Acute thrombo-embolic occlusion of the superior mesenteric artery (SMA) with intestinal infarction is a lethal disease, difficult to diagnose in time, with unknown incidence and cause-specific mortality. The aim of this thesis was to characterize the disease and to develop diagnostic methods. Two laboratory studies were conducted on patients with suspected acute SMA occlusion. A pilot-study showed that the fibrinolytic marker D-dimer was elevated in six patients with the disease. In the subsequent study including 101 patients, D-dimer was the only elevated coagulation marker in nine patients with the disease. In a prospective study 24 patients (median age 84 years) were identified, of whom four were diagnosed at autopsy, despite an autopsy-rate of 10%. One-fourth were initially nursed in non-surgical wards. Length of the intestinal infarction was a predictor for death. An analysis of patients from the three studies showed that D-Dimer was elevated in all 16 tested patients with the disease. Sixty patients with acute SMA occlusion underwent intestinal revascularisation and were registered in the Swedish Vascular Registry (SWEDVASC). One-year survival-rate was 40%. Previous vascular surgery was a negative risk-factor. A population-based study was conducted in Malmö, based on an autopsy-rate of 87%. Among 270 patients with the disease, 2/3 were diagnosed only at autopsy and 1/2 were managed in non-surgical wards. The incidence was 8.6 per 100000 person years. The age-standardized incidence increased exponentially without gender differences. The diagnosis was the cause of death in 1.2% among octogenarians and beyond. Thrombotic occlusions were located proximally within the SMA and associated with extensive intestinal infarctions. Synchronous embolism, often multiple, occurred in 2/3 of the patients with embolic occlusions. Conclusions: A normal D-dimer at presentation most likely excludes the diagnosis. Acute SMA occlusion was more frequent than previously estimated from clinical series. The patients were often nursed in non-surgical wards.

One of the main obstacles to maintaining patients with short bowel syndrome on parenteral nutrition, or successfully transplanting these patients with a small bowel graft, is the many severe infections that occur. Evidence is accumulating that translocating bacteria from the patient’s bowel causes a significant part of these infections. In this thesis bacterial translocation is studied in a Thiry-Vella loop of defunctionalised small bowel in the rat. Bacterial translocation to the mesenteric lymph nodes (MLNs) occurs in almost 100% of the rats after three days. No systemic spread of bacteria is observed unless there is additional immunosupression with depletion of Kupffer cells in the liver. However, blocking the function of α/β T cells does not increase the translocation. Removal of MLNs does not either aggravate bacterial translocation in the Thiry-Vella loop model. Conversely, after small bowel transplantation translocating bacteria spread systemically if the MLNs are removed. The Thiry-Vella loop should also be a suitable model for the testing of potentially translocation-inhibiting substances. Reinforcement of the intestinal barrier with glutamine or phosphatidylcholine proved insufficient in decreasing bacterial translocation. Even selective bowel decontamination with tobramycin failed to abolish bacterial translocation. Thus, it seems that the driving force for translocation in this model is strong regardless of the relatively small trauma of intestinal defunctionalisation. Flow cytometric studies of the immune cells in the spleen MLNs showed a decrease in MHC class II positive T cells in the MLNs of the Thiry-Vella loop. Concurrently the number of macrophages increased with time as observed by immunohistochemistry. The fraction of MHC class II negative macrophages increased in the spleens of rats treated with glutamine. In conclusion, the Thiry-Vella loop model offers possibilities of immunological as well as mechanistic studies on bacterial translocation from small intestine.

En dépit du nombre croissant d’études cliniques sur le canal artériel (CA), des failles méthodologiques entretiennent plusieurs incertitudes concernant l’efficacité et la sécurité des traitements chez les bébés nés prématurés. L’objectif de cette recherche était de comparer les concentrations de prostaglandine E2 (PGE2) et les mesures du flux mésentérique par échographie Doppler chez les enfants nés prématurément et ayant un canal artériel traité à l’ibuprofène par voie intraveineuse ou entérale, en utilisant la méthodologie randomisée contrôlée et à double insu. Dans notre étude pilote, 20 nouveau-nés prématurés de moins de 34 semaines ayant un CA symptomatique confirmé par échocardiographie, furent randomisés au traitement à l’ibuprofène par voie intraveineuse ou entérale. La voie d’administration fut maintenue à l’insu de l’équipe traitante, des cardiologues et des investigateurs. Des dosages des prostaglandines plasmatiques ont été mesurés avant le début du traitement ainsi que 3, 24 et 48 h après le début du traitement. Les mesures du flux mésentérique ont été effectuées avant le traitement à l’ibuprofène ainsi que 1 h et 3 h après le traitement. Nous avons démontré à partir de nos observations que les niveaux plasmatiques de prostaglandines E2 diminuent chez les patients ayant répondu au traitement à l’ibuprofène, indépendamment de la voie d’administration. Nous n’avons pas observé de changement dans l’évolution des dosages de PGE2 chez les patients qui n’ont pas répondu au traitement. Les paramètres mesurés par échographie Doppler au niveau de l’artère mésentérique supérieure n’étaient pas affectés par la voie d’administration du traitement à l’ibuprofène, intraveineuse ou entérale. La présente étude suggère ainsi que le traitement du CA par ibuprofène intraveineux ou entéral n’influe pas sur le flux sanguin mesuré par échographie Doppler. La baisse de la prostaglandine E2 coïncide avec la fermeture du CA, et son dosage pourrait jouer un rôle dans la gestion du traitement. Nous avons démontré la faisabilité d’une étude clinique randomisée à double insu dans le traitement du canal artériel; une méthodologie qui devrait désormait être employé dans la recherche clinique sur les traitements de la persistance du CA. / Despite the growing body of research on the patent ductus arteriosus (PDA), issues with clinical research methodology impairs much of our understanding regarding treatment efficacy and safety in the preterm population. The purpose of this study was to determine plasma prostaglandin E2 (PGE2) concentrations in preterm infants with symptomatic persistence of the ductus arteriosus treated with IV and oral ibuprofen, and measure Doppler flow parameters in the superior mesenteric artery, utilizing randomized controlled and double-blind methodology. Twenty patients age < 34 wks with a symptomatic PDA confirmed by echocardiography randomized to oral vs intravenous ibuprofen regimen. Treating physician, cardiologists and study investigators were blinded to treatment allocation. Plasma PGE2 levels were measured prior to ibuprofen treatment and at 3, 24 and 48 h after treatment. Mesenteric Doppler measurements were taken prior to ibuprofen treatment, and 1 h and 3 h after treatment. Our results showed that plasma PGE2 levels decreased over time in patients that exhibited ductal closure after IV or oral ibuprofen treatment; no time-dependent changes in PGE2 were seen in subjects that failed to respond to ibuprofen. Superior mesenteric artery Doppler flow measurements were not affected by ibuprofen treatment (IV or oral), regardless of efficacy on ductal closure and of PGE2 changes. We conclude that treatment with oral or intravenous ibuprofen does not impact on superior mesenteric artery blood flow measured by Doppler ultrasound. Decreases in plasma PGE2 concentrations coincide with ibuprofen efficacy, and may be more cost-effective to monitor than ultrasound. This study also demonstrated the successful use of double blinded randomized controlled research methodology, which should be more strictly applied in future clinical research on PDA treatment.

