RESUMO
Abstract The regular practice of physical exercise as a non-pharmacological treatment of arterial hypertension (AH) has been encouraged due to causing a series of physiological responses in the cardiovascular system, such as the production of vasoactive substances, including nitric oxide (NO). NO is a relaxation factor released by the endothelium, and the decrease in its bioavailability is related to coronary and arterial diseases, such as AH. This study aimed to perform an integrative literature review to elucidate the effect of physical training on NO levels in patients with AH and to establish a relationship between these levels and blood pressure (BP) control. A literature review was was performed by searching PubMed / MEDLINE, Lilacs, Scielo, Cinahl and Embase databases. The search string used was ("arterial hypertension" OR hypertension) AND (exercise OR "physical exercise" OR "aerobic exercise" OR "exercise training" or "physical activity") AND ("nitric oxide"). We included fully available controlled and uncontrolled clinical trials published in English and Portuguese languages in the last 10 years. The review consisted of 16 articles, of which 13 reported an increase in NO production after the physical training intervention, and three studies found no change. In addition, 15 studies observed a reduction in BP after the intervention. In conclusion, regular practice of physical exercises, advocating moderate intensity, can improve NO bioavailability in pre-hypertensive and hypertensive individuals, which seems to be one of the mechanisms responsible for BP reduction.
Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Adulto Jovem , Exercício Físico/fisiologia , Hipertensão/terapia , Óxido Nítrico/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Pressão Arterial/fisiologia , Condicionamento Físico Humano/fisiologia , Hipertensão/metabolismoRESUMO
OBJECTIVE: To characterize the calcium influx pathways implicated in the sustained elevation of endothelial intracellular calcium concentration, required for the synthesis and release of relaxing factors. METHODS: We evaluated the effect of the newly synthesized pyrazole derivatives, described as selective inhibitors for ORAI (BTP2/Pyr2 and Pyr6) and TRPC3 (Pyr3 and Pyr10) channels, upon endothelium- and extracellular calcium-dependent relaxations stimulated by acetylcholine and thapsigargin, in pre-constricted rat thoracic aortic rings. RESULTS: Acetylcholine and thapsigargin responses were completely reverted by Pyr2 and Pyr6 (1 to 3µM). Pyr3 (0.3 to 3µM) caused a rapid reversal of acetylcholine (6.2±0.08mg.s-1) and thapsigargin (3.9±0.25mg.s-1) relaxations, whereas the more selective TRPC3 blocker Pyr10 (1 to 3µM) had no effect. The recently described TRPC4/5 selective blocker, ML204 (1 to 3µM), reverted completely acetylcholine relaxations, but minimally thapsigargin induced ones. Noteworthy, relaxations elicited by GSK1016790A (TRPV4 agonist) were unaffected by pyrazole compounds or ML204. After Pyr2 and Pyr6 pre-incubation, acetylcholine and thapsigargin evoked transient relaxations similar in magnitude and kinetics to those observed in the absence of extracellular calcium. Sodium nitroprusside relaxations as well as phenylephrine-induced contractions (denuded aorta) were not affected by any of pyrazole compounds (1 to 3µM). CONCLUSION: These observations revealed a previously unrecognized complexity in rat aorta endothelial calcium influx pathways, which result in production and release of nitric oxide. Pharmacologically distinguishable pathways mediate acetylcholine (ORAI/TRPC other than TRPC3/TRPC4 calcium-permeable channels) and thapsigargin (TRPC4 not required) induced calcium influx.
Assuntos
Acetilcolina/farmacologia , Cálcio/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Óxido Nítrico/metabolismo , Tapsigargina/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Canais de Cálcio Ativados pela Liberação de Cálcio/metabolismo , Masculino , Ratos Wistar , Canais de Cátion TRPC/metabolismo , Canais de Cátion TRPV/efeitos dos fármacos , Canais de Cátion TRPV/metabolismo , Fatores de Tempo , Vasodilatadores/farmacologiaRESUMO
ABSTRACT Objective: To characterize the calcium influx pathways implicated in the sustained elevation of endothelial intracellular calcium concentration, required for the synthesis and release of relaxing factors. Methods: We evaluated the effect of the newly synthesized pyrazole derivatives, described as selective inhibitors for ORAI (BTP2/Pyr2 and Pyr6) and TRPC3 (Pyr3 and Pyr10) channels, upon endothelium- and extracellular calcium-dependent relaxations stimulated by acetylcholine and thapsigargin, in pre-constricted rat thoracic aortic rings. Results: Acetylcholine and thapsigargin responses were completely reverted by Pyr2 and Pyr6 (1 to 3μM). Pyr3 (0.3 to 3μM) caused a rapid reversal of acetylcholine (6.2±0.08mg.s−1) and thapsigargin (3.9±0.25mg.s−1) relaxations, whereas the more selective TRPC3 blocker Pyr10 (1 to 3μM) had no effect. The recently described TRPC4/5 selective blocker, ML204 (1 to 3μM), reverted completely acetylcholine relaxations, but minimally thapsigargin induced ones. Noteworthy, relaxations elicited by GSK1016790A (TRPV4 agonist) were unaffected by pyrazole compounds or ML204. After Pyr2 and Pyr6 pre-incubation, acetylcholine and thapsigargin evoked transient relaxations similar in magnitude and kinetics to those observed in the absence of extracellular calcium. Sodium nitroprusside relaxations as well as phenylephrine-induced contractions (denuded aorta) were not affected by any of pyrazole compounds (1 to 3μM). Conclusion: These observations revealed a previously unrecognized complexity in rat aorta endothelial calcium influx pathways, which result in production and release of nitric oxide. Pharmacologically distinguishable pathways mediate acetylcholine (ORAI/TRPC other than TRPC3/TRPC4 calcium-permeable channels) and thapsigargin (TRPC4 not required) induced calcium influx.
