A administração crônica de ouabaína (OUA) induz hipertensão arterial (HA) em ratos, alterações funcionais e remodelamento em artérias mesentéricas de resistência (AMR). A literatura sugere que a resposta pressórica da OUA pode ser bloqueada pelo antagonismo do receptor AT1 e pela inibição COX-2. No entanto, não se conhece a participação dessas vias no remodelamento arterial nesse modelo de HA. O presente estudo teve como objetivo investigar o papel do sistema renina-angiotensina (SRA) e da COX no remodelamento das AMR induzido pela OUA. Em AMR de ratos OUA, o SRA e a COX-2 participam da resposta pressórica, do remodelamento hipotrófico para dentro e da rigidez. Esses ajustes estão associados ao stress oxidativo e a deposição de colágeno na parede vascular estimulados pela capacidade da OUA em promover a ativação do receptor AT1 e da COX-2. / The chronic administration of ouabain (OUA) induces hypertension in rats, functional and structural alterations in mesenteric resistance arteries (MRA). It is well known that OUA-induced hypertension is blocked by AT1 receptor antagonism and the COX-2 inhibition. However, the participation of these pathways in MRA remodeling in this model of hypertension remains unknown. This study aimed to investigate the role of the renin angiotensin system (RAS) and COX pathways on MRA remodeling induced by OUA. In AMR from OUA rats, RAS and COX-2 participate in the pressor response, the inward hypotrophic remodeling and stiffness. These adjustments are the result of oxidative stressand increasing collagen deposition in the vascular wall stimulated by the OUA ability to stimulate the activation of AT1 receptor and COX-2.

Made available in DSpace on 2014-06-11T19:31:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2001Bitstream added on 2014-06-13T18:41:27Z : No. of bitstreams: 1 vailati_mcf_dr_botfm.pdf: 326485 bytes, checksum: 40ae6105076d1617c946e93f6158fd3d (MD5) / Um aspecto pouco explorado na literatura, é o caráter sistêmico das alterações vasculares induzidas pela angiotensina II (AII). Teoricamente, todos os tecidos podem ser afetados, visto que os receptores da AII já foram identificados em vários órgãos. Os trabalhos que avaliam o efeito da AII no miocárdio são concordantes no sentido de indicar lesões envolvendo vasos e tecido muscular. Não encontramos qualquer estudo que avaliasse o impacto dessas lesões na função ventricular, numa fase que precede a fibrose miocárdica. Foram utilizados 65 ratos Wistar, machos, com aproximadamente 250g de peso corpóreo, divididos em quatro grupos: controle (n=16), ratos tratados com AII (n= 17), ratos tratados com AII + carvedilol (90 mg/kg/dia; n = 15) e AII + losartan (30 mg/kg/dia; n = 17). A infusão contínua de AII foi realizada na dose de 150 hg/min, através de mini-bombas osmóticas colocadas no subcutâneo no dorso do animal. O registro das pressões arteriais caudais (PA) dos animais de cada grupo foi obtido, aproximadamente, 24h antes da implantação da minibomba e antes da realização da eutanásia. Foram realizados cortes histológicos de miocárdio, rim e fígado para coloração pela hematoxilina-eosina e observação das áreas de necrose. A intensidade das lesões foi definida por meio de escores. Uma parte dos animais foi destinada ao estudo histológico e a outra ao estudo do coração isolado. Também foi realizada a técnica de imunohistoquímica para identificação de macrófagos e a técnica vermelho-congo azul de toluidina para mastócitos e eosinófilos. A função ventricular foi avaliada no coração isolado (preparação de Langendorff). Os resultados foram comparados com os ratos do grupo controle, sem qualquer tratamento, por meio de ANOVA com nível de significância p<0,05... / The systemic aspect of vascular damage induced by angiotensin II (AII) is poorly explored in the literature. Considering the presence of AII in various organs, all these tissues might be affect by of AII. There is an agreement among the authors in relation to the effects of AII on the myocardium as involving vessels and myocytes. There is no published data regarding the impact of these lesions on ventricular function preceeding myocardial fibrosis. Sixty five male Wistar rats, (250 ± 20g) distributed in four groups were used: control (n=16), treated with AII (n=17), with AII + carvedilol (90 mg/kg/d, n=15) and AII+ losartan (30 mg/kg/d, n=17). AII was infused continuously at 150 hg/min (for 72 hs) by subcutaneous osmotic pumps. Tail cuff blood pressure was recorded 24 hours before the mini-pump implantation and before euthanasia. Histological sections of the myocardium, kidney and liver were stained by haematoxylin and eosin and observed for presence of necrosis. The injury intensity was scored. Immunohistochemistry was used for macrophages identification and congo red toluidine blue for identification of mast cells and