Anatomical variants of hepatic arteries are frequent. One of the most common origins of aberrant (atypically branching) hepatic arteries is superior mesenteric artery. Many physiologic and pathologic features influence hemodynamics of the latter artery. There were some sporadic cases in literature about the influence of aberrant hepatic artery arising from superior mesenteric artery to the hemodynamics of the latter artery, but no evidence based large extent studies were performed. Therefore the aim of this study was to evaluate how significant the aberrant hepatic artery branching from the superior mesenteric artery influences the hemodynamics of superior mesenteric artery. Anatomical variants of the hepatic arteries were evaluated by computed tomography angiography also the candidates for Doppler ultrasound were selected. Doppler ultrasound was used to evaluate the hemodynamics of the superior mesenteric artery in patients with aberrant hepatic artery arising from the superior mesenteric artery and in those with typical hepatic artery anatomy. The influence of the aberrant hepatic artery arising from superior mesenteric artery to the hemodynamics (resistance) of the superior mesenteric artery was assessed. The results of the investigation show that anatomical variants of the hepatic arteries are frequent. The aberrant hepatic artery arising from superior mesenteric artery significantly lowers resistance of the superior mesenteric artery. Practical recommendations were set... [to full text] / Kepenų arterijų anatominiai variantai yra dažni. Viena dažniausių aberantinių (netipiškai atsišakojančių) kepenų arterijų atsišakojimo vietų yra viršutinė pasaito arterija. Pastarosios arterijos kraujotaka yra įtakojama daugybės fiziologinių ir patologinių veiksnių. Literatūroje taip pat aprašyti pavieniai atvejai apie iš viršutinės pasaito arterijos atsišakojančios aberantinės kepenų arterijos įtaką viršutinės pasaito arterijos hemodinamikai, tačiau didesnės apimties įrodymais pagrįstų tyrimų šioje srityje iki šiol nebuvo atlikta. Todėl šio tyrimo tikslas buvo įvertinti, ar aberantinė kepenų arterija, atsišakojanti iš viršutinės pasaito arterijos, reikšmingai įtakoja pastarosios kraujagyslės hemodinamiką. Šiame tyrime kompiuterinės tomografijos angiografijos pagalba įvertinti kepenų arterijų anatominiai variantai, atrinkti pacientai doplerio ultragarso tyrimams. Pastaruoju metodu tirta viršutinės pasaito arterijos kraujotaka pacientams, kurių vieni turėjo aberantinę kepenų arteriją, atsišakojančią iš viršutinės pasaito arterijos, o kiti turėjo įprastą kepenų arterijų anatomiją. Vertinta aberantinės kepenų arterijos, atsišakojančios iš viršutinės pasaito arterijos, įtaka pastarosios arterijos hemodinamikai (rezistentiškumui). Remiantis tyrimo duomenimis nustatyta, kad kepenų arterijų anatominiai variantai yra dažni. Aberantinė kepenų arterija, atsišakojanti iš viršutinės pasaito arterijos, reikšmingai mažina pastarosios arterijos rezistentiškumą. Pateiktos praktinės... [toliau žr. visą tekstą]

Made available in DSpace on 2015-05-14T12:59:25Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1262940 bytes, checksum: 3eb5eef404a585e59e9d6b96edc0609c (MD5) Previous issue date: 2011-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The pharmacological effects induced by CH2Cl2/MeOH extract (EDP) and Hexane/EtOAc phase (FDP) from the Brazilian alga Dictyota pulchella were studied on the cardiovascular system of Wistar rats using a combined in vivo and in vitro approach. All protocols in this study were approved by the CEPA/LTF (protocol nº 0208/10). In normotensive conscious male rats, EDP injections (5; 10; 20 and 40 mg/kg, i.v., randomly) produced hypotension (-4.1 ± 1.34; -7.0 ± 2.4; -46.9 ± 1.3 and - 54.8 ± 4.3%; respectively) and bradycardia (-2.1 ± 1.6; -4.0 ± 2.3; -66.8 ± 5.2 and - 74.7 ± 4.5%; respectively) (n=5). Isolated superior mesenteric artery rings (1-2 mm) were suspended by cotton threads for isometric tension recordings in a Tyrode s solution at 37 ºC, gassed with a 95% O2 and 5% CO2, under a resting tension of 0.75g. In phenylephrine (Phe, 1&#956;M)-pre-contracted rings, EDP (0.01 500 &#956;g/mL) induced a concentration-dependent relaxation (Maximum Response = 101.4 ± 4.5%; EC50 = 22.35 ± 5.09 &#956;g/mL) and this effect was not modified by removal of the vascular endothelium (MR = 103.3 ± 8.3%; EC50 = 21.43 ± 8.98 &#956;g/mL, n=7). Similar results were found in the presence of FDP (0.01 500 &#956;g/mL). FDP induced a concentration-dependent vasodilatation in both endothelium-intact (MR = 80.6 ± 5.8%; EC50 = 24.1 ± 8.95 &#956;g/mL, n=6) or endothelium-denuded mesenteric