RESUMO Objetivo: Caracterizar as vias do influxo de cálcio envolvidas no aumento sustentado da concentração intracelular de cálcio na célula endotelial, essencial para a síntese e a liberação de fatores relaxantes. Métodos: Analisamos o efeito de derivados pirazólicos sintetizados recentemente, descritos como inibidores seletivos para canais ORAI (BTP2/Pyr2 e Pyr6) e TRPC3 (Pyr3 e Pyr10), nos relaxamentos dependentes de endotélio e cálcio extracelular, produzidos por acetilcolina e tapsigargina, em anéis pré-contraídos da aorta torácica de rato. Resultados: As respostas de acetilcolina e tapsigargina foram completamente revertidas por Pyr2 e Pyr6 (1 a 3μM). Pyr3 (0,3 a 3μM) produziu reversão rápida dos relaxamentos de acetilcolina (6,2±0,08mg.s−1) e tapsigargina (3,9±0,25mg.s−1), enquanto o bloqueador mais seletivo para TRPC3, Pyr10 (1 a 3μM), não apresentou efeito. ML204 (1 a 3μM), bloqueador seletivo de TRPC4, descrito há pouco tempo, reverteu os relaxamentos induzidos por acetilcolina de forma completa, mas afetou minimamente aqueles produzidos por tapsigargina. Os derivados pirazólicos ou ML204 não afetaram os relaxamentos estimulados com GSK1016790A (TRPV4-agonista). Ainda, após pré-incubação com Pyr2 e Pyr6, acetilcolina e tapsigargina provocaram relaxamentos transitórios semelhantes em magnitude e cinética àqueles observados na ausência de cálcio extracelular. Os relaxamentos do nitroprussiato de sódio e as contrações induzidas pela fenilefrina (aorta sem endotélio) não foram afetados pelos compostos pirazólicos (1 a 3μM). Conclusão: Essas observações revelaram uma complexidade desconhecida das vias de influxo de cálcio no endotélio da aorta de rato, que resultam na produção e na liberação de óxido nítrico. Vias distinguíveis farmacologicamente medeiam o influxo estimulado por acetilcolina (ORAI TRPC, diferentes de TRPC3 TRPC4) e tapsigargina (TRPC4 não requerido).
Assuntos
Animais , Masculino , Acetilcolina/farmacologia , Cálcio/farmacologia , Tapsigargina/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Óxido Nítrico/metabolismo , Aorta Torácica/efeitos dos fármacos , Fatores de Tempo , Vasodilatadores/farmacologia , Ratos Wistar , Canais de Cátion TRPC/metabolismo , Canais de Cátion TRPV/efeitos dos fármacos , Canais de Cátion TRPV/metabolismo , Canais de Cálcio Ativados pela Liberação de Cálcio/metabolismoRESUMO
PURPOSE: To create in vitro a model to generate acidosis by CO2 bubbling "organ chambers", which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity. METHODS: Eighteen male Wistar rats (230-280 g) were housed, before the experiments, under standard laboratory conditions (12h light/dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO2) and pure CO2. RESULTS: 1) 100% CO2, pH variation very fast, pH minimum 6.0; 2) 90%CO2 pH variation bit slower, pH minimum 6.31; 3) 70%CO2, pH variation slower, pH minimum 6.32; 4) 50% CO2, pH variation slower, pH minimum 6:42; 5) 40 %CO2, Adequate record, pH minimum 6.61, and; 6) 30 %CO2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO2 40%) was adopted. CONCLUSION: This gas mixture (O2 60% + CO2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force.
Assuntos
Acidose Respiratória/induzido quimicamente , Dióxido de Carbono/metabolismo , Modelos Animais de Doenças , Endotélio Vascular/metabolismo , Acidose Respiratória/metabolismo , Acidose Respiratória/fisiopatologia , Animais , Gasometria , Dióxido de Carbono/química , Endotélio Vascular/química , Endotélio Vascular/fisiopatologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Masculino , Ratos Wistar , Valores de Referência , Reprodutibilidade dos TestesRESUMO
PURPOSE: To create in vitro a model to generate acidosis by CO2 bubbling "organ chambers", which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity. METHODS: Eighteen male Wistar rats (230-280g) were housed, before the experiments, under standard laboratory conditions (12h light/dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO2) and pure CO2. RESULTS: 1) 100% CO2, pH variation very fast, pH minimum 6.0; 2) 90%CO2 pH variation bit slower, pH minimum6.31; 3) 70%CO2, pH variation slower, pH minimum 6.32; 4) 50% CO2, pH variation slower, pH minimum 6:42; 5) 40 %CO2, Adequate record, pH minimum 6.61, and; 6) 30 %CO2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO2 40%) was adopted, CONCLUSION: This gas mixture (O2 60% + CO2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force. .
