A novel in vitro membrane oxygenator circuit was developed to test gas exchange where particular elements could be examined whilst keeping other variables constant. The circuit comprises two membrane oxygenators connected to form a continuous blood circuit resembling venous and arterial blood conditions. The effects of Isoflurane, a volatile anaesthetic, on oxygen transfer were investigated. RBC resistance to nitric oxide diffusion (DNO) was tested in this circuit by haemolysis and addition of the haemoglobin-based-oxygen-carrier (HBOC) Oxyglobin. The circuit was primed with equine blood flowing at 2.5 l/min. The oxygenator was ventilated with 5 l/min air/oxygen/N2 mix providing a range of FiO2. The deoxygenator received 5 l/min 5% CO2 in N2 with 0.2-0.3 l/min CO2. Isoflurane 1%, NO 4000-16000 ppb and CO 0.03% were added to the oxygenator gas. Uptake of O2, CO2, CO and NO were calculated by gas inlet and outlet concentrations and flow rates. Arterial and venous oxygen dissociation curve (aODC and vODC) comparisons were made. Isoflurane uptake by the circuit blood was evident and 1% Isoflurane did not affect oxygen uptake (p=0.981), aODC or vODC (p=0.311 and p=0.751). Haemolysis did not affect O2 or CO2 transfer but increased DNO (p<0.001). 250ml free Hb solution addition to the circuit increased DNO by 91% (p<0.0001). Addition of 250ml Oxyglobin increased DNO by 143% from 7.41±2.77 to 17.97±1.83 ml/min/mmHg. Oxyglobin caused a right shift of aODC and vODC (p<0.0001) but NO-bound Oxyglobin caused a left vODC shift (p<0.0001). Conclusion: Isoflurane administered via a membrane oxygenator does not affect O2 uptake or carriage in the blood. RBC surroundings provide significant resistance to DNO in circuit tests. Significant uptake of NO by Oxyglobin supports the potential of HBOCs to scavenge endothelial NO in vivo, causing vasoconstriction.

Following pathogen recognition, nitric oxide (NO) is rapidly produced in plants, this small molecule has emerged as a key signal in plant defence responses. S-nitrosylation is the major route of NO signal transduction in plants, a redox-based modification by addition of an NO moiety on cysteine thiol to form an S-nitrosothiol (SNO). S-nitrosoglutathione reductase (GSNOR) regulates cellular levels of S-nitrosylation and displays a key role in regulating the plant defence response. In this context, NO is important to orchestrate both defence gene expression and the hypersensitive response (HR) during attempted microbial infection. However, how the plant immune system recognizes NO and how NO level could elicit plant defence responses are poorly understood. The Arabidopsis thaliana (Arabidopsis) mutant NO overproducing 1 (nox1) was employed to characterize how NO level elicits defence dynamics. In response to microbial infection, resistance (R) gene-mediated defence and basal resistance were found to be compromised in the nox1 mutant relative to wild type Col-0 plants. Interestingly, nox1 mutant exhibit similar levels of HR and pathogen susceptibility to the GSNOR loss-of-function mutant atgsnor1-3. This phenomenon suggests that NO might regulate defence responses via GSNOR-mediated S-nitrosylation. Therefore, the nox1 atgsnor1-3 double mutant was generated and characterized to clarify this hypothesis. Accelerated HR and increased pathogen susceptibility are shown in the double mutant, which implies that increased NO mediated by nox1 and elevated SNOs resulting from atgsnor1-3, are additive with respect to the plant defence response. To identify genes responsible for NO perception, forward genetic screens were developed to identify Arabidopsis mutants with abnormal NO recognition. NO marker genes for genetic screens were identified from both lab and open source microarray data. Two genes, At3g28740 and At1g76600 were selected and experimentally confirmed to be strongly induced by NO. Transgenic Arabidopsis plants were generated carrying a NO reporter cassette, which consist of a luciferase reporter gene (LUC) driven by the promoter of NO marker gene. This forward genetic approach might be a powerful tool to identify genes integral to NO signal transduction. Three C2H2 zinc finger transcription factors (ZnTFs) ZAT7, ZAT8 and ZAT12 were identified as being rapidly and strongly induced by NO donors, which could be modulators of redox/NO-dependent signalling pathway. T-DNA insertion mutants within these ZnTFs have been identified. Basal resistance against Pseudomonas syringae pv tomato (Pst) DC3000 is compromised in all single knockout lines. Therefore, the full characterisation of defence phenotype of these mutants would be necessary to explore the role of these TFs in the plant defence. Furthermore, zat8 mutant is more sensitive to nitrosative stress when compared to wild type Col-0. This suggests that ZAT8 may be involved in protecting plants against nitrosative stress. However, the molecular mechanisms that underpin this function remain to be determined. In conclusion, NO and SNOs might regulate plant disease resistance via distinct pathways. Our work has also established NO-reporter lines to identify genes responsible for NO perception. In addition, three NO-induced ZnTFs have been identified that participate in regulation of basal resistance, which might unveil aspects of NO signalling related to the regulation of transcription.