artery rings (MR = 95.6 ± 7.5%; EC50 = 23.7 ± 5.65 &#956;g/mL, n=6). Based on the preliminary results, the subsequent experiments were performed in rings without endothelium. To appreciate the involvement of potassium channels, the preparations were preincubated with Tyrode s modified solution, KCl (20 mM) or with non-selective K+ channel blocker, tetraethylammonium (TEA, 3 mM). In both preparations the vasorelaxant activity was not changed. In the presence of a tromboxane A2 agonist U-46619 (100 nM), EDP induced concentration-dependent vasodilatation (MR = 90.3 ± 7.8%; EC50 = 24.63 ± 4.04 &#956;g/mL, n=6) was similar to the response found under Phe-induced. After exposure to high concentrations of extracellular K+ (KCl, 60 mM), the EDP induced concentration-dependent vasodilatation (MR = 97.7 ± 4.0%; EC50 = 34.57 ± 5.11 mg/mL; n=6). In the same experimental condition, FDP induced concentration-dependent vasodilatation (MR = 113.5 ± 6.1%; EC50 = 10.92 ± 2.81 &#956;g/mL; n=6). This result indicates that both EDP and FDP act on voltage-operated calcium channel (Cav). Furthermore, EDP and FDP (0.03; 0.3; 10; 30 e 100 &#956;g/mL) antagonized CaCl2-induced contractions. The extract also induced vasodilatation in the contraction evoked by L-type Ca2+ channel agonist (Bay K 8644, 200 nM) (MR = 113.3 ± 6.7%; EC50 = 19.45 ± 6.66 &#956;g/mL, n=7). These results suggest that EDP induces hypotension and bradycardia. Both EDP and FDP induce endotheliumindependent vasodilatation that involves the inhibition of the Ca2+ influx through blockade of Cav. / Os efeitos farmacológicos do extrato CH2Cl2:MeOH (EDP) e fase Hexano:AcOEt (FDP) da alga marinha brasileira Dictyota pulchella foram estudados sobre o sistema cardiovascular de ratos, utilizando uma abordagem in vivo e in vitro. Em ratos normotensos não anestesiados, EDP (5; 10; 20 e 40 mg/kg, i.v., randomicamente) promoveu hipotensão (-4,1 ± 1,34; -7,0 ± 2,4; -46,9 ± 1,3 e -54,8 ± 4,3%, respectivamente) acompanhada de bradicardia (-2,1 ± 1,6; -4,0 ± 2,3; -66,8 ± 5,2 e - 74,7 ± 4,5%, respectivamente) (n=5). Em anéis de artéria mesentérica superior isolada de rato pré-contraídos com Fenilefrina (FEN) 1 &#956;M, EDP (0,01 500 &#956;g/mL) promoveu um efeito vasorrelaxante dependente de concentração na presença do endotélio vascular (Emáx = 101,4 ± 4,5%; CE50 = 22,35 ± 5,09 &#956;g/mL), e este efeito não foi alterado após a remoção do endotélio (Emáx = 103,3 ± 8,3%; CE50 = 21,43 ± 8,98 &#956;g/mL) (n=7). Resultados semelhantes foram obtidos na presença de FDP (0,01 500 &#956;g/mL), observando-se um vasorrelaxamento tanto na presença (Emáx = 80,6 ± 5,8%; CE50 = 24,1 ± 8,9 &#956;g/mL), quanto na ausência do endotélio funcional (Emáx = 95,6 ± 7,5%; CE50 = 23,70 ± 5,65 mg/mL). Para avaliar se o efeito de EDP era dependente do tônus vascular, este extrato foi testado no tônus basal, na presença ou ausência do endotélio, demonstrando que a resposta não foi alterada em nenhuma das duas situações. Baseado nos resultados preliminares, os experimentos subseqüentes foram realizados com endotélio desnudo. Para avaliar a participação dos canais para potássio (K+), utilizou-se uma solução com 20 mM de KCl ou tetraetilâmonio (TEA) 3 mM. Em ambas as preparações (Emáx = 102,3 ± 4,8%; CE50 = 25,40 ± 6,05 &#956;g/mL) ou (Emáx = 111,2 ± 5,3%; CE50 = 16,70 ± 3,61 &#956;g/mL) (n=7), respectivamente, a atividade vasorrelaxante de EDP não foi alterada. Na presença de outro agente contracturante, U46619 (100 nM), EDP promoveu um efeito vasorrelaxante (Emáx = 90,3 ± 7,8%; CE50 = 24,63 ± 4,04 &#956;g/mL) de maneira similar aos anéis pré-contraídos com FEN. Em experimentos contendo uma solução despolarizante de 60 mM de KCl, EDP causou vasorrelaxamento dependente de concentração (Emáx = 97,7 ± 4,0%; CE50 = 34,57 ± 5,11 mg/mL; n=6). Na mesma condição experimental, FDP também promoveu um efeito vasorrelaxante (Emáx = 113,5 ± 6,1%; CE50 = 10,92 ± 2,81 &#956;g/mL; n=6), não havendo diferença significante, para os dois compostos, quando comparados aos anéis pré-contraídos com FEN. Sugere-se que tanto EDP quanto FDP atuem sobre os canais para cálcio sensíveis a voltagem (Cav). Além disso, EDP e FDP (0,03; 0,3; 10; 30 e 100 &#956;g/mL) antagonizaram as contrações induzidas por CaCl2. O extrato ainda produziu vasorrelaxamento na presença de um agonista de canais para Ca2+ tipo-L (Bay K 8644; 200 nM) (Emáx = 113,3 ± 6,7% e CE50 = 19,45 ± 6,66 &#956;g/mL, n=7). Esses resultados sugerem que EDP produz hipotensão e bradicardia transientes, e tanto EDP quanto FDP promovem vasorrelaxamento independente do endotélio vascular por inibição do influxo de Ca2+, por meio do bloqueio dos Cav.