eosinophils. The ventricular function was evaluated in the isolated heart (Langendorff preparation). The results were compared with untreated control rats, by ANOVA and the statistical significance was set at p<0,05. Blood pressure was higher in the groups AII and AII + carvedilol compared to control (165 ± 30 mmHg e 181± 35 mmHg vs 126 ± 13 mmHg, p<0,01). Losartan prevented hypertension. Histopathological analysis showed perivascular inflammation and necrosis of arteriolar wall in the myocardium, kidney, and liver. Carvedilol and losartan partially protected the organs. The intensity of tissular lesions was less than the vascular lesions, without statistical difference among the groups. There were macrophages and mast... (Complete abstract, click electronic address below)

Orientador: Beatriz Bojikian Matsubara / Resumo: Um aspecto pouco explorado na literatura, é o caráter sistêmico das alterações vasculares induzidas pela angiotensina II (AII). Teoricamente, todos os tecidos podem ser afetados, visto que os receptores da AII já foram identificados em vários órgãos. Os trabalhos que avaliam o efeito da AII no miocárdio são concordantes no sentido de indicar lesões envolvendo vasos e tecido muscular. Não encontramos qualquer estudo que avaliasse o impacto dessas lesões na função ventricular, numa fase que precede a fibrose miocárdica. Foram utilizados 65 ratos Wistar, machos, com aproximadamente 250g de peso corpóreo, divididos em quatro grupos: controle (n=16), ratos tratados com AII (n= 17), ratos tratados com AII + carvedilol (90 mg/kg/dia; n = 15) e AII + losartan (30 mg/kg/dia; n = 17). A infusão contínua de AII foi realizada na dose de 150 hg/min, através de mini-bombas osmóticas colocadas no subcutâneo no dorso do animal. O registro das pressões arteriais caudais (PA) dos animais de cada grupo foi obtido, aproximadamente, 24h antes da implantação da minibomba e antes da realização da eutanásia. Foram realizados cortes histológicos de miocárdio, rim e fígado para coloração pela hematoxilina-eosina e observação das áreas de necrose. A intensidade das lesões foi definida por meio de escores. Uma parte dos animais foi destinada ao estudo histológico e a outra ao estudo do coração isolado. Também foi realizada a técnica de imunohistoquímica para identificação de macrófagos e a técnica vermelho-congo azul de toluidina para mastócitos e eosinófilos. A função ventricular foi avaliada no coração isolado (preparação de Langendorff). Os resultados foram comparados com os ratos do grupo controle, sem qualquer tratamento, por meio de ANOVA com nível de significância p<0,05... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The systemic aspect of vascular damage induced by angiotensin II (AII) is poorly explored in the literature. Considering the presence of AII in various organs, all these tissues might be affect by of AII. There is an agreement among the authors in relation to the effects of AII on the myocardium as involving vessels and myocytes. There is no published data regarding the impact of these lesions on ventricular function preceeding myocardial fibrosis. Sixty five male Wistar rats, (250 ± 20g) distributed in four groups were used: control (n=16), treated with AII (n=17), with AII + carvedilol (90 mg/kg/d, n=15) and AII+ losartan (30 mg/kg/d, n=17). AII was infused continuously at 150 hg/min (for 72 hs) by subcutaneous osmotic pumps. Tail cuff blood pressure was recorded 24 hours before the mini-pump implantation and before euthanasia. Histological sections of the myocardium, kidney and liver were stained by haematoxylin and eosin and observed for presence of necrosis. The injury intensity was scored. Immunohistochemistry was used for macrophages identification and congo red toluidine blue for identification of mast cells and eosinophils. The ventricular function was evaluated in the isolated heart (Langendorff preparation). The results were compared with untreated control rats, by ANOVA and the statistical significance was set at p<0,05. Blood pressure was higher in the groups AII and AII + carvedilol compared to control (165 ± 30 mmHg e 181± 35 mmHg vs 126 ± 13 mmHg, p<0,01). Losartan prevented hypertension. Histopathological analysis showed perivascular inflammation and necrosis of arteriolar wall in the myocardium, kidney, and liver. Carvedilol and losartan partially protected the organs. The intensity of tissular lesions was less than the vascular lesions, without statistical difference among the groups. There were macrophages and mast... (Complete abstract, click electronic address below) / Doutor