Title: The role of nitric oxide in the pathophysiology of neurodegenerative diseases Objectives: The main objective of this thesis is to evaluate the effect of nitric oxide on the formation and development of neurodegenerative diseases. Another objective was to determinate, whether NO affects by its impact processes involved in apoptosis in the CNS. Methods: The thesis is prepared in the form of research, drawing from available relevant resources. Results: Nitric oxide is widely applied in the pathophysiology of selected neurodegenerative diseases, either directly or through other reactive nitrogen and oxygen. It also affects other factors that are involved in apoptosis in the CNS. Keywords: Nitric oxide, NMDA receptors, neurodegenerative diseases, excitotoxicity, apoptosis

Pulmonary diffusing capacity for nitric oxide (DLNO) is a relatively new pulmonary function test to assess gas transfer in the lung. To date, there are no prediction equations made for healthy adult African-American (black) subjects. Thus, the purpose of this study was to create prediction equations for DLNO in this ethnic/racial group. A total of 59 healthy subjects (27 males and 32 females) were recruited to perform pulmonary function testing at Georgia State University. They were diverse in age (18-67 yr), height (140-189 cm), and body mass index (17.2-32.3 kg/m2). All subjects completed single-breath maneuvers at rest inhaling 43 ± 4 ppm NO with a standard diffusion mixture. The breath-hold duration was 5.6 ± 0.6 s. Multiple linear regression predicted DLNO based on the subject’s age, height, and sex. The prediction equation for DLNO (mL/min/mmHg) = 0.92·(height in cm) +38.8·(sex) – 0.012·(age2) – 25, where 1 = male, 0 = female for sex. About 77% of the variance in DLNO was accounted for by sex (67%), age2 (7%), and height (4%). The standard error of the estimate in predicting DLNO was 16.3 mL/min/mmHg. Those with higher resting heart rates had a lower DLNO (r =-0.28, p = 0.03) but it was not included in the regression model as it did not enhance the fit. Black males had a 7-10% lower DLNO and black females had a 12-15% lower DLNO compared to matched white subjects. Black males of the same age and height had a 10% smaller alveolar volume, while black females had a 15% lower alveolar volume compared to matched white subjects. In conclusion, DLNO values and alveolar volumes are reduced in blacks compared to matched whites. The regression model presented best predicts DLNO in African-Americans below 40 years of age.

Doctor of Philosophy / Department of Anatomy and Physiology / Timothy I. Musch / Nitric oxide (NO) is synthesized via distinct NO synthase (NOS) enzymes and constitutes an essential cardiovascular signaling molecule. Whereas important vasomotor contributions of endothelial NOS (eNOS) have been well-described, the specific vasomotor contributions of nNOS-derived NO in healthy subjects during exercise are unknown. The purpose of this dissertation is to test the global hypothesis that nNOS-derived NO is a critical regulator of exercising skeletal muscle vascular control. Specifically, we utilized the selective nNOS inhibitor S-methyl-L-thiocitrulline (SMTC) to investigate the effects of nNOS-derived NO on skeletal muscle vascular function within established rodent models of exercise performance. The first investigation (Chapter 2) identifies that nNOS inhibition with SMTC increases mean arterial pressure (MAP) and reduces rat hindlimb skeletal muscle blood flow at rest whereas there are no effects during low-speed (20 m/min) treadmill running. In Chapter 3 it is reported that nNOS inhibition with SMTC reduces blood flow during high-speed treadmill running (>50 m/min) with the greatest relative effects found in highly glycolytic fast-twitch muscles and muscle parts. Chapter 4 demonstrates that nNOS-derived NO modulates contracting skeletal muscle blood flow (increases), O2 consumption (VO2, increases), and force production (decreases) in the rat spinotrapezius muscle and thus impacts the microvascular O2 delivery-VO2 ratio (which sets the microvascular partial pressure of O2, PO2mv, and represents the pressure head that drives capillary-myocyte O2 diffusion). In Chapter 5 we report that systemic administration of the selective nNOS inhibitor SMTC does not impact lumbar sympathetic nerve discharge. This reveals that the SMTC-induced peripheral vascular effects described herein reflect peripheral nNOS-derived NO signaling as opposed to centrally-derived regulation. In conclusion, nNOS-derived NO exerts exercise-intensity and muscle fiber-type selective peripheral vascular effects during whole-body locomotor exercise. In addition, nNOS-derived NO modulates skeletal muscle contractile and metabolic function and, therefore, impacts the skeletal muscle PO2mv. These data identify novel integrated roles for nNOS-derived NO within healthy skeletal muscle and have important implications for populations associated with reduced NO bioavailability and/or impaired nNOS structure and/or function specifically (e.g., muscular dystrophy, chronic heart failure, advanced age, etc.).