Assuntos
Animais , Masculino , Acidose Respiratória/induzido quimicamente , Dióxido de Carbono/metabolismo , Modelos Animais de Doenças , Endotélio Vascular/metabolismo , Acidose Respiratória/metabolismo , Acidose Respiratória/fisiopatologia , Gasometria , Dióxido de Carbono/química , Endotélio Vascular/química , Endotélio Vascular/fisiopatologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Ratos Wistar , Valores de Referência , Reprodutibilidade dos TestesRESUMO
OBJECTIVE: To investigate, in male Wistar rats, the effects of long-term moderate red wine (RW) consumption (equivalent to â¼0.15 mg% resveratrol RS), or RS in low (L, 0.15 mg%) or high (H, 400 mg%) doses in chow. BACKGROUND: Both RW and RS exhibit cardioprotection. RS extends lifespan in obese rats. It is unclear whether RW consumption or low-dose RS delay vascular aging and prolong life span in the absence of overt risk factors. METHODS: Endpoints were aerobic performance, exercise capacity, aging biomarkers (p53,p16,p21, telomere length and telomerase activity in aortic homogenates), vascular reactivity. Data were compared with controls (C) given regular chow. RESULTS: Expressions of p53 decreased â¼50% â¼with RW and LRS (p < 0.05 vs. C), p16 by â¼29% with RW (p < 0.05 vs. C) and p21 was unaltered. RW and LRS increased telomere length >6.5-fold vs. C, and telomerase activity increased with LRS and HRS. All treatments increased aerobic capacity (C 32.5 ± 1.2, RW 38.7 ± 1.7, LRS 38.5 ± 1.6, HRS 38.3 ± 1.8 mlO(2) min(-1) kg(-1)), and RW or LRS also improved time of exercise tolerance vs. C (p < 0.05). Endothelium-dependent relaxation improved with all treatments vs. C. Life span, however, was unaltered with each treatment vs. C = 673 ± 30 days, p = NS. CONCLUSIONS: RW and LRS can preserve vascular function indexes in normal rats, although not extending life span. These effects were translated into better aerobic performance and exercise capacity.
Assuntos
Envelhecimento/efeitos dos fármacos , Longevidade/efeitos dos fármacos , Estilbenos/administração & dosagem , Animais , Aorta/metabolismo , Vasos Sanguíneos/fisiologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Teste de Esforço , Masculino , Ratos , Ratos Wistar , Resveratrol , Telômero/metabolismo , Proteína Supressora de Tumor p53/metabolismo , VinhoRESUMO
BACKGROUND: The majority of studies have investigated the effect of exercise training (TR) on vascular responses in diabetic animals (DB), but none evaluated nitric oxide (NO) and advanced glycation end products (AGEs) formation associated with oxidant and antioxidant activities in femoral and coronary arteries from trained diabetic rats. Our hypothesis was that 8-week TR would alter AGEs levels in type 1 diabetic rats ameliorating vascular responsiveness. METHODOLOGY/PRINCIPAL FINDINGS: Male Wistar rats were divided into control sedentary (C/SD), sedentary diabetic (SD/DB), and trained diabetic (TR/DB). DB was induced by streptozotocin (i.p.: 60 mg/kg). TR was performed for 60 min per day, 5 days/week, during 8 weeks. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), phenylephrine (PHE) and tromboxane analog (U46619) were obtained. The protein expressions of eNOS, receptor for AGEs (RAGE), Cu/Zn-SOD and Mn-SOD were analyzed. Tissues NO production and reactive oxygen species (ROS) generation were evaluated. Plasma nitrate/nitrite (NO(x)â»), superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive substances (TBARS) and N(ε)-(carboxymethyl) lysine (CML, AGE biomarker). A rightward shift in the concentration-response curves to ACh was observed in femoral and coronary arteries from SD/DB that was accompanied by an increase in TBARS and CML levels. Decreased in the eNOS expression, tissues NO production and NO(x)â» levels were associated with increased ROS generation. A positive interaction between the beneficial effect of TR on the relaxing responses to ACh and the reduction in TBARS and CML levels were observed without changing in antioxidant activities. The eNOS protein expression, tissues NO production and ROS generation were fully re-established in TR/DB, but plasma NO(x)â» levels were partially restored. CONCLUSION: Shear stress induced by TR fully restores the eNOS/NO pathway in both preparations from non-treated diabetic rats, however, a massive production of AGEs still affecting relaxing responses possibly involving other endothelium-dependent vasodilator agents, mainly in coronary artery.
Assuntos
Vasos Coronários , Diabetes Mellitus Experimental , Endotélio Vascular/fisiopatologia , Artéria Femoral , Produtos Finais de Glicação Avançada/metabolismo , Condicionamento Físico Animal , Animais , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/metabolismo , Vasos Coronários/fisiopatologia , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Experimental/terapia , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Fatores Relaxantes Dependentes do Endotélio/farmacologia , Artéria Femoral/efeitos dos fármacos , Artéria Femoral/metabolismo , Artéria Femoral/fisiopatologia , Produtos Finais de Glicação Avançada/farmacologia , Masculino , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Espécies Reativas de Oxigênio/farmacologia , EstreptozocinaRESUMO
Nitric oxide (NO), primarily identified as an endothelium-derived relaxing factor, is a free radical that signals different biological processes. The identification of NO synthase (NOS) isoforms and the subsequent characterization of the mechanisms of cell activation of the enzymes permitted the partial understanding of both the physiological interactions and of the mechanisms of the diseases in which NO is involved. Mainly expressed in the vascular endothelium, the endothelial NOS isoform (eNOS) plays an important role in the regulation of vascular reactivity and in the development and progression of atherosclerosis. The purpose of this review is to contextualize the reader about the eNOS structure and its mechanisms of cell activation. In view of the advances in molecular biology, we will also address the known mechanisms of gene expression regulation and the role of variants on the genetic code of eNOS associated with cardiovascular phenotypes. Although the importance of NO as an atheroprotective molecule is recognized, our focus will be the review of the literature on NO and its participation in the modulation of the muscle vasodilatation phenotype.