Introdução: Nas últimas décadas os óbitos por DCNT aumentaram três vezes nos estados brasileiros. Assim, o objetivo do estudo foi identificar a prevalência da obesidade e da hipertensão arterial na população de crianças e adolescentes estudantes da rede estadual de ensino de Ribeirão Preto/SP. Métodos: Foi conduzido um estudo transversal com 505 crianças/adolescentes, da faixa etária de 10 a 16 anos, que frequentavam as escolas estaduais de Ribeirão Preto. A coleta de dados, foi realizada através de pesquisa de campo com visitas às escolas e entrevista dos alunos selecionados ao longo dos anos de 2013 e 2014. Medidas antropométricas (peso, altura, cintura, quadril), e os níveis de pressão arterial foram aferidos em todos os participantes. Resultados: Aproximadamente 53% (n=265) dos estudantes eram do gênero masculino e 47% (n=240) do gênero feminino, com média de idade de 12,74 anos. Verificou-se alteração do peso corporal em 30,9% da população estudada, sendo 18,22% com sobrepeso e 12,67% com obesidade, sem diferença estatística entre os gêneros. Quanto aos níveis de pressão arterial, verificou-se alteração em 8,71% da população total, sendo mais frequente no grupo feminino (4,95%). As crianças com níveis de PA normal admitem passar menos tempo livre sem gasto energético quando comparadas com as de PA alterada [RP 0,92 (IC95% 0,88 0,97)]. Encontrou-se associação significativa [RP 2,02 (IC95% 1,28;3,2)] para o IMC alterado e menarca antes dos 10 anos de idade. A análise de regressão linear simples mostrou associação positiva entre IMC e níveis de PA tanto sistólica (R² = 0,2244; y= 61,1770 + 1,8228x; p<0,001) quanto diastólica (R² = 0,3450; y = 35,2008 + 1,0726 x; p <0,0001). Para as demais variáveis comportamentais e de hábitos alimentares, não foram encontradas associações entre obesidade ou níveis de PA. Conclusão: Observou-se alta prevalência de obesidade e hipertensão arterial na população estudada. Foi encontrada associação positiva entre IMC e HAS. Para as variáveis comportamentais e alimentares poucas foram as associações. Houve associação para a ocorrência da menarca antes dos 10 anos e o IMC alterado. Houve associação também para o aumento dos níveis pressóricos e o tempo livre sem gasto energético. Não foram encontradas associações significativas entre consumo elevado de doces, refrigerantes e a prática de atividade física foi menor que a recomendação feita pela OMS. Ressalta-se a importância do desenvolvimento de estratégias de intervenção com a participação de equipe multiprofissional e familiares para prevenção e controle da obesidade e da hipertensão arterial nas crianças e adolescentes. / Introduction: In recent decades, deaths from CDNT increased three times in the Brazilian county. The objective of the study was to identify the prevalence of obesity and high blood pressure in the population of children and adolescents students of the county school of Ribeirão Preto/SP. Methods: A cross-sectional study was conducted with 505 children / adolescents, the age group 10-16 years who attended state schools in Ribeirão Preto/SP. Data collection was conducted through field research with visits to schools and interviews of selected students over the years 2013 and 2014. Anthropometric measurements (weight, height, waist, and hip) and blood pressure levels were measured for all participants. Results: Approximately 53% (n=265) of the students were male and 47 % (n 240) were female, with a mean age of 12.74 years. There was change in body weight in 30.9 % of the study population, and 18.22 % were overweight and 12.67 % were obese, with no statistical difference between genders. As for blood pressure levels, there was change to 8.71 % of the total population, being more frequent in the female group (4.95%). Children with normal BP levels admit spend less time off without energy expenditure compared with the amended BP [RP 0.92 (95% CI from 0.88 to 0.97)]. Found a significant association [RP 2.02(95% CI 1.28, 3.2)] BMI changed and menarche before 10 years of age. Simple linear regression analysis showed a positive association between BMI and both systolic BP levels (R² = 0.2244, y = 61.1770 + 1,8228x; p < 0.001) and diastolic (R² = 0.3450, y = 35 2008 x + 1.0726; p <0.0001). For the other behavioral and eating habits variables, there were no associations between obesity and BP levels. Conclusion: There was a high prevalence of obesity and hypertension in this population. There was a positive association between BMI and SAH. For behavioral and dietary variables were few associations. There was an association for the occurrence of menarche before age 10 and the changed BMI. Was associated also to increased blood pressure and the free time without energy expenditure. Significant associations between high consumption of sweets, soft drinks and physical activity lower than recommended were found. It emphasizes the importance of developing intervention strategies with the participation of multidisciplinary team, including schools and family for the prevention and control of obesity and high blood pressure in children and adolescents.