Satellite precursor cells are normally quiescent but once activated they support skeletal muscle growth and regeneration by proliferating and differentiating into myoblasts. When an animal suffers from a muscle injury, quiescent satellite precursor cells are activated by nitric oxide (NO). MyoNovin (1-(3,4-Bis-nitrooxy-butoxy)-2-methoxy-benzene), as a NO donor, was developed to provide nitric oxide directly to the skeletal muscle and has been shown to promote satellite cell activation. A potential drawback of the current MyoNovin molecule is its poor water solubility. The aim of this work was to enhance the water-solubility of MyoNovin in order to improve its ease of formulation and possibly enhance its biological activity. The structure of MyoNovin (MN1) was modified with three different functional groups - methanesulfonyl (MN2), benzoic acid (MN3) and acetamide (MN4). The three novel MyoNovin analogs were identified and shown to have similar biological activity as with MyoNovin. All three MyoNovin analogs were found to have better water solubility.#Based on these results, two of the MyoNovin analogs (MN2 and MN3) had much better biological activity with respect to satellite activation and much improved water solubility and may be the most promising candidates for future studies. / May 2015

The principle product of each NOS is nitric oxide. However, under conditions of substrate and cofactor deficiency the enzymes directly catalyze superoxide formation. Considering this alternative chemistry of each NOS, the effects of each single enzyme on key events of atherosclerosis are difficult to predict. Here, we evaluate nitric oxide and superoxide production by all three NOS isoforms in atherosclerosis. ESR measurements of circulating and vascular wall nitric oxide production showed significantly reduced nitric oxide levels in apoE/eNOS double knockout (dko) and apoE/iNOS dko animals but not in apoE/nNOS dko animals suggesting that eNOS and iNOS majorly contribute to vascular nitric oxide production in atherosclerosis. Pharmacological inhibition and genetic deletion of eNOS and iNOS reduced vascular superoxide production suggesting that eNOS and iNOS are uncoupled in atherosclerotic vessels. Though genetic deletion of nNOS did not alter superoxide production, acute inhibition of nNOS showed that nNOS contributes significantly to superoxide production. In conclusion, uncoupling of eNOS occurs in apoE ko atherosclerosis but eNOS mediated superoxide production does not outweigh the protective effects of eNOS mediated nitric oxide production. We show that although nNOS is not a major contributor of the vascular nitric oxide formation, it prevents atherosclerosis development. Acute inhibition of nNOS showed a significant reduction of superoxide formation suggesting that nNOS is uncoupled. The exact mechanism of action of nNOS in atheroprotection is yet to be elucidated. Genetic deletion of iNOS reduced NADPH oxidase activity. Thus, iNOS has both direct and indirect proatherosclerotic effects, as it directly generates both nitric oxide and superoxide simultaneously resulting in peroxynitrite formation and indirectly modulates NADPH oxidase activity. We hypothesize that eNOS is coupled in the disease free regions of the vessel and contributes to nitric oxide generation whereas in the diseased region of the vessel it is uncoupled to produce superoxide (Figure 16). nNOS expressed in the smooth