate that during agoniststimulated NO production there is a concomitant increase in the transport of L-arginine into endothelial cells providing a mechanism for the continual generation of NO. ~ ~99~ Academic Press, Inc. Nitric oxide synthesized from L-arginine by vascular endothelial cells accounts for the biological activity of endothelium derived relaxing factor (1,2). L-arginine infusion does not normally evoke hypotension in vivo, and isolated vascular preparations with intact endothelium relax little upon application of L-arginine (3-7). Similarly, the release of nitric oxide from endothelial cells cultured under normal conditions of arginine supply is not increased consistently by exogenous L-arginine (1). In contrast, L-arginine infusion causes hypotension under some surgical conditions (8) and acetylcholine-induced hypotension is potentiated by co-administration of L-arginine and reduced when plasma levels of arginine have been depleted (9,10). Likewise both basal and stimulated NO release from endothelial cells deprived of arginine are stimulated by application or co-administration of BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS arginine (1,11). These studies suggest that supply of extracellular L-arginine may be important for NO generation under certain conditions, such as L-arginine deprivation, where the usually high intracellular concentrations of arginine (0.4-0.8 mM) are significantly reduced (12,13) or during agonist-induced NO release where there is an increase in the metabolism of L-arginine to NO.

""NO potently up-regulates vascular haem oxygenase-1 (HO-1), an inducible defensive protein that degrades haem to CO, iron and the antioxidant bilirubin. Since several pathological states are characterized by increased NO production and liberation of haem from haem-containing proteins, we examined how NO influences HO-1 induction mediated by haemin. Aortic endothelial cells treated with S-nitroso-N-acetylpenicillamine (SNAP), sodium nitroprusside (SNP) or diethylenetriamine-NONOate (DETA/NO) and haemin exhibited higher levels of haem oxygenase activity compared with cells exposed to NO donors or haemin alone. This was accompanied by a marked increase in bilirubin production and, notably, by a strong magnification of cellular haem uptake. A role for haem metabolites in modulating HO-1 expression by NO was assessed by exposing cells to SNAP, SNP or DETA/NO in medium derived from cells treated with haemin,which contained increased bilirubin levels. This treatment considerably potentiated HO-1
expression and haem oxygenase activity mediated by NO and the use of a haem oxygenase inhibitor abolished this effect. Both iron liberated during haem breakdown and the formation of nitroxyl anion from NO appeared to partially contribute to the amplifying phenomenon; in addition, medium from haemintreated cells significantly augmented the release of NO by NO donors. Thus we have identified novel mechanisms related to the induction of HO-1 by NO indicating that the signalling actions of NO vary significantly in the presence of haem and haem
metabolites, ultimately increasing the defensive abilities of the endothelium to counteract oxidative and nitrosative stress.""

Toxic heavy metals such as cadmium (Cd) and copper (Cu) are global problems that are a growing threat to the environment. Despite some heavy metals are required for plant growth and development, others are considered toxic elements and do not play any known physiological role in plant cells. Elevated doses of Cd or Cu cause toxicity in plants and generate damages due to the stress condition and eventually cause a significant reduction in quantity and quality of crop plants. The nitric oxide (NO) donor sodium nitroprusside (SNP) is reported to alleviate the toxicity of some heavy metals like Cd and Cu. In the current study, the role of NO in alleviating stresses of Cd and Cu was investigated in in vitro-grown tobacco (Nicotiana tabacum) Based on plant growth, total chlorophyll contents, contents and activities of rubisco and rubisco activase. According to the results of this study, the growth and total chlorophyll contents of Cd/Cu stressed plants were hugely decreased in the absence of SNP, while the supplementation of SNP resulted in a significant increase of both fresh weight and total chlorophyll contents. Remarkable reductions of Rubisco and rubisco activase contents and activities were observed in Cd and Cu-induced plants. SNP supplemen-tation showed the highest contents and activities of rubisco and rubisco activase compared to the control and Cu/Cd-stressed plants. Taken together, our findings suggest that SNP could play a protective role in regulation of plant responses to abiotic stresses such as Cd and Cu by enhancing Rubisco and Rubisco activase.