Pulmonary arterial hypertension (PAH) alters pulmonary hemodynamics by changing the vascular wall mechanics. Currently, pulmonary vascular resistance is used clinically to assess the disease. However, the invasive nature of pressure measurements, needed for calculating the resistance, prevents longitudinal monitoring of patients during therapy. This work employs wave reflection as an alternative measure of the downstream stiffness and proposes a new method for wave reflection assessment using only non-invasive phase contrast magnetic resonance (PCMR) flow data. The feasibility of the proposed method was investigated in a numerical model of blood flow in the right pulmonary artery. Furthermore, it was validated experimentally using a flow phantom and compared with an existing invasive technique. Finally, the feasibility of the method was tested in a study of the right pulmonary artery of a volunteer. This approach may provide a non-invasive method to evaluate PAH and its response to therapy.

Pulmonary arterial hypertension (PAH) alters pulmonary hemodynamics by changing the vascular wall mechanics. Currently, pulmonary vascular resistance is used clinically to assess the disease. However, the invasive nature of pressure measurements, needed for calculating the resistance, prevents longitudinal monitoring of patients during therapy. This work employs wave reflection as an alternative measure of the downstream stiffness and proposes a new method for wave reflection assessment using only non-invasive phase contrast magnetic resonance (PCMR) flow data. The feasibility of the proposed method was investigated in a numerical model of blood flow in the right pulmonary artery. Furthermore, it was validated experimentally using a flow phantom and compared with an existing invasive technique. Finally, the feasibility of the method was tested in a study of the right pulmonary artery of a volunteer. This approach may provide a non-invasive method to evaluate PAH and its response to therapy.

Systemic sclerosis (SSc; scleroderma) is a chronic multisystem autoimmune disease that includes prominent skin involvement in all patients and is characterized by fibrosis, inflammation, and microvascular injury of the skin and internal organs. Clinical trial design for patients with systemic sclerosis (SSc) has been confounded by the heterogeneity of disease progression and lack of objective outcome measures. This has hampered identification of therapies for patients who have frequently fatal fibrotic complications. Direct pulmonary complications are the leading cause of death in SSc. For clinical trials in patients with diffuse cutaneous SSc, identification of a pharmacodynamic biomarker associated with clinical improvement would allow for alternative approaches to trial design. Furthermore, identification of a diagnostic biomarker for SSc complicated by pulmonary arterial hypertension (SSc-PAH) would provide a reliable non-invasive method for diagnosis of pulmonary arterial hypertension. Through the combination of high throughput technologies and clinical information we have identified three preliminary biomarkers for SSc: i) Two pharmacodynamic biomarkers for diffuse skin disease (dcSSc), one in using mRNA from skin biopsies and one using proteomic profiles from sera; ii) a serum based proteomic classifier for the screening and diagnostic evaluation of pulmonary arterial hypertension in systemic sclerosis. We show these biomarkers can be applied to assess changes in skin disease in dSSc patients over time and with further development could be used to supplement or replace the physical examination assessment (Modified Rodnan Skin Score, MRSS) as an outcome measure in clinical trials for dcSSc patients. Routine use of these biomarkers in SSc clinical trial design could expand treatment options for a patient population that currently has few if any treatment options that slow progression of disease. Furthermore we identified a serum biomarker for the major SSc pulmonary complication, SSc-PAH. This diagnostic SSc-PAH biomarker has the potential to be used as a screening tool in order to reduce the need for unnecessary invasive diagnostic procedures. This non-invasive screening method could lead to early diagnosis thus improving patient survival and aid in clinical management of a complication for which there are several treatments but which is still frequently fatal. / 2018-06-15T00:00:00Z