muscle cells of the plaque contributes to the local superoxide generation. iNOS expressed in smooth muscle cells and leukocytes of the plaque generates superoxide and nitric oxide simultaneously to produce the strong oxidant peroxynitrite. / Stickstoffmonoxid (NO) ist das prinzipielle Produkt aller Stickstoffmonoxid-Synthasen (NOS). Im Falle eines Mangels an Substrat (L-arginin) und Kofaktoren (Tetrahydrobiopterin, BH4) katalysieren die NOS-Enzyme direkt Superoxid (O2-). Diese Veränderung in der Radikalproduktion wird auch als Entkopplung der NOS bezeichnet. Die alternative Produktion von NO oder O2- durch die NOS bedingen, dass eine Voraussage über die Schlüsselfunktion der einzelnen Enzyme in der Entstehung der Atherosklerose schwierig ist. In unserer Studie evaluieren wir die Produktion von NO sowie O2- in atherosklerotischen Läsionen von apoE ko Mäusen und apoE/NOS doppel knockout (dko) Mäusen denen jeweils eine NOS-Isoform fehlt. Elektronen Spin Resonanz (ESR) Messungen konnten eine signifikante Reduktion sowohl des zirkulierenden, als auch der Gefäßwand eigenen Produktion von NO in apoE/eNOS dko und apoE/iNOS dko Mäusen zeigen, nicht jedoch in apoE/nNOS dko Mäusen. Dies lässt darauf schließen, dass eNOS und iNOS den hauptsächlichen Anteil der vaskulären NO-Produktion in atherosklerotischen Läsionen bewerkstelligen. Die pharmakologische Inhibierung wie auch die genetische Deletion von eNOS und iNOS führten ebenfalls zu einer reduzierten vaskulären O2- produktion, was die partielle Entkopplung beider Enzyme in atherosklerotisch veränderten Gefäßen nahe legt. Obwohl die chronische genetische Deletion von nNOS in apoE/nNOS dko die O2- Produktion nicht verändert, zeigte sich bei der akuten pharmakologischen Inhibierung von nNOS (durch L-NAANG) eine maßgebliche Beteiligung von nNOS an der O2- produktion in apoE ko Mäusen. Schlussfolgernd lässt sich sagen, dass in atherosklerotischen Gefäßen von apoE ko Tieren eine Entkopplung von eNOS statt findet, diese jedoch zu keinem Ausgleich der protektiven Effekte der eNOS vermittelten NO-Produktion führt. Unsere Ergebnisse in apoE/nNOS dko Mäusen zeigen eine atheroprotektive Rolle der nNOS, die sich nicht allein durch eine lokale, vaskuläre NO-Produktion durch das Enzym erklären lässt. Wir postulieren weitere systemisch atheroprotektive Eigenschaften der nNOS. Die signifikante Reduktion der Superoxidproduktion durch eine akute Inhibierung der nNOS weist auf eine Entkopplung der nNOS hin. Der exakte Wirkungsmechansimus von nNOS in der Atheroskleroseprävention ist weiterhin noch zu eruieren. Die genetische Deletion von iNOS führt zu einer reduzierten Aktivität der NADPH-Oxidase. Demnach sind für iNOS direkte sowie indirekte atherosklerosefördernde Effekte anzunehmen, da sie auf direktem Wege gleichzeitig NO und O2- produziert, was in einer Peroxynitritbildung resultiert. Wir stellen die Hypothese auf, dass eNOS in den läsionsfreien Gefäßregionen gekoppelt ist und dort seine atheroprotektiven Effekte durch die NO-Produktion vermittelt, während die eNOS in atherosklerotischen Läsionen entkoppelt vorliegt und hier O2- produziert (Fig. 16). iNOS, welches vor allem in den Plaques, in glatten Muskelzellen und Leukozyten zu finden ist, produziert gleichzeitig hohe Konzentrationen von O2- und NO, die als gemeinsames Endprodukt das stark oxidierende Peroxynitrit ergeben und die von uns dokumentierte proatherosklerotische Wirkung der iNOS vermittelt.