Non-technical summary During hypoxia, there is less oxygen in the air we breathe and also in the blood being pumped away from the heart. Our blood vessels must relax in order to deliver more blood to match the resting oxygen demand of the muscles. The way in which multiple systems in the body coordinate this response is not well known. We examined the local response of the blood vessels to a hypoxic stimulus and show that two substances that the body produces, nitric oxide and prostaglandins, are necessary to cause relaxation of the blood vessels and increases in blood flow. These results help us better understand how oxygen delivery is regulated and may be especially important for populations that are unable to produce these substances that help increase blood flow, such as people with sleep apnoea, heart failure and diabetes.

This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO−) released upon the decomposition of Angeli's salt.Our results show that copper ions (from CuSO4) catalyze the rapid and efficient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1–100 μM) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from S-nitroso-N-acetyl-D,L-penicillamine (SNAP).Experiments with ascorbate (1 mM), which reduces Cu2+ ions to Cu+, and with the Cu2+ chelators, EDTA and cuprizone, and the Cu+ chelator, neocuproine, each at 1 mM, suggest that the oxidation is catalyzed by copper ions in both valency states.Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less efficient than CuSO4 in catalyzing the formation of nitric oxide from nitroxyl, while FeSO4, FeCl3, MnCl2, and ZnSO4 were inactive.Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30 u ml−1, respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10 u ml−1) and tyrosinase (250 u ml−1) were inactive.Our findings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive.This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO−) released upon the decomposition of Angeli's salt.Our results show that copper ions (from CuSO4) catalyze the rapid and efficient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1–100 μM) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from S-nitroso-N-acetyl-D,L-penicillamine (SNAP).Experiments with ascorbate (1 mM), which reduces Cu2+ ions to Cu+, and with the Cu2+ chelators, EDTA and cuprizone, and the Cu+ chelator, neocuproine, each at 1 mM, suggest that the oxidation is catalyzed by copper ions in both valency states.Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less efficient than CuSO4 in catalyzing the formation of nitric oxide from nitroxyl, while FeSO4, FeCl3, MnCl2, and ZnSO4 were inactive.Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30 u ml−1, respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10 u ml−1) and tyrosinase (250 u ml−1) were inactive.Our findings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive.British Journal of Pharmacology (2000) 131, 356–362; doi:10.1038/sj.bjp.0703550

Nitric oxide and S-nitrosothiols modulate a variety of important physiological activities. In vascular cells, agents that release NO and donate nitrosonium cation (NO-), such as S-nitrosoglutathione, are potent inducers of the antioxidant protein heme oxygenase 1 (HO-1) (Foresti, R., Clark, J. E., Green, C. J., and Motterlini, R. (1997) J. Biol. Chem. 272, 18411–18417; Motterlini, R., Foresti, R., Bassi, R., Calabrese, V., Clark, J. E., and Green, C. J. (2000) J. Biol. Chem. 275, 13613–13620). Here, we report that Angeli’s salt (AS) (0.25–2mM), a compound that releases nitroxyl anion (NO-) at physiological pH, induces HO-1 mRNA and protein expression in a concentration- and time-dependent manner, resulting in increased heme oxygenase activity in rat H9c2 cells. A time course analysis revealed that NO--mediated HO-1 expression is transient and gradually disappears within 24 h, in accordance with the short half-life of AS at 37 °C (t1⁄2 = 2.3 min). Interestingly, multiple additions of AS at lower concentrations (50 or 100 µM) over a period of time still promoted a significant increase in heme oxygenase activity. Experiments performed using a NO scavenger and the NO electrode confirmed that NO-, not NO, is the species involved in HO-1 induction by AS; however, the effect on heme oxygenase activity can be amplified by accelerating the rate of NO- oxidation. N-Acetylcysteine almost completely abolished AS-mediated induction of HO-1, whereas a glutathione synthesis inhibitor (buthionine sulfoximine) significantly decreased heme oxygenase activation by AS, indicating that sulfydryl groups are crucial targets in the regulation of HO-1 expression by NO-. We conclude that NO-, in analogy with other reactive nitrogen species, is a potent inducer of heme oxygenase activity and HO-1 protein expression. These findings indicate that heme oxygenase can act both as a sensor to and target of redox-based mechanisms involving NO and extend our knowledge on the biological function of HO-1 in response to nitrosative stress.