Made available in DSpace on 2014-06-11T19:23:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-18Bitstream added on 2014-06-13T19:09:02Z : No. of bitstreams: 1 oliveirajr_sa_me_botfm.pdf: 1126092 bytes, checksum: 9767b89b53ffc12296fa5f7b701bc920 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tem sido demonstrado que a obesidade promove remodelação cardíaca em ratos. Este estudo investigou a influência da obesidade induzida por dieta hipercalórica (HP) sobre as variáveis nutricionais e o remodelamento cardíaco, considerando a hipertrofia, fibrose intersticial e composição de cadeias pesadas de miosina (MHC), em ratos normotensos Wistar Kyoto (WKY) e ratos espontaneamente hipertensos (SHR). Parcelas de SHR (20) e WKY (20) com 60 dias de idade foram distribuídas em quatro grupos: SHR-C, SHR-OB, WKY-C e WKY-OB. Os grupos C receberam uma dieta normocalórica (C, 3,15 Kcal/g) e os grupos OB foram tratados com uma dieta hipercalórica (4,5 Kcal/g) durante 20 semanas. Dois critérios foram adotados para refinar a composição dos grupos em referência à obesidade, baseados na ingestão alimentar e no peso corporal (PC). As determinações nutricionais incluíram ingestão calórica, eficiência alimentar, PC, adiposidade, glicemia e perfil lipidêmico. A pressão arterial sistólica (PAS) foi mensurada antes e após a intervenção dietética. As análises morfológicas abrangeram a pesagem dos átrios, ventrículos direito e esquerdo e o estudo da umidade procedeu-se em fragmentos cardíacos, hepáticos e pulmonares. Secções histológicas miocárdicas foram utilizadas para cálculo da área seccional do miócito (AM) e fração intersticial de colágeno (FIC). A composição relativa de MHCs foi determinada por eletroforese de gel de poliacrilamida duodecil sulfato de sódio. A composição dos grupos foi submetida à análise estatística pelo teste de proporções binomiais entre e dentro das populações. Algumas variáveis nutricionais e a PAS foram analisadas por MANOVA no modelo de medidas repetidas. Os demais dados foram avaliados por ANOVA e teste de Tukey. Uma interação vigente entre linhagem e tratamento foi notada na composição dos grupos. / Obesity has been shown to induce cardiac remodeling in rats. In this study, we investigated the influence of obesity induced by high-fat diet (HFD) on nutritional variables and cardiac remodeling, concerning hypertrophy, interstitial fibrosis and myosin heavy chain composition, in normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. Sixty-day-old SHR (n=20) and WKY (n=20) were distributed into four groups: SHR-C, SHR-OB, WKY-C e WKY-OB. The C groups received a control diet (C, 3,15 Kcal/g) and the OB groups were treated with a HFD (4,5 Kcal/g) during 20 weeks. Two criteria were adopted to refine the groups composition in reference to obesity based on food consumption and body weight (BW). Nutritional determinations included energy intake, feed efficiency, BW, adiposity, glycemia and lipid profile. Systolic blood pressure (SBP) was measured before and after diet intervention. Morphological analysis involved atria, right and left ventricles weights and humidity study was realized with cardiac, liver and lung pieces. Using myocardial histological sections, myocyte cross sectional areas (MA) and collagen interstitial fraction (CIF) were measured. Relative myosin heavy chain (MHC) composition was determined using sodium dodecyl sulfatepolyacrylamide gel electrophoresis. The groups compositions were submitted to statistical analysis by the binomial proportional test between and within populations. Some nutritional variables and SBP were analyzed by two-way MANOVA in repeated measures model. Other data were evaluated by two-way ANOVA and Tukey test. An interaction between strain and treatment was noted to groups composition. Alimentar efficiency was increased only in the WKYOB and glycemic tolerance was impaired in both OB groups. HFD induced an increase of BW (WKY-C 481.6±39.4 g; WKY-OB 611.4±48.2 g; p<0.05; SHRC 370.3±16.0 g; SHR-OB 410.8±9.3 g; p<0.05) and adiposity in both strains.