Assuntos
Doenças Cardiovasculares/fisiopatologia , Endotélio Vascular/fisiopatologia , Óxido Nítrico Sintase Tipo III/fisiologia , Óxido Nítrico Sintase/fisiologia , Óxido Nítrico/fisiologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Ativação Enzimática , Regulação Enzimológica da Expressão Gênica/fisiologia , Humanos , Músculos/irrigação sanguínea , Óxido Nítrico/genética , Óxido Nítrico Sintase Tipo III/genética , Fenótipo , Vasoconstrição/fisiologia , Vasodilatação/fisiologiaRESUMO
O óxido nítrico (NO), primariamente identificado como um fator relaxante derivado do endotélio, é um radical livre atuante na sinalização de diferentes processos biológicos. A identificação das isoformas das sintases do NO (NOS) e a subsequente caracterização dos mecanismos de ativação celulares das enzimas possibilitaram tanto a compreensão de parte das interações fisiológicas como a compreensão de parte dos mecanismos de doença, na qual o NO está envolvido. A isoforma endotelial da NOS (eNOS), expressa principalmente no endotélio vascular, desempenha importante papel na regulação da reatividade vascular e no desenvolvimento e na progressão da aterosclerose. Esta revisão tem o propósito de contextualizar o leitor sobre a estrutura da eNOS e seus mecanismos de ativação celular. Tendo em vista os avanços da biologia molecular, trataremos ainda dos conhecidos mecanismos de regulação da expressão gênica e do papel de variantes no código genético da eNOS associados a fenótipos cardiovasculares. Embora se reconheça a importância do NO como molécula ateroprotetora, nossa atenção estará voltada à revisão de literatura envolvendo NO e sua participação na modulação do fenótipo de vasodilatação muscular.
Nitric oxide (NO), primarily identified as an endothelium-derived relaxing factor, is a free radical that signals different biological processes. The identification of NO synthase (NOS) isoforms and the subsequent characterization of the mechanisms of cell activation of the enzymes permitted the partial understanding of both the physiological interactions and of the mechanisms of the diseases in which NO is involved. Mainly expressed in the vascular endothelium, the endothelial NOS isoform (eNOS) plays an important role in the regulation of vascular reactivity and in the development and progression of atherosclerosis. The purpose of this review is to contextualize the reader about the eNOS structure and its mechanisms of cell activation. In view of the advances in molecular biology, we will also address the known mechanisms of gene expression regulation and the role of variants on the genetic code of eNOS associated with cardiovascular phenotypes. Although the importance of NO as an atheroprotective molecule is recognized, our focus will be the review of the literature on NO and its participation in the modulation of the muscle vasodilatation phenotype.
El óxido nítrico (NO), primariamente identificado como un factor relajante derivado del endotelio, es un radical libre actuante en la señalización de diferentes procesos biológicos. La identificación de las isoformas de las sintasas del NO (NOS) y la subsecuente caracterización de los mecanismos de activación celulares de las enzimas posibilitaron tanto la comprensión de parte de las interacciones fisiológicas como la comprensión de parte de los mecanismos de enfermedad, en la cual el NO está envuelto. La isoforma endotelial de la NOS (eNOS), expresada principalmente en el endotelio vascular, desempeña importante papel en la regulación de la reactividad vascular y en el desarrollo y en la progresión de la aterosclerosis. Esta revisión tiene el propósito de contextualizar al lector sobre la estructura de la eNOS y sus mecanismos de activación celular. Teniendo en vista los avances de la biología molecular, trataremos aun de los conocidos mecanismos de regulación de la expresión génica y del papel de variantes en el código genético de la eNOS asociados a fenotipos cardiovasculares. Aunque se reconozca la importancia del NO como molécula ateroprotectora, nuestra atención estará volcada a la revisión de literatura envolviendo NO y su participación en la modulación del fenotipo de vasodilatación muscular.
Assuntos
Humanos , Doenças Cardiovasculares/fisiopatologia , Endotélio Vascular/fisiopatologia , Óxido Nítrico Sintase Tipo III/fisiologia , Óxido Nítrico Sintase/fisiologia , Óxido Nítrico/fisiologia , Ativação Enzimática , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Músculos/irrigação sanguínea , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico/genética , Fenótipo , Vasoconstrição/fisiologia , Vasodilatação/fisiologiaRESUMO
OBJECTIVE: The aim of this study was to assess the release of endothelium-derived relaxing factors from the endocardium of canine atrial appendage. METHODS: To study the release of endothelium-derived relaxing factor (EDRF) from intact atrial endocardial endothelium, tube-shaped sutures of canine atrial appendages were performed and effluents from these tubes were bioassayed (isolated perfused organ chamber system) for detection of EDRF in canine coronary artery. RESULTS: Effluent from the right atrial appendage caused a relaxation of 58.4 +/- 10.1% and the left atrial appendage 74.9 +/- 8.5% from the initial prostagladin F2alpha contraction in coronary artery. No significant statistical difference was detected in effluent from the right and left atrial appendages. This relaxation was abolished by treating the heart tubes with Triton X-100 and reduced by treatment with LNMMA, a competitive inhibitor of nitric oxide and with indomethacin, an inhibitor of the cyclo-oxygenase pathway, also indicating the release of vasodilatory prostanoids from the endocardial endothelium. CONCLUSION: This study showed for the first time, in vitro luminal release of EDRF and prostacyclin from the canine heart atrium. The ability of the endocardial endothelium to produce these factors could play an important role in preventing thrombus formation in the cardiac chambers.