O hormônio melatonina produzido pela glândula pineal no período de escuro, participa na regulação circadiana de processos, fisiológicos e fisiopatológicos envolvendo vasos sanguíneos. Alguns destes estudos sugerem que as células endoteliais, que revestem os vasos sanguíneos são alvo para a melatonina circulante e medeiam a regulação do tônus vascular, em condições fisiológicas, e da interação neutrófilo-endotélio, em resposta a um estímulo injuriante. O óxido nítrico produzido pelas células endoteliais é um dos responsáveis por grande parte dos eventos vasculares, e a melatonina inibe a produção de óxido nítrico em diversos modelos. O objetivo deste estudo foi verificar o efeito da melatonina na produção de óxido nítrico induzido por bradicinina em células endoteliais em cultura. Para tanto, utilizamos uma técnica de cultura primária de células endoteliais de rato e através de um marcador fluorescente de óxido nítrico intracelular, mensuramos a fluorescência em microscópio confocal. Foi verificado que a melatonina e seu precursor N-acetilserotonina inibem a produção de óxido nítrico induzido por bradicinina e este efeito não ocorre pela inibição do aumento de cálcio que induz a produção de óxido nítrico. O análogo de receptores MT2 (4P-PDOT) e MT3 (5-MCA-NAT) não provocaram qualquer alteração sobre o aumento de óxido nítrico induzido por bradicinina, e a utilização do antagonista de receptores MT1 e MT2 (luzindol) não reverteu o efeito inibitório da melatonina. Portanto, nossos dados indicam que o efeito da melatonina sobre a atividade da NOS constitutiva não é mediado por receptores de membrana. Considerando que a melatonina é capaz de ligar-se à calmodulina, inibindo desta maneira a atividade da NOS endotelial constitutiva, poderíamos sugerir que este seria o mecanismo de ação. No entanto, é preciso ressaltar que tal atividade não é comprovada para a N-acetilserotonina, assim, apesar de ser este um possível mecanismo de ação, há a necessidade de demonstrar que a N-acetilserotonina está se ligando a calmodulina extraída de células endoteliais. Em resumo, neste trabalho mostramos que a melatonina em concentrações compatíveis com o pico noturno encontrado na circulação, pode modular eventos vasculares no organismo, através da inibição da produção de óxido nítrico em células endoteliais induzida por bradicinina. / Melatonin, the hormone synthesized by the pineal gland at night, signalizes darkness and modulates, in a circadian basis, blood vessels activity. Previous studies suggest that endothelial cells are the target for circulating melatonin and mediate changes in vascular tone and leukocyte-endothelial adherence properties. Melatonin effects can be mediated by several pathways, such as G protein-coupled receptors (MT1 and MT2 receptors), a putative membrane receptor, most probably an enzyme-binding site (MT3 receptor), and several intracellular mechanisms, including calmodulin binding and inhibition of constitutive and induced nitric oxide synthase. The aim of the present study was to characterize melatonin effect on the production of nitric oxide by bradykinin-stimulated endothelial cells in culture. Nitric oxide production was measured in real time at cellular level by detecting fluorescent stimulation of the probe DAF by confocal microscopy. After determining the ideal conditions for recording cumulative dose-response curves for bradykinin (1 – 100 nM) the effect of pre-incubated (1 min) melatonin and analogs was evaluated. Melatonin and its precursor, N-acetylserotonin, but not the selective ligands for receptors MT2 (4P-PDOT) and MT3 (5-MCA-NAT) receptors inhibited bradykinin-stimulated nitric oxide production. This effect was not blocked by the classical antagonist of MT1 and MT2 receptors, luzindol; excluding therefore the participation of membrane receptors. Taking into account that melatonin inhibits calmodulin activation of several enzymes, including constitutive nitric oxide synthase in brain and cerebellum, it could be suggested a similar mechanism for endothelial cells. However, this hypothesis is discussed taking into account that N-acetylserotonin was shown to do not bind neural cells calmodulin. In addition, here we discuss the relevance of the present finding according to physiological and physiopathological roles of endothelial nitridergic system. This analysis point melatonin modulation of constitutive nitric oxide synthase activity as a putative mechanism for explaining melatonin control of vascular tone.