Orientador: Katashi Okoshi / Banca: Beatriz Bojikian Matsubara / Banca: Marcia Kiyomi Koike / Resumo: A hipertensão arterial sistêmica é uma das principais causas de insuficiência cardíada (IC). No processo do desenvolvimento da hipertrofia miocárdica e a evolução pra IC, decorrente da sobrecarga pressórica, a ativação dos sistemas nervoso simpático e renina-angiotensina-aldosterona exerce papel fundamental, e a aldosterona tem sido responsabilizada por muitos desses efeitos. Diversos estudos clínicos e experimentais mostraram que o bloqueio da aldosterona atenua a remodelação ventricular na IC avançada. Considerando os efeitos adversos da aldosterona, o bloqueio de seus receptores, na fase mais precoce ao desenvolvimento da IC, poderá ser também benéfico atenuando a progressão da remodelação cardíaca. Para investigar essa questão, foram utilizados ratos espontaneamente hipertensos, com 16 meses de idade, divididos em dois grupos experimentais: controle (CTL) e tratado com espironolactona 20 mg/kg/dia (ESP) por seis meses. A pressão arterial sistólica (PAS) foi medida no início e no final do experimento. A avaliação estrutural e funcional cardíaca in vivo foi realizada por ecocardiograma. O estudo funcional in vitro foi realizado pela técnica do músculo papilar do ventrículo esquerdo (VE). A reserva contrátil foi avaliada após o aumento da concentração de cálcio extracelular, contração pós-pausa e estimulação por β-agonista isoproterenol. Para análise estrutural in vitro foram medidos os pesos do VE, ventrículo direito, átrios, pulmão e amostra de fígado, e calculada a razão peso úmido/peso seco desses órgãos. Amostras do VE foram obtidas para análise histológica, com a finalidade de medira área seccional dos cardiomiócitos (hematoxilina e eosina) e a área ocupada pelo colágeno (picrosirius red), para quantificação de hidroxiprolina e realização da técnica do RT-PCR em tempo real... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Arterial hypertension is one of the main causes of heart failure (HF). In the process of myocardial hypertrophy and HF development due to pressure overload, activation of sympathetic nervous system and renin-angiotensin system plays a fundamental role. Several clinical and experimental studies have been shown that aldosterone blockade attenuates ventricular remodeling in advanced HF. Considering the aldosterone deleterious effects, we hypothesized that the blockade of its receptors in the early phase of HF development can attenuate the progression of cardiac remodeling. To investigate this issue, 16 month-old spontaneously hypertensive rats were used. Rats were separated into two groups: control (CTL) and spironolactone treated (SPR, 20 mg/kg/day) for six months. Systolic arterial pressure (SAP) was measured at the beginning and the end of the experiment. In vivo cardiac structural and functional evaluation was performed by echocardiogram. In vitro myocardial function was analyzed in left ventricular (LV) papillary muscles under isometric contractions. Contractiel reserve was evaluated after extracellular calcium concentration increase, post-pause contractions, and β-agonist isoproterenol stimulation. In vitro structural analysis was done bay measuring LV, right ventricle, and atria weight, and the wet-to-dry weight ratio of these organs and also lung and liver samples. LV samples were stored for histological analysis (cardiomyocyte cross-sectional area and myocardial collagen fraction), measurement of hydroxyproline concentration, and quantification of gene expression of proteins related to cardiac remodeling by real-time RT-PCR. According to sample distribution, normal or non-normal, Student's t test or Mann-Whitney test was used to compare the groups. Mortality rate was analyzed by log-rank test (Kaplan Meier curve). Statistical analysis... (Complete abstract click electronic access below) / Mestre