Assuntos
6-Cetoprostaglandina F1 alfa/metabolismo , Bioensaio , Endocárdio/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Análise de Variância , Animais , Bioensaio/métodos , Vasos Coronários/efeitos dos fármacos , Inibidores de Ciclo-Oxigenase/farmacologia , Cães , Inibidores Enzimáticos/farmacologia , Feminino , Átrios do Coração/metabolismo , Indometacina/farmacologia , Masculino , Óxido Nítrico/metabolismo , ômega-N-Metilarginina/farmacologiaRESUMO
OBJETIVO: Estudar a liberação de fatores relaxantes derivados do endotélio (EDRF) pelo endocárdio de aurículas de corações caninos. MÉTODOS: Aurículas atriais caninas foram suturadas em forma de tubos e o efluente desses tubos foram submetidos a ensaios biológicos (sistema de perfusão isolada em câmaras de órgãos) utilizando artéria coronária canina, para a detecção de EDRFs. RESULTADOS: O efluente da aurícula direita promoveu relaxamento de 58,4 + 10,1 por cento e da aurícula esquerda 74,9 + 8,5 por cento da contração inicial obtida pela ação da prostagladina F2α em artéria coronária. Não houve diferença estatística no relaxamento da artéria coronária induzido pelos efluentes das aurículas direita e esquerda. O relaxamento induzido pelos efluentes das aurículas direita e esquerda foi abolido pelo tratamento das mesmas com Triton X-100. O tratamento das aurículas com L-NMMA, um inibidor competitivo da síntese de óxido nítrico, e com indometacina, um inibidor da via da ciclooxigenase, promoveu redução no relaxamento da artéria coronária induzido pelo efluente auricular, indicando que o endotélio endocárdico libera óxido nítrico e prostanóides. CONCLUSÕES: Esse estudo demonstra, pela primeira vez, a liberação luminal in vitro de EDRF e prostaciclina pelo átrio de coração canino. A habilidade do endotélio endocárdico em produzir esses fatores pode ter um papel importante na prevenção da formação de trombos nas câmaras cardíacas.
OBJECTIVE: The aim of this study was to assess the release of endothelium-derived relaxing factors from the endocardium of canine atrial appendage. METHODS: To study the release of endothelium-derived relaxing factor (EDRF) from intact atrial endocardial endothelium, tube-shaped sutures of canine atrial appendages were performed and effluents from these tubes were bioassayed (isolated perfused organ chamber system) for detection of EDRF in canine coronary artery. RESULTS: Effluent from the right atrial appendage caused a relaxation of 58.4 + 10.1 percent and the left atrial appendage 74.9 + 8.5 percent from the initial prostagladin F2α contraction in coronary artery. No significant statistical difference was detected in effluent from the right and left atrial appendages. This relaxation was abolished by treating the heart tubes with Triton X-100 and reduced by treatment with LNMMA, a competitive inhibitor of nitric oxide and with indomethacin, an inhibitor of the cyclo-oxygenase pathway, also indicating the release of vasodilatory prostanoids from the endocardial endothelium. CONCLUSION: This study showed for the first time, in vitro luminal release of EDRF and prostacyclin from the canine heart atrium. The ability of the endocardial endothelium to produce these factors could play an important role in preventing thrombus formation in the cardiac chambers.
Assuntos
Animais , Cães , Feminino , Masculino , /metabolismo , Bioensaio , Endocárdio/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Análise de Variância , Bioensaio/métodos , Vasos Coronários/efeitos dos fármacos , Inibidores de Ciclo-Oxigenase/farmacologia , Inibidores Enzimáticos/farmacologia , Átrios do Coração/metabolismo , Indometacina/farmacologia , Óxido Nítrico/metabolismo , ômega-N-Metilarginina/farmacologiaRESUMO
Endothelium-dependent vasorelaxation in large vessels is mainly attributed to Nomega-nitro-L-arginine methyl ester (L-NAME)-sensitive endothelial nitric oxide (NO) synthase (eNOS)-derived NO production. Endothelium-derived hyperpolarizing factor (EDHF) is the component of endothelium-dependent relaxations that resists full blockade of NO synthases (NOS) and cyclooxygenases. H2O2 has been proposed as an EDHF in resistance vessels. In this work we propose that in mice aorta neuronal (n)NOS-derived H2O2 accounts for a large proportion of endothelium-dependent ACh-induced relaxation. In mice aorta rings, ACh-induced relaxation was inhibited by L-NAME and Nomega-nitro-L-arginine (L-NNA), two nonselective inhibitors of NOS, and attenuated by selective inhibition of nNOS with L-ArgNO2-L-Dbu-NH2 2TFA (L-ArgNO2-L-Dbu) and 1-(2-trifluoromethylphehyl)imidazole (TRIM). The relaxation induced by ACh was associated with enhanced H2O2 production in endothelial cells that was prevented by the addition of L-NAME, L-NNA, L-ArgNO2-L-Dbu, TRIM, and removal of the endothelium. The addition of catalase, an enzyme that degrades H2O2, reduced ACh-dependent relaxation and abolished ACh-induced H2O2 production. RT-PCR experiments showed the presence of mRNA for eNOS and nNOS but not inducible NOS in mice aorta. The constitutive expression of nNOS was confirmed by Western blot analysis in endothelium-containing vessels but not in endothelium-denuded vessels. Immunohistochemistry data confirmed the localization of nNOS in the vascular endothelium. Antisense knockdown of nNOS decreased both ACh-dependent relaxation and ACh-induced H2O2 production. Antisense knockdown of eNOS decreased ACh-induced relaxation but not H2O2 production. Residual relaxation in eNOS knockdown mouse aorta was further inhibited by the selective inhibition of nNOS with L-ArgNO2-L-Dbu. In conclusion, these results show that nNOS is constitutively expressed in the endothelium of mouse aorta and that nNOS-derived H2O2 is a major endothelium-dependent relaxing factor. Hence, in the mouse aorta, the effects of nonselective NOS inhibitors cannot be solely ascribed to NO release and action without considering the coparticipation of H2O2 in mediating vasodilatation.