Made available in DSpace on 2015-05-14T12:59:31Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4097090 bytes, checksum: 20afefc885332713d2591aa778f7c7c0 (MD5) Previous issue date: 2012-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The essential oils are volatile organic constituents found in aromatic plants, which present several monoterpenes, such a-terpineol. Studies have demonstrated some biologic activities such as hypotensive and vasorelaxant (Guedes et al., 2004). In the present work the cardiovascular effects of a-terpineol was investigated and the pharmacodynamics of this effect was characterized. Wistar Kyoto and spontaneously hypertensive rats (SHR) were anaesthetized and polyethylene catheters were inserted into the low abdominal aorta and inferior vena cava for blood pressure measurements and administration of drugs. Isolated superior mesenteric rings (1-2 mm) were suspended by cotton threads for isometric tension recordings in Tyrode s solution (37°C, gassed with 95% O2 and 5% CO2), under 0.75g resting tension were measured by using pressure transducers, coupled to a computer set and CVMS software Miobath-4, WPI, Sarasota, EUA. In addition, the bioavailability of NO and eNOS, AKT and AMPK activity were quantified when exposing cells to α-terpineol in the cultured endothelial cells. In both SHR and normotensive rats, i.v. bolus injections of α-terpineol (1 20 mg/kg) decreased mean arterial pressure (MAP) in a dose-related manner, WKY (-103, -399, -5211, -6212 mmHg, n=10) and SHR (-375, -577, -715, -844 mmHg, n=9) associated with tachycardia. However, hypotensive and tachycardic responses were significantly attenuated after L-NAME (20 mg/kg, i.v.). The -terpineol demonstrated improves the baroreflex sensitivity. In intact isolated rat mesenteric rings -terpineol (10-12 10-5M) induced concentration-dependent relaxation of the contractions induced by phylephrine (10M) WKY Emax= 60  4 or SHR Emax= 53.7 ± 3, p<0.05, n=9). After endothelium removal the vasorelaxant elicited by -terpineol was significantly attenuated WKY [Emax= 20.5  1*] and SHR [Emax= 16.1 ± 3*, p<0.05, n=8]. Similar results were obtained in the presence of L-NAME 100M, a competitive antagonist of NOS, hydroxocobalamin 30 μM, a NO scavenger or ODQ 10μM, a selective inhibitor of soluble guanylyl cyclase. In addition, in endothelial cells, a-terpineol increased eNOS activation and NO levels by phosphorylation of PI3K/ AKT and AMPK pathway. However, atropine (1ηM) or indometacin (10 μM) had no effect on the a-terpineol -induced vasorelaxation. Furthermore, vasorelaxation was significantly attenuated in the presence of 20 mM KCl a modulator K+ efflux or several blocking of potassium channels: 1mM 4-aminopirimidine, 10 M glibenclamide, 1 mM tetraethylammonium and carybdotoxin plus apamin (0.2uM). In conclusion, the present study demonstrated that a-terpineol induced hypotensive effect, probably due to a decrease of peripheral vascular resistances, which seems to be mediated by endothelium derived relaxant factors, at least NO induced. These results suggest that vasorelaxant response, almost completely mediated by the endothelium, likely via NO release and activation eNOS by PI3K and AMPK with consequently activation of NO-cGMP pathway and potassium channels activation at least, KCa, KV, and KATP are involved in the vasorelaxant effect induced by a-terpineol. / Os óleos essenciais são componentes voláteis orgânicos encontrados em plantas aromáticas, que apresentam vários monoterpenos, como o α-terpineol. Estudos têm demonstrado algumas atividades biológicas, tais como hipotensivas e vasorelaxantes (Guedes et al., 2004). No presente trabalho, estudaram-se os efeitos cardiovasculares do α-terpineol e caracterizou-se a farmacodinâmica destes efeitos. Para isso foram utilizados ratos normotensos Wistar (WKY) e espontaneamente hipertensos (SHR), empregando técnicas combinadas in vivo, in vitro, e cultivo de células endoteliais. Para determinar a medida direta da pressão arterial, foram implantados cateteres na artéria aorta e veia cava inferior para administração de drogas em ratos WKY e SHR. Adicionalmente, foram realizados estudos para avaliar a reatividade vascular, assim, animais foram sacrificados e a artéria mesentérica superior foi isolada. Os anéis foram mantidos em cubas com solução de Tyrode, e gaseificada com carbogênio. Os anéis foram fixados a um transdutor de força, o qual estava acoplado a um sistema de aquisição de dados (Miobath-4, WPI, Sarasota, EUA) a uma tensão de 0,75 g por 1h. Após este período as preparações, foram pré-contraídas com 10 μM de fenilefrina (FEN) e, em seguida, concentrações crescentes de a-terpineol (10-12-10-5 M) foram adicionadas cumulativamente. Adicionalmente, realizamos experimentos para quantificação da produção de NO e determinação da atividade da eNOS, AKT e AMPK em cultivo de células endoteliais, utilizando as técnicas de citometria de fluxo e western blotting. Assim, observamos que a-terpineol (1, 5, 10 e 20 mg/kg i.v., randomicamente) produziu uma hipotensão dose-dependente em ratos WKY (-103, -399, -5211, -6212 mmHg, n=10) e SHR (-375, -577, -715, -844 mmHg, n=9, respectivamente), associada a taquicardia. A resposta hipotensora foi atenuada significantemente, após o tratamento com L-NAME (20 mg/kg, i.v), sugerindo que esse efeito pode ser decorrente de uma diminuição da resistência periférica., α-terpineol demonstrou melhorar a sensibilidade do barorreflexo. A resposta vasorelaxante foi significativamente atenuada quando comparada aos anéis na presença (WKY Emax= 60  4 e SHR Emax= 53,7 ± 3, p<0,05, n=9) e na ausência do endotélio funcional [WKY Emáx= 20,5  1 e SHR Emáx=16,1 ± 3, p<0,05, n=8]. Em anéis pré-contraídos com FEN na presença de L-NAME (100 μM), Hidroxicobalamina (30 μM) e ODQ (10 μM), a resposta relaxante foi atenuada significantemente, sugerindo uma participação da via NO-GMPc. Adicionalmente, a-terpineol aumentou os níveis de produção de NO e a atividade da eNOS por fosforilar vias como a PI3K e AMPK. No entanto, na presença de atropina (1 mM) ou indometacina (10 uM), a resposta vasorelaxante de a-terpineol não foi alterada indicando que os receptores muscarínicos e metabólitos da enzima Ciclooxigenase parecem não estar envolvidos. KCl (20mM) foi capaz de atenuar o efeito de a-terpineol, e preparações com endotélio vascular incubados com glibenclamida (10 uM) e 4-aminopiridina (1 mM), tetraetilamônio (1 mM) e caribdotoxina + apamina (0,2 μM). Deste modo, concluímos que resposta vasorelaxante promovida pelo a-terpineol é dependente de endotélio e envolve a via L-Arginina-NO-GMPc por aumentar a fosforilação da eNOS por vias PI3K e AMPK, produção de NO e EDHF com participaçãode canais para potássio do tipo KCa, KV e KATP em SHR e WKY e estes efeitos são responsáveis por eventos in vivo.