Orientador: Jose Antonio da Rocha Gontijo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciecias Medicas / Made available in DSpace on 2018-08-10T14:32:43Z (GMT). No. of bitstreams: 1 Menegon_LeonardoFantinato_D.pdf: 7692318 bytes, checksum: 10b59c22a031dbd309e7f75f1a357e43 (MD5) Previous issue date: 2007 / Resumo: Evidências recentes demonstram uma estreita correlação entre situações de resistência ao efeito hipoglicemiante da insulina e conseqüente hiperinsulinemia, e hipertensão arterial sistêmica. Especula-se que a insulina possa desempenhar um papel no desenvolvimento ou manutenção da hipertensão arterial. Embora autores demonstrem que a administração periférica de insulina diminui a excreção urinária de sódio, sugerindo uma atrativa ligação entre seu efeito renal e o desenvolvimento ou manutenção da hipertensão arterial, estudos de nosso laboratório indicam que a administração intracerebroventricular de insulina promove significativo aumento da excreção de sódio. É possível que a resistência central ao efeito natriurético da insulina promoveria um desequilíbrio na homeostase hidro-salina, favorecendo a retenção crônica de sódio. O presente estudo foi designado para avaliar o efeito da administração intracerebroventricular aguda de insulina sobre a excreção urinária de sódio em ratos WKy e SHR, assim como caracterizar a ação direta da insulina sobre as vias de sinalização intracelulares da insulina (PI 3-quinase e MAPK) no hipotálamo destes ratos. Ainda, avaliar se a administração intracerebroventricular crônica de insulina poderia alterar a resposta dos receptores de insulina, atenuando o efeito natriurético da insulina. Demonstramos que a administração crônica intracerebroventricular de insulina atenuou significativamente a resposta natriurética da insulina, porém não alterou a pressão arterial de ratos normotensos. A natriurese mediada pela insulina em sistema nervoso central é regulada pela via da MAPK-ERK-1/2. Ratos SHR não apresentam incrementos na fosforilação desta via e na excreção de sódio estimulada pela insulina, caracterizando estes animais como centralmente resistentes à ação natriurética da insulina. Um possível desequilíbrio entre a ação periférica e central da insulina sobre a regulação da natriurese nos ratos hipertensos poderia levar a alterações na homeostase hidro-salina, favorecendo a retenção crônica de sódio, contribuindo para o desenvolvimento e manutenção da hipertensão arterial / Abstract: Chronic elevated plasma insulin levels and resistance to the hypoglycemic effect of insulin have been associated with increased blood pressure in human and animal models of hypertension. This observation has led to the speculation that insulin may play a role in the development of increased blood pressure. Although authors have shown that the peripheral action of insulin reduces urinary sodium excretion, suggesting an attractive reciprocal link between insulin¿s renal effect, urinary sodium excretion and the development or maintenance of hypertension, studies from our laboratory have indicated that acute intracerebroventricular injection of insulin significantly increases the output of sodium. Thus, we hypothesized that central resistance to the natriuretic effect of intracerebroventricular administration of insulin could lead to an inability of renal tubules to handle the hydroelectrolyte balance. To test this hypothesis, we investigated the effects of acute intracerebroventricular insulin administration on sodium tubular handling in SHR and WKy, and characterized the direct actions of insulin on the PI 3-kinase and MAP-kinase in the hypothalamus of these rats. Furthermore, we investigated the long-term effect of intracerebroventricular administration of insulin on sodium tubular handling and arterial pressure of normotensive rats. We demonstrated that chronic intracerebroventricular insulin injection attenuated urinary sodium excretion. However, this altered response did not simultaneously change the arterial blood pressure at this time. We functionally characterized the MAPK-ERK-1/2 as the intracellular hypothalamic pathway responsible for insulin-mediated natriuresis in rats. On the other hand, our results show that central insulin administration is less effective in inducing activation of the MAPK pathway and natriuresis in SHR rats, characterizing these rats as centrally resistant to insulin-mediated natriuresis. Thus, central resistance to the natriuretic effect of insulin could lead to an inability of renal tubules to handle the hydroelectrolyte balance, possibly contributing to the development or maintenance of hypertension / Doutorado / Medicina Experimental / Doutor em Fisiopatologia Medica