Assuntos
Aorta Torácica/enzimologia , Fatores Biológicos/metabolismo , Endotélio Vascular/enzimologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Peróxido de Hidrogênio/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Vasodilatação , Acetilcolina/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Catalase/metabolismo , Relação Dose-Resposta a Droga , Endotélio Vascular/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Hidrazinas/farmacologia , Imidazóis/farmacologia , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos C57BL , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/metabolismo , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico Sintase Tipo I/antagonistas & inibidores , Óxido Nítrico Sintase Tipo I/genética , Óxido Nítrico Sintase Tipo III/metabolismo , Nitroarginina/farmacologia , Nitroprussiato/farmacologia , Oligonucleotídeos Antissenso/metabolismo , RNA Mensageiro/metabolismo , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
The determinant of the diabetic nephropathy is hyperglycemia, but hypertension and other genetic factors are also involved. Glomerulus is the focus of the injury, where mesangial cell proliferation and extracellular matrix occur because of the increase of the intra- and extracellular glucose concentration and overexpression of GLUT1. Sequentially, there are increases in the flow by the poliol pathway, oxidative stress, increased intracellular production of advanced glycation end products (AGEs), activation of the PKC pathway, increase of the activity of the hexosamine pathway, and activation of TGF-beta1. High glucose concentrations also increase angiotensin II (AII) levels. Therefore, glucose and AII exert similar effects in inducing extracellular matrix formation in the mesangial cells, using similar transductional signal, which increases TGF-beta1 levels. In this review we focus in the effect of glucose and AII in the mesangial cells in causing the events related to the genesis of diabetic nephropathy. The alterations in the signal pathways discussed in this review give support to the observational studies and clinical assays, where metabolic and antihypertensive controls obtained with angiotensin-converting inhibitors have shown important and additive effect in the prevention of the beginning and progression of diabetic nephropathy. New therapeutic strategies directed to the described intracellular events may give future additional benefits.
Assuntos
Nefropatias Diabéticas/etiologia , Mesângio Glomerular , Hiperglicemia/complicações , Angiotensina II/metabolismo , Proliferação de Células/efeitos dos fármacos , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/fisiopatologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Matriz Extracelular/efeitos dos fármacos , Matriz Extracelular/metabolismo , Mesângio Glomerular/metabolismo , Mesângio Glomerular/patologia , Mesângio Glomerular/fisiopatologia , Transportador de Glucose Tipo 1/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Humanos , Hiperglicemia/metabolismo , Hiperglicemia/fisiopatologia , Óxido Nítrico/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Sistema Renina-Angiotensina/efeitos dos fármacos , Esclerose/metabolismo , Esclerose/fisiopatologia , Fator de Crescimento Transformador beta1/metabolismo , Vasoconstritores/metabolismoRESUMO
O principal determinante da nefropatia diabética é a hiperglicemia, mas hipertensão e fatores genéticos também estão envolvidos. O glomérulo é o foco de lesão, onde proliferação celular mesangial e produção excessiva de matriz extracelular decorrem do aumento da glicose intracelular, por excesso de glicose extracelular e hiperexpressão de GLUT1. Seguem-se aumento do fluxo pela via dos polióis, estresse oxidativo intracelular, produção intracelular aumentada de produtos avançados da glicação não enzimática (AGEs), ativação da via da PKC, aumento da atividade da via das hexosaminas e ativação de TGF-beta1. Altas concentrações de glicose também aumentam angiotensina II (AII) nas células mesangiais por aumento intracelular da atividade da renina (ações intrácrinas, mediando efeitos proliferativos e inflamatórios diretamente). Portanto, glicose e AII exercem efeitos proliferativos celulares e de matriz extracelular nas células mesangiais, utilizando vias de transdução de sinais semelhantes, que levam a aumento de TGF-beta1. Nesse estudo são revisadas as vias que sinalizam os efeitos da glicose e AII nas células mesangiais em causar os eventos-chaves relacionados à gênese da glomerulopatia diabética. As alterações das vias de sinalização implicadas na glomerulopatia, aqui revisadas, suportam dados de estudos observacionais/ensaios clínicos, onde controle metabólico e anti-hipertensivo, especificamente com inibidores do sistema renina-angiotensina, têm-se mostrado importantes - e aditivos - na prevenção do início e progressão da nefropatia. Novas estratégias terapêuticas dirigidas aos eventos intracelulares descritos deverão futuramente promover benefício adicional.