Made available in DSpace on 2015-05-14T12:59:37Z (GMT). No. of bitstreams: 1 parte1.pdf: 2125844 bytes, checksum: f5e0174d3679c5bce4f74af8ed1b3d4f (MD5) Previous issue date: 2009-08-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Decreased availability of NO in the vasculature promotes the progression of cardiovascular diseases and oximes represents a NO-donor group capable of to restore this defictIn rat superior mesenteric arterial rings, as non-aromatic oximes: diacetylmonoxime and dimetylglycone-oxime, as aromatic oximes: benzofenone-oxime, 4-Cl-benzofenone and cinnamaldheyde-oxime isomeric mixture were markedly less potent than tans-E-cinnamaldheyde-oxime (E CAOx) whose relaxation was concentration-dependent in denuded-endothelum pre-contracted rings with PHE (pD2 = 5,11 ± 0,05), or U46619 (pD2 = 5,03 ± 0,06), an tromboxanic agonist TP, or with A23187 (pD2 = 4,70 ± 0,06), an Ca2+ ionophore, beyond KCl 60mM (pD2 = 4,50 ± 0,06). The relaxation was not modified by endothelium or L-NAME (100 μM, NOS inhibitor), proadifen (30 M; inibidor do citocromos P450), ou de N-acetyl-L-Cysteyn (1 mM e 3 mM; an NO- scavenger). However, was affected by cytochromos P4501A1 and NADPH-dependent reductases inhibitor, 7ethoxyresorufin (7 ER, 10 μM; pD2 = 4,82 ± 0,07), and NO scavenger, PTIO (300 M; pD2 = 4,68 ± 0,11). Demonstrating that E-CAOx induces independent-endothelium relaxation with a possible NO production, mediated by NADPH-dependent reductases. These results corroborate with E-CAOx action of to increase DAF-T fluorescence, in rat aorta smooth miocytes, abolished by 7-ER pre-incubation. Futhermore, the Emax decrease caused by (Rp)-8pCPT-cGMPS (10 M; PKG inhibitor), plus potency reduction by ODQ presence (0,1 M; pD2 = 4,65 ± 0,07 e 10 M; pD2 = 4,41 ± 0,04), a soluble guanylyl-cyclase inhibitor, reforce the pathway NO/cGC/cGMP/PKG participation. On the other hand, the presences of KCl 20mM and TEA (1 mM; pD2 = 4,62 ± 0,04), a BKCa blocker, were capable of the interfering in response, but not 4-AP (1 mM; Kv blocker) and Glibenclamide (10 M; a KATP blocker). In ODQ (10 M) combinations, only KCl 20mM, interpose on Emax, suggesting that K+ channels contribution, majorly BKCa, is sGC-activation dependent. Due relaxing pre-contracted rings: with S(-)BayK 8644 (pD2 = 4,95 ± 0,05), a direct activator of dihydropiridine-sensitive Cav, and rings pre-contracted with PHE in the presence of Niphedipine (1 M), E-CAOx can also to be acting by inhibits Ca2+ influx through dihydropiridine-sensitive Cav or to interfere in contract mechanisms ulterior to Ca2+ entry, as is the case of Na+/Ca2+ exchanger. This hypothesis is justified by reduction in response due the Ni+2 presence (Na+/Ca2+ inhibitor). In conclusion, the data shown that E-CAOx was the more potent oxime investigated with NO production thougth NADPH-dependent reductases action and subsequentely pathway CGs/GMPc/PKG activation associated to BKCa activation, Cav inhibition and exchalenger Na+/Ca2+activation. / Uma diminuição da disponibilidade do NO na vasculatura promove a progressão de doenças vasculares e as oximas representam um grupo de doadores de NO capaz de reestabelecer tal deficiência. Em anéis de artéria mesentérica superior isolada de rato, tanto as oximas não aromáticas: diacetilmonoxima e dimetilglioxima, quanto as oximas aromáticas: benzofenona-oxima, 4 Cl benzofenona-oxima e a mistura isômera de cinamaldeído-oximas foram menos potentes que trans-cinamaldeído-oxima (E-CAOx) cujo relaxamento foi dependente de concentração em anéis pré-contraídos com: FEN (pD2 = 5,11 ± 0,05), um agonista adrenérgico, ou com U46619 (pD2 = 5,03 ± 0,06), um agonista tromboxânico TP, ou com A23187 (pD2 = 4,70 ± 0,06), um ionóforo de íons Ca2+, além de KCl 60mM (pD2 = 4,50 ± 0,06). O relaxamento não foi modificado pela presença do endotélio ou de L-NAME (100 M; inibidor das sintases de NO), proadifeno (30 M; inibidor do citocromos P450), ou de N-acetil-L-cisteína (1 mM e 3 mM; seqüestrador de NO-). Entretanto, foi afetado pela presença do inibidor de citocromos P4501A1 e de redutases dependentes de NADPH, 7-Etoxi-resurofino (7-ER, 10 M; pD2 = 4,82 ± 0,07), e do sequestrador de NO, PTIO (300 M; pD2 = 4,68 ± 0,11). Demonstrando que E-CAOx causa um relaxamento independente de endotélio com possível produção de NO , mediado por redutases dependentes de NADPH. Tais resultados corroboram com a ação de E-CAOx em aumentar a fluorescência emitida por DAF-T, em mióciotos de aorta de rato, abolida pela presença de 7-ER (10 M). Além disso, a diminuição do efeito máximo de E-CAOx causada pela presença de (Rp)-8pCPT-cGMPS (10 M; inibidor da PKG), somada à diminuição da potência causada pelo ODQ (0,1M; pD2 = 4,65 ± 0,07 e 10M; pD2 = 4,41 ± 0,04), um inibidor da ciclase de guanilil solúvel (CGs), reforçam a participação da via NO/CGs/GMPc/PKG. Por outro lado, as presenças de KCl 20mM (pD2 = 4,78 ± 0,04) e de TEA (1 mM; pD2 = 4,62 ± 0,04), um bloqueador de BKCa, foram capazes de interferir na resposta, mas 4-aminopiridina (1 mM; bloqueador de Kv) e Glibenclamida (10 M; bloqueador de KATP) não. Em combinações com ODQ (10M), apenas KCl 20 mM, interferiu no Emax, sugerindo que a contribuição dos canais para K+, principalmente dos BKCa, é dependente da ativação da CGs. Por relaxar anéis pré-contraídos com S(-)BayK 8644 (pD2 = 4,95 ± 0,05), um ativador direto dos Cav sensíveis à diidropiridinas, e anéis pré-contraídos com FEN na presença de nifedipino (1 M; inibidor dos Cav), E-CAOx pode também estar atuando por inibir o influxo de íons Ca2+ ou interferir em mecanismos contráteis posteriores à entrada de Ca2+, como é o caso do trocador Na+/Ca2+. Tal hipótese é justificada pela redução da resposta provocada pela presença do Ni+2 (inibidor do trocador Na+/Ca2+). Em conclusão, os dados demonstram que E-CAOx foi a oxima investigada mais potente e que produz NO via ação das redutases dependentes de NADPH com subseqüente ativação da via CGs/GMPc/PKG associada à ativação dos BKCa, inibição dos Cav e ativação do trocador Na+/Ca2+.