Trypanosoma cruzi infection triggers substantial production of nitric oxide (NO), which has been shown to have protective and toxic effects on the host's immune system. Sensing of trypomastigotes by phagocytes activates the inducible NO-synthase (NOS2) pathway, which produces NO and is largely responsible for macrophage-mediated killing of T. cruzi. NO is also responsible for modulating virtually all steps of innate and adaptive immunity. However, NO can also cause oxidative stress, which is especially damaging to the host due to increased tissue damage. The cytokines IFN-gamma and TNF-alpha, as well as chemokines, are strong inducers of NOS2 and are produced in large amounts during T. cruzi acute infection. Conversely, TGF-beta and IL-10 negatively regulate NO production. Here we discuss the recent evidence describing the mechanisms by which NO is able to exert its antimicrobial and immune regulatory effects, the mechanisms involved in the oxidative stress response during infection and the implications of NO for the development of therapeutic strategies against T. cruzi.

We propose an integrated model of aqueous outflow control that employs a pump-conduit system in this article. Our model exploits accepted physiologic regulatory mechanisms such as those of the arterial, venous, and lymphatic systems. Here, we also provide a framework for developing novel diagnostic and therapeutic strategies to improve glaucoma patient care. In the model, the trabecular meshwork distends and recoils in response to continuous physiologic IOP transients like the ocular pulse, blinking, and eye movement. The elasticity of the trabecular meshwork determines cyclic volume changes in Schlemm’s canal (SC). Tube-like SC inlet valves provide aqueous entry into the canal, and outlet valve leaflets at collector channels control aqueous exit from SC. Connections between the pressure-sensing trabecular meshwork and the outlet valve leaflets dynamically control flow from SC. Normal function requires regulation of the trabecular meshwork properties that determine distention and recoil. The aqueous pump-conduit provides short-term pressure control by varying stroke volume in response to pressure changes. Modulating TM constituents that regulate stroke volume provides long-term control. The aqueous outflow pump fails in glaucoma due to the loss of trabecular tissue elastance, as well as alterations in ciliary body tension. These processes lead to SC wall apposition and loss of motion. Visible evidence of pump failure includes a lack of pulsatile aqueous discharge into aqueous veins and reduced ability to reflux blood into SC. These alterations in the functional properties are challenging to monitor clinically. Phase-sensitive OCT now permits noninvasive, quantitative measurement of pulse-dependent TM motion in humans. This proposed conceptual model and related techniques offer a novel framework for understanding mechanisms, improving management, and development of therapeutic options for glaucoma.

The endogenous vasodilator nitric oxide (NO) is metabolized in tissues in an O 2 -dependent manner. This regulates NO levels in the vascular wall; however, the underlying molecular basis of this O 2 -dependent NO consumption remains unclear. While cytoglobin (Cygb) was discovered a decade ago, its physiological function remains uncertain. Cygb is expressed in the vascular wall and can consume NO in an O 2 -dependent manner. Therefore, we characterize the process of the O 2dependent consumption of NO by Cygb in the presence of the cellular reductants and reducing systems ascorbate (Asc) and cytochrome P 450 reductase (CPR), measure rate constants of Cygb reduction by Asc and CPR, and propose a reaction mechanism and derive a related kinetic model for this O 2 -dependent NO consumption involving Cygb(Fe 3+ ) as the main intermediate reduced back to ferrous Cygb by cellular reductants. This kinetic model expresses the relationship between the rate of O 2 -dependent consumption of NO by Cygb and rate constants of the molecular reactions involved. The predicted rate of O 2 -dependent consumption of NO by Cygb is consistent with experimental results supporting the validity of the kinetic model. Simulations based on this kinetic model suggest that the high efficiency of Cygb in regulating the NO consumption rate is due to the rapid reduction of Cygb by cellular reductants, which greatly increases the rate of consumption of NO at higher O 2 concentrations, and binding of NO to Cygb, which reduces the rate of consumption of NO at lower O 2 concentrations. Thus, the coexistence of Cygb with efficient reductants in tissues allows Cygb to function as an O 2 -dependent regulator of NO decay.

A plethora of publications on techniques and methodologies for measuring nitric oxide (NO) or reaction products of NO (NO metabolites) has served in recent years to complicate and confuse the majority of researchers interested in this field. Here, we provide a practical approach and summarize the key issues and corresponding solutions regarding quantification with the use of ozone-based chemiluminescence, which is the most accurate, sensitive, and widely used NO detection method. We have drawn on the vast experience of leaders in the field to produce this consensus, but the views and implications presented herein represent our own, and we limit our advice to those techniques with which we have direct experience. Hopefully, this guide will allow authors to make more informed decisions regarding NO metabolite measurement methodology, without the need for each subsequent group to rediscover previously observed advantages and pitfalls.