The determinant of the diabetic nephropathy is hyperglycemia, but hypertension and other genetic factors are also involved. Glomerulus is the focus of the injury, where mesangial cell proliferation and extracellular matrix occur because of the increase of the intra- and extracellular glucose concentration and overexpression of GLUT1. Sequentially, there are increases in the flow by the poliol pathway, oxidative stress, increased intracellular production of advanced glycation end products (AGEs), activation of the PKC pathway, increase of the activity of the hexosamine pathway, and activation of TGF-beta1. High glucose concentrations also increase angiotensin II (AII) levels. Therefore, glucose and AII exert similar effects in inducing extracellular matrix formation in the mesangial cells, using similar transductional signal, which increases TGF-beta1 levels. In this review we focus in the effect of glucose and AII in the mesangial cells in causing the events related to the genesis of diabetic nephropathy. The alterations in the signal pathways discussed in this review give support to the observational studies and clinical assays, where metabolic and antihypertensive controls obtained with angiotensin-converting inhibitors have shown important and additive effect in the prevention of the beginning and progression of diabetic nephropathy. New therapeutic strategies directed to the described intracellular events may give future additional benefits.
Assuntos
Humanos , Nefropatias Diabéticas/etiologia , Mesângio Glomerular , Hiperglicemia/complicações , Angiotensina II/metabolismo , Proliferação de Células/efeitos dos fármacos , Nefropatias Diabéticas/metabolismo , Nefropatias Diabéticas/fisiopatologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Matriz Extracelular/efeitos dos fármacos , Matriz Extracelular/metabolismo , Mesângio Glomerular/metabolismo , Mesângio Glomerular/patologia , Mesângio Glomerular/fisiopatologia , Transportador de Glucose Tipo 1/metabolismo , /metabolismo , Hiperglicemia/metabolismo , Hiperglicemia/fisiopatologia , Óxido Nítrico/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Sistema Renina-Angiotensina/efeitos dos fármacos , Esclerose/metabolismo , Esclerose/fisiopatologia , Fator de Crescimento Transformador beta1/metabolismo , Vasoconstritores/metabolismoRESUMO
Nitric oxide and prostacyclin are endogenous endothelium-derived vasodilators, but little information is available on their release during hypothermia. This study was carried out to test the hypothesis that endothelium may modulate vascular reactivity to decreased temperature changes. Segments of contracted (prostaglandin F(2alpha), 2x10(-6)M) canine coronary, femoral, and renal arteries, with and without endothelium, were in vitro ("organ chambers") exposed to progressive hypothermia (from 37 to 10 degrees C) in graded steps. The study is limited to physiological measurements of vascular tone, in the presence or absence of PGI(2) and/or NOS inhibitors, which show correlation with the relaxation. Hypothermia induced vasodilatation of vessels with intact endothelium, which became endothelium-independent below 20 degrees C. This vasodilatation began at 35 degrees C and, in the presence of indomethacin (2x10(-6)M), at 30 degrees C. Endothelium-dependent vasodilatation to hypothermia was blocked by L-NMMA or L-NOARG (10(-5)M), two competitive inhibitors of nitric oxide synthase (n=5 each, P<0.05). Oxyhemoglobin (2x10(-6)M) also inhibited vasodilatation induced by hypothermia (n=6, P<0.05). Pretreatment with either atropine or pirenzepine (10(-6)M) inhibited hypothermia-mediated vasodilatation (n=5 each, P<0.05). The present in vitro study concluded that the endothelium is sensitive to temperature variations and indicated that PGI(2) and NO-dependent pathways may be involved endothelium-dependent relaxation to hypothermia. The endothelium-dependent vasodilatation to hypothermia, in systemic and coronary arteries, is mediated by the M1 muscarinic receptor.
Assuntos
Endotélio Vascular/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Epoprostenol/metabolismo , Hipotermia Induzida , Óxido Nítrico/metabolismo , Animais , Cães , Técnicas In Vitro , Indometacina/farmacologia , Artéria Renal/efeitos dos fármacos , Artéria Renal/fisiologia , TemperaturaRESUMO
Açai (Euterpe oleracea Mart.) a fruit from the Amazon region, largely consumed in Brazil is rich in polyphenols. Experiments were undertaken to determine whether hydro-alcoholic extract obtained from stone of açaí induces a vasodilator effect in the rat mesenteric vascular bed precontracted with norepinephrine (NE) and, if so, to elucidate the underlying mechanism. Açai stone extract (ASE, 0.3-100 microg) induced a long-lasting endothelium-dependent vasodilation that was significantly reduced by N(G)-nitro-l-arginine methyl ester (l-NAME) and (1)H-[1,2,3] oxadiazolo [4,4-a] quinoxalin-l-one (ODQ) and abolished by KCl (45 mM) plus l-NAME. In vessels precontrated with NE and KCl (45 mM) or treated with K(Ca)(+2) channel blockers (charybdotoxin plus apamin), the effect of ASE was significantly reduced. However this effect is not affect by indomethacin, glybenclamide and 4-aminopiridine. Atropine, pyrilamine, yohimbine and HOE 140 significantly reduced the vasodilator effect of acetylcholine, histamine, clonidine and bradykinin, respectively, but did not change the vasodilator effect of ASE. In cultured endothelial cells ASE (100 microg/mL) induced the formation of NO that was reduced by N(G)-nitro-l-arginine (l-NA, 100 microM). The present study demonstrates that the vasodilator effect of ASE is dependent on activation of NO-cGMP pathway and may also involve endothelium-derived hyperpolarizing factor (EDHF) release. The vasodilator effect suggest a possibility to use ASE as a medicinal plant, in the treatment of cardiovascular diseases.