Made available in DSpace on 2015-05-14T12:59:39Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 1442527 bytes, checksum: 9d12b86569a24dac4080acc552110564 (MD5) Previous issue date: 2012-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / It was observed the pharmacological effects of OXDINH, a 1,3,4-oxadiazole derivative obtained by organic synthesis, on the cardiovascular system and the involvement of K+ channels in this response, were studied in rats using techniques combined in vivo and in vitro. In the superior mesenteric artery rings isolated from rats with functional endothelium, OXDINH (10-10 - 10-4 M) induced relaxation of contractions induced by phenylephrine (1 μM) (pD2 = 5.33 ± 0.16, Emax = 117.03 ± 6.49%, n = 7) concentration dependent manner and this effect was not attenuated after removal of the vascular endothelium (pD2 = 5.15 ± 0.09; Emáx = 108.58 ± 6.03%, n = 6). These results suggest that the response induced by vasorelaxant OXDINH seems to be independent of the vascular endothelium. Based on these initial observations, the subsequent experiments were performed with preparations without endothelium. In the preparations incubated with KCl 20mM, a modulator of the efflux of K+, the vasorelaxant effect induced OXDINH was changed (pD2 = 4.67 ± 0.08; Emáx = 57.71 ± 1.72%, n = 5), which is a characteristic of substances that act by activating K+ channels. This effect was corroborated after the use of tetraethylammonium (TEA) 3 mM (Emáx = 44.26 ± 2.41%) that this concentration does not selectively block K+ channels. In addition, the vasodilating effect OXDINH was significantly attenuated after incubation with 4- aminopyridine (1 mM) (Emáx = 61.17 ± 5.55%), glibenclamide (10 μM) (Emáx = 57.00 ± 4.07%), or BaCl2 (30 μM) (Emáx = 61.87 ± 7.52%), selective blockers of KV, KATP and KIR, respectively. By using TEA (1 mM), which at this concentration is more selective for the BKCa, vasodilatation was also found to be significantly attenuated (Emáx = 47.31 ± 5.75%), suggesting the involvement of these channels in this effect. Additionally, when OXDINH (10-5 and 10-4 M) was incubated in depolarizing medium nominally without Ca2+, CaCl2 induced contractions were not changed. However, these contractions were significantly attenuated concentration dependent manner when OXDINH (10-4 M) was incubated in saline without Ca2+ and nominally in the presence of phenylephrine (10μM). In non-anesthetized normotensive rats, OXDINH (1, 5 and 10 mg.kg-1 iv, randomly) produced hypotension accompanied by tachycardia. Interestingly, the highest dose (30 mg.kg-1) of OXDINH, the pressor and tachycardic response was, probably by a direct effect of the compound in the heart. In conclusion, these results suggest that the biological effects induced by OXDINH seem to directly involve the participation of K+ channels, probably by repolarization / hyperpolarization of the membrane and consequent closure of Cav, preventing the influx of Ca2+ through these channels. / Os efeitos farmacológicos de OXDINH, um derivado 1,3,4-oxadiazol obtido por síntese orgânica, sobre o sistema cardiovascular e a participação dos canais para K+ nesta resposta, foram estudados em ratos usando técnicas combinadas in vivo e in vitro. Em anéis de artéria mesentérica superior isolada de rato, com endotélio funcional, OXDINH (10-10 10-4 M) induziu relaxamento das contrações induzidas por fenilefrina (1 μM) (pD2 = 5,33 ± 0,16, Emáx= 117,03 ± 6.49 %, n = 7) de maneira dependente de concentração e esse efeito não foi atenuado após remoção do endotélio vascular (pD2=5,15 ± 0,09, Emáx= 108,58 ± 6.03 %, n = 6). Esses resultados sugerem que a resposta vasorelaxante induzida pela OXDINH parece ser independente do endotélio vascular. Baseado nessas observações iniciais, os experimentos subseqüentes foram realizados com preparações sem endotélio vascular. Em preparações incubadas com KCl 20 mM, um modulador do efluxo de K+, o efeito vasorelaxante induzido por OXDINH foi alterado (pD2= 4,67 ± 0,08, Emáx= 57,71 ± 1.72%, n = 5), sendo esta uma característicade substâncias que agem por ativar canais para K+. Este efeito foi corroborado após utilização de tetraetilamônio (TEA) 3 mM (Emáx= 44,26 ± 2.41%), que nesta concentração bloqueia não seletivamente os canais para K+. Além disso, o efeito vasodilatador do OXDINH foi significativamente atenuado após incubação com 4- aminopiridina 1 mM (Emáx= 61,17 ± 5,55%), glibenclamida 10 μM (Emáx= 57,00 ± 4,07%), ou BaCl2 30 μM (Emáx= 61,87 ± 7.52%), bloqueadores seletivos dos KV, KATP e KIR, respectivamente. Ao utilizar TEA 1 mM, que nesta concentração é mais seletivo para os BKCa, a vasodilatação também foi atenuada de modo significante (Emáx= 47,31 ± 5.75%), sugerindo a participação destes canais neste efeito. Adicionalmente, quando OXDINH (10-5 e 10-4M) foi incubado em meio despolarizante nominalmente sem Ca2+, as contrações induzidas por CaCl2 não foram alteradas. Porém, estas contrações foram significativamente atenuadas, de maneira dependente de concentração, quando OXDINH (10-4M) foi incubado em solução fisiológica nominalmente sem Ca2+ e na presença de fenilefrina (10μM). Em ratos normotensos não anestesiados, OXDINH (1; 5 e 10 mg.kg-1 i.v., randomicamente) produziu uma hipotensão acompanhada por taquicardia. Interessantemente, na maior dose administrada (30 mg.kg-1) de OXDINH, a resposta foi pressora e taquicárdica, provavelmente por um efeito direto do composto no coração. Em conclusão, esses resultados sugerem que os efeitos biológicos induzidos por OXDINH parecem envolver diretamente a participação de canais para K+, provavelmente pela repolarização/hiperpolarização da membrana e, consequente fechamento dos Cav, impedindo o influxo de Ca2+ através desses canais.