A melatonina é produzida pela glândula pineal somente durante o escuro e atinge rapidamente a circulação, além disso, outros tecidos e células são capazes de produzir melatonina. As células endoteliais, devido a sua localização, são excelentes alvos para as ações da melatonina. O entendimento dos mecanismos de ação pelos quais a melatonina desenvolve seus efeitos sobre as células endoteliais, possibilitaria o uso desta indolamina e de seus análogos como uma importante ferramenta farmacológica. No presente trabalho, demonstramos que a melatonina em concentrações compatíveis com as encontradas na circulação durante o pico noturno de produção pela pineal, atua sobre as células endoteliais inibindo a produção de NO proveniente da enzima constitutiva (eNOS), enquanto altas concentrações de melatonina, que podem ser atingidas por exemplo pela produção por células imunocompetentes ativadas, inibem a produção induzida de NO mediada pela iNOS. A melatonina (1 nM) inibe a produção constitutiva de NO induzida por agonistas que atuam através da ativação de receptores acoplados à proteína G (histamina, carbacol e ATP/P2Y), e este efeito deve-se à inibição do aumento de [Ca2+]i por liberação de estoques intracelulares, sendo independente da ativação de receptores de melatonina. A melatonina inibe os efeitos decorrentes da produção de NO induzida por bradicinina como a produção de GMPc por células endoteliais e a vasodilatação de arteríolas \"in vivo\". A melatonina inibe a produção de NO induzida por LPS também de maneira independente da ativação de seus receptores, porém, em concentrações muito maiores (1-10 µM) do que a necessária para inibir a produção constitutiva. Estes efeitos devem-se à inibição da expressão da enzima iNOS por impedir a translocação do NF-kB ao núcleo. A vasodilatação de aortas induzida por LPS também é inibida por melatonina. Podemos concluir até o momento que as células endoteliais, devido a sua localização, são excelentes sensores para as ações da melatonina e podem auxiliar no melhor entendimento do conceito \"eixo imune-pineal\". Os estudos sobre os mecanismos pelos quais a melatonina atua em condições fisiológicas e fisiopatológicas são essenciais para se conhecer o potencial terapêutico da melatonina. / Melatonin, the darkness hormone, produced at night by the pineal gland, is also synthesized in a non-rhythmic manner by other cells. Pineal and extra-pineal melatonin reaches endothelial layer, and the understanding of its mechanism of action will improve the possibilities of using this indolamine and derivates as pharmacological tools. Here we showed that melatonin, in concentrations compatible to nocturnal melatonin surge impairs the activity of eNOS, while much higher concentrations, which can be attained by activated immune competent cells, impair the induction of iNOS synthesis. As a consequence of inhibiting eNOS we showed that melatonin inhibits vasodilation of the microcirculation induced by bradykinin. The inhibitory effect of melatonin is observed only when eNOS is activated by triggering G protein-coupled receptors (bradykinin B2, muscarinic and P2Y purine receptors). Activation of eNOS by calcium-channel operated receptors (P2X) is not blocked by melatonin. Inhibition of the transcription of iNOS results in inhibition of the LPS-induced vasodilation of rat aorta. As a matter of fact, here we show that LPS effect is dependent on the endothelial layer. The mechanism of action of melatonin in inhibiting iNOS transcription is due to block of the NF-kB pathway. Our work contributed to unravel the role of endothelium cells as targets for melatonin and as a key player in the \"immune-pineal axis\". The understanding of the concentrations ranges reached by endogenous production, i.e., the discrimination between the levels achieved during physiological and physiopathological responses, are essential for using these substances as analogous therapeutical tools.

O Óxido Nítrico inalatório (iNO) é uitlizado para tratamento de várias doenças pulmonares, porém algumas evidências apóiam que esses efeitos farmacológicos do iNO podem alcançar outros leitos vasculares. Desse modo, esse estudo tem como objetivo investigar o possível efeito anti-inflamatório do iNO no modelo de edema de pata induzido por carragenina em camundongos e identificar por qual via ele desempenha essa resposta. Concluimos que o iNO foi eficaz na redução de sinais inflamatórios e houve indícios que o NO desempenha seus efeitos pela via do GMPc, pelo fato de ter aparecido um efeito potencializador na redução do edema quando associoado ao sildenafil e não com o rolipram. Esses resultados indicam que a terapia com iNO vai além dos efeitos vasculares pulmonares inicialmente descritos. / Inhaled Nitric Oxide (iNO) is useful to treat many lung diseases, but some evidences support that these pharmacological effects of iNO can reach other vasculature, beyond the pulmonary vasculature. Thus, this study aimed to investigate the possible antiinflammatory effect of inhaled nitric oxide on the mice paw edema induced by carrageenan and investigate for which way iNO is acting. We conclude that iNO was effective in reducing inflammatory signs and there are some traces that this responses occurred by cGMP way. These results indicate that the beneficial effect of inhaled nitric oxide therapy goes beyond the initially described pulmonar vascular effects.