Made available in DSpace on 2015-05-14T12:59:40Z (GMT). No. of bitstreams: 1 Arquivototal.pdf: 1615428 bytes, checksum: 4d4de6ab202581287430ca102d9b4037 (MD5) Previous issue date: 2012-02-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The pharmacological effects of ethanol extract (EPC), chloroform phase (FPC) and 5,7,4'-trimethoxyflavone (TMF) from Praxelis clematidea on superior mesenteric artery rings of rats, were studied. Isometric tension experiments revealed that EPC and FPC (0.001 to 1000 μg/mL) promoted concentration-dependent relaxation in mesenteric rings with functional endothelium (EC50 = 27.2 ± 6.4 μg/mL, 41.9 ± 11.8 μg/mL, respectively, n = 7), and these effects were attenuated after removal of the vascular endothelium (EC50 = 141.9 ± 19.4 μg/mL,167.0 ± 30.6 μg/mL, respectively, n = 7), suggesting that both are vasorelaxants secondary metabolites. The TMF (10-12 to 10-3 M), composed mostly isolated FPC, promoted a relaxation in rings with intact endothelium (pD2 = 5.44 ± 0.12, n = 6), concentration dependent manner, with power similar to the effect of quercetin, a flavonoid abundant in the plant kingdom (pD2 = 5.71 ± 0.16, n = 6). After removal of functional endothelium the concentration-response curve for the TMF was shifted to the right, with a decrease in potency, but no change in maximal effect (pD2 = 4.50 ± 0.10, n = 6). The relaxation of the flavonoid was not modified by pre-incubation of indomethacin (10 μM). However, it was attenuated after pre-incubation of L-NAME (100 μM, pD2 = 4.52 ± 0.08, n = 5), PTIO (300 μM, pD2 = 4.62 ± 0.09, n = 5 ) and ODQ (10 μM, pD2 = 4.36 ± 0.11, n = 5) and was reversed in preparations with functional endothelium pre-incubated with L-arginine (1 mM) plus L-NAME (100 μM) (pD2 = 5.85 ± 0.14, n = 5). Demonstrating the non-involvement of COX metabolites and participation of the NOS/NO/CGs pathway in the relaxation produced by TMF. The presence of 20 mM KCl (pD2 = 4.62 ± 0.08, n = 5) and TEA (3 mM; pD2 = 4.28 ± 0.10, n = 5) attenuated the response produced by TMF only in rings with endothelium, demonstrating that this compound produces relaxation through activation of K+ channels to endothelium-dependent. In addition, the use of glibenclamide (10 μM) did not modify the effect of TMF on rings with functional endothelium, but the pre-incubation of 4-aminopyridine (1 mM; pD2 = 4.7 ± 0.08, n = 5) and TEA (1 mM; pD2 = 4.48 ± 0.04, n = 5) attenuated the potency of the flavonoid vasorrelaxant response, suggesting the involvement of the K+ channels to Kv and BKCa type. TMF relaxations in mesenteric rings pre-contracted with 60 mM KCl and inhibited the vasoconstriction induced by CaCl2 concentration dependent manner. The maximum effect of TMF was mitigated by pre-incubation of nifedipine (1 μM, Emáx = 56.0 ± 7.9%, n = 5), indicating that the flavonoid-induced vasodilation is related to the inhibition of the influx of Ca2+ via L-type Cav. In conclusion, these results suggest that the EPC, the FPC and TMF inducing effect vasorrelaxante in mesenteric rings, and that the response produced by the flavonoid involves NOS/NO/CGs pathway, with consequent activation of channels for K+, and inhibition of the influx Ca2+ channels via L-type Cav. / Os efeitos farmacológicos do extrato etanólico (EPC), fase clorofórmica (FPC) e 5,7,4 -trimetoxiflavona (TMF) provenientes de Praxelis clematidea, sobre anéis de artéria mesentérica superior de ratos, foram estudados. Experimentos de tensão isométrica revelaram que EPC e FPC (0,001 1000 μg/mL) promoveram relaxamento dependente de concentração em anéis mesentéricos, com endotélio funcional (CE50 = 27,2 ± 6,4 μg/mL; 41,9 ± 11,8 μg/mL, respectivamente, n=7), e estes efeitos foram atenuados após a remoção do endotélio vascular (CE50 = 141,9 ± 19,4 μg/mL, 167,0 ± 30,6 μg/mL, respectivamente, n=7), sugerindo que ambos possuem metabólitos secundários vasorrelaxantes. O TMF (10-12 a 10-3 M), composto majoritário isolado de FPC, promoveu um relaxamento em anéis com endotélio intacto (pD2= 5,44±0,12, n=6), de maneira dependente de concentração, com potência semelhante ao efeito da quercetina, o flavonóide mais abundante no reino vegetal (pD2= 5,71±0,16, n=6). Após a remoção do endotélio funcional a curva concentração-resposta para o TMF foi deslocada para a direita, com uma diminuição da potência, porém sem alteração no efeito máximo (pD2 = 4,50 ± 0,10, n=6). O relaxamento do flavonóide não foi modificado pela pré-incubação de indometacina (10 μM). Entretanto, foi atenuado após a pré-incubação de L-NAME (100 μM; pD2 = 4,52 ± 0,08, n=5), PTIO (300 μM; pD2 = 4,62±0,09, n=5) e ODQ (10 μM; pD2 = 4,36 ± 0,11, n=5), e foi revertido em preparações com endotélio funcional pré-incubadas com L-arginina (1mM) mais L-NAME (100 μM) (pD2 = 5,85 ± 0,14, n=5). Demonstrando o não envolvimento dos metabólitos da COX e a participação da via NOS/NO/CGs no relaxamento produzido por TMF. A presença de KCl 20 mM (pD2 = 4,62 ± 0,08, n = 5) e TEA (3 mM; pD2 = 4,28 ± 0,10, n=5), atenuou a resposta produzida por TMF, apenas em anéis com endotélio vascular, demonstrando que este composto produz relaxamento por meio ativação de canais para K+, dependente do endotélio. Além disso, a utilização da Glibenclamida (10 μM) não modificou o efeito do TMF em anéis com endotélio funcional, porém a pré-incubação de 4-aminopiridina (1 mM; pD2 = 4,7 ± 0,08, n = 5), e TEA (1 mM; pD2 = 4,48 ± 0,04, n=5) atenuaram a potência da resposta vasorrelaxante do flavonóide, sugerindo o envolvimento dos canais para K+ do tipo Kv e BKca. TMF promoveu relaxamento em anéis mesentéricos pré-contraídos com KCl 60 mM e inibiu a vasoconstrição induzida pelo CaCl2 de maneira dependente de concentração. O efeito máximo de TMF foi atenuado com a pré-incubação de nifedipino (1 μM; Emáx = 56,0 ± 7,9%, n=5), indicando que a vasodilatação induzida pelo flavonóide está relacionada com a inibição do influxo de Ca2+ via Cav tipo L. Em conclusão, estes resultados sugerem que o EPC, a FPC e o TMF induzem efeito vasorrelaxante em anéis mesentéricos, e que a resposta produzida pelo flavonóide envolve a via NOS/NO/CGs, com consequente ativação de canais para K+, e a inibição do influxo de Ca2+ via canais para Cav tipo-L.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Na gravidez a circulação sistêmica materna se adapta para favorecer a perfusão úteroplacentária e o sistema renina-angiotensina (SRA) tem um papel importante nessa adaptação. O objetivo deste estudo foi investigar a contribuição do SRA para a regulação cardiovascular materna no final da gravidez, assim como a via L-arginina-NO-GMPc em plaquetas de ratas normotensas e espontaneamente hipertensas (SHR). O leito arterial mesentérico (LAM) e plaquetas foram obtidos no 20 dia de gravidez de ratas Wistar (NG) e SHR (HG) e respectivos controles em diestro (ND e HD). A pressão arterial sistólica foi reduzida no final da gravidez de ratas NG e HG. Os efeitos vasodilatadores induzidos pela angiotensina II e pela angiotensina 1-7, avaliados em LAM pré-contraído com norepinefrina, foram maiores em ratas HG do que nos outros grupos. A expressão da enzima óxido nítrico sintase (NOS) endotelial, avaliada em LAM pela técnica de Western Blotting, foi maior em NG e HG comparada com os respectivos controles. Enquanto isso, a expressão da enzima conversora de angiotensina (ECA) e dos receptores AT1 se apresentou aumentada em HD comparada aos grupos normotensos e a gravidez levou à redução das expressões em HG. A expressão de ECA2 foi maior nos grupos hipertensos do que dos grupos normotensos. O dano oxidativo, avaliado pela formação de substâncias reativas ao ácido tiobarbitúrico, foi menor em LAM de ratas NG e HG. A atividade da superóxido dismutase foi menor em HG comparada a HD. Enquanto isso, a gravidez aumentou a atividade da catalase em ratas normotensas e aumentou a atividade da glutationa peroxidase em ratas hipertensas. Em suspensão de plaquetas, as expressões de NOS endotelial e induzível, avaliadas por Western Blotting, assim como, a atividade da NOS intraplaquetária, mensurada pela conversão de L-[3H]-arginina a L-[3H]-citrulina, foram reduzidas em NG comparadas a ND, apesar do influxo inalterado de Larginina. Paradoxalmente, os níveis de GMPc foram similares entre ND e NG, assim como a expressão de fosfodiasterase5 (PDE5) e a agregação plaquetária induzida por ADP. Em SHR, o influxo de L-arginina foi reduzido na gravidez. Ratas HG apresentaram menor expressão de NOS induzível e atividade da NOS quando comparadas com ratas HD. A expressão das enzimas guanilato ciclase solúvel e PDE5 foram menores em HG comparadas a HD, mas nenhuma diferença foi observada nos níveis de GMPc entre os dois grupos. Entretanto, níveis aumentados de GMPc foram observados em HG comparado aos grupos normotensos e a agregação plaquetária permaneceu inalterada. Os resultados sugerem que a redução da pressão arterial para valores normais no final da gravidez em SHR pode estar relacionada ao aumento da produção de NO e das respostas vasodilatadoras induzidas por angiotensina II e angiotensina 1-7, assim como à redução da expressão de ECA e receptores AT1 e do estado oxidativo no LAM. Além disso, este estudo revela a presença da via L-arginina-NO-GMPc em plaquetas de ratos. Apesar de uma reduzida biodisponibilidade plaquetária de NO, a agregação plaquetária permanece inalterada em HG, o que pode estar relacionado ao aumento dos níveis de GMPc e à reduzida expressão de PDE5. / During pregnancy the systemic maternal circulation adapts to facilitate uteroplacental perfusion and the renin-angiotensin system (RAS) plays an important role in this adaptation. The objective of this study was to investigate the contribution of RAS on the maternal cardiovascular regulation at the end of pregnancy as well as the L-arginine-NO-cGMP pathway in platelets from normotensive and spontaneously hypertensive rats (SHR). Mesenteric arterial bed (MAB) and platelets were obtained in the 20th day of pregnancy from female SHR (SHR-P) and normotensive controls (P) or age-matched non-pregnant rats (SHRNP and NP). The systolic blood pressure in P and SHR-P rats was reduced at the end of pregnancy. The vasodilator effects of angiotensin II and angiotensin 1-7, evaluated in norepinephrine preconstricted MAB, were higher in SHR-P than in other groups. Endothelial nitric oxide synthase (NOS) expression in MAB was evaluated by Western Blotting and was increased in P and SHR-P compared to their non-pregnant counterparts. Angiotensinconverting enzyme (ACE) and AT1 receptor expressions were increased in MAB from SHRNP compared to normotensive groups and the pregnancy reduced their expressions in SHR. On the other hand, ACE2 expression was higher in MAB from hypertensive than normotensive groups. Oxidative damage, evaluated by formation of thiobarbituric acid reaction substances (TBARS), was reduced in the pregnant groups compared to their nonpregnant counterparts. Superoxide dismutase activity was reduced in SHR-P compared to non-pregnant group. Pregnancy increased catalase activity in normotensive rats and increased glutathione peroxidase activity in SHR. In the platelet suspension, intraplatelet NOS activity measured by the conversion of L-[3H]-arginine to L-[3H]-citruline was reduced in P compared to NP, despite unchanged in L-arginine influx. The expressions of endothelial and inducible NOS, evaluated by Western Blotting, were decreased during pregnancy in normotensive rats. Paradoxically, cGMP levels were similar between NP and P, as well as phosphodiesterase5 (PDE5) expression and platelet aggregation induced by ADP. In SHR, L-arginine influx was reduced in SHR-P compared to SHR-NP. SHR-P had impaired NOS activity and reduced inducible NOS expression compared with SHR-NP. Soluble guanylate cyclase and PDE5 expressions were lower in SHR-P compared to SHR-NP while no differences were noted in cGMP levels between groups. However, increased levels of cGMP levels were observed in SHR-P compared to normotensive groups and platelet aggregability remained unaltered. The results suggest that the reduction of blood pressure to normal values at the end of pregnancy in SHR may be related to an increased NO production and vasorelaxation to Ang II and Ang 1-7 associated with decreased expression of vascular ACE and AT1 receptors and oxidative status. Morover, this study reveals the presence of L-arginine-NO-cGMP pathway in rat platelets. Despite reduced platelet NO bioavailability in pregnant hypertensive rats, platelet aggregability remains unaltered, which may be related to increased levels of cGMP and reduced expression of PDE5.