Assuntos
Arecaceae , Endotélio Vascular/efeitos dos fármacos , Artérias Mesentéricas/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Animais , Arecaceae/química , Fatores Biológicos/metabolismo , Brasil , Células Cultivadas , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Células Endoteliais/efeitos dos fármacos , Endotélio Vascular/metabolismo , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Frutas , Guanilato Ciclase/metabolismo , Masculino , Mesentério/irrigação sanguínea , Óxido Nítrico/metabolismo , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Plantas Medicinais , Canais de Potássio/efeitos dos fármacos , Ratos , Ratos Wistar , Fatores de Tempo , Vasoconstritores/farmacologia , Vasodilatadores/isolamento & purificaçãoRESUMO
1. The mechanisms involved in the vasodilator actions of angiotensin II (Ang II) have not yet been completely elucidated. We investigated the potential mechanisms that seem to be involved in the Ang II vasodilator effect using rat isolated mesenteric vascular bed (MVB). 2. Under basal conditions, Ang II does not affect the perfusion pressure of MVB. However, in vessels precontracted with norepinephrine, Ang II induces vasodilation followed by vasoconstriction. Vasoconstrictor, but not the vasodilation of Ang II, is inhibited by AT(1) antagonist (losartan). The vasodilator effect of Ang II was not inhibited by AT(2), angiotensin IV and angiotensin 1-7 receptor antagonists alone (PD 123319, divalinal, A 779, respectively). 3. The vasodilator effect of Ang II is significantly reduced by endothelial removal (deoxycholic acid), but not by indomethacin. Inhibition of NO-synthase by N(G)-nitro-l-arginine methyl ester (l-NAME) and guanylyl cyclase by 1H-[1,2,3] oxadiazolo [4,4-a] quinoxalin-1-one (ODQ) reduces the vasodilator effect of Ang II. This effect is also reduced by tetraethylammonium (TEA) or l-NAME, and a combination of l-NAME plus TEA increases the inhibitory effect of the antagonists alone. However, indomethacin does not change the residual vasodilator effect observed in vessels pretreated with l-NAME plus TEA. 4. In vessels precontracted with norepinephrine and depolarized with KCl 25 mm or treated with Ca(2+)-dependent K(+) channel blockers (charybdotoxin plus apamin), the effect of Ang II was significantly reduced. However, this effect is not affected by ATP and voltage-dependent K(+) channel blockers (glybenclamide and 4-aminopyridine). 5. Inhibition of kininase II with captopril significantly potentiates the vasodilator effect of bradykinin (BK) and Ang II in the rat MVB. The inhibitory effect of the B(2) receptor antagonist HOE 140 on the vasodilator effect of Ang II is further enhanced by PD 123319 and/or A 779. 6. The present findings suggest that BK plays an important role in the endothelium-dependent vasodilator effect of Ang II. Probably, the link between Ang II and BK release is modulated by receptors that bind PD 123319 and A 779.
Assuntos
Angiotensina II/farmacologia , Angiotensina I/fisiologia , Bradicinina/fisiologia , Fatores Relaxantes Dependentes do Endotélio/metabolismo , Fragmentos de Peptídeos/fisiologia , Receptor Tipo 2 de Angiotensina/fisiologia , Vasodilatação/fisiologia , Animais , Técnicas In Vitro , Masculino , Artérias Mesentéricas/efeitos dos fármacos , Artérias Mesentéricas/fisiologia , Veias Mesentéricas/efeitos dos fármacos , Veias Mesentéricas/fisiologia , Ratos , Ratos Wistar , Receptores de Angiotensina/fisiologia , Vasodilatação/efeitos dos fármacosRESUMO
1. In this study, the role of endogenous H(2)O(2) as an endothelium-dependent relaxant factor was characterised in aortas from C57BL/6J and LDL receptor-deficient mice (LDLR(-/-)). 2. Aortic rings from LDLR(-/-) mice showed impaired endothelium-dependent relaxation to acetylcholine (ACh; 0.001-100 micro M) and to the Ca(2+) ionophore A23187 (0.001-3 micro M) compared with aortic rings from control mice. Endothelium-independent relaxation produced by the NO donor, 3-morpholino-sydnonimine (SIN-1) was not different between strains. 3. Pretreatment of vessels with L-NNA (100 micro M) or L-NNA (100 micro M) plus L-NAME (300 micro M) plus haemoglobin (10 micro M) markedly decreased, but did not abolish the relaxation to ACh in control mice. In the aortas from LDLR(-/-) mice treated with L-NNA (100 micro M), ACh induced a contractile effect. Catalase (800 and 2400 U ml(-1)) shifted to the right the endothelium-dependent relaxation to ACh in aortas from control but not from LDLR(-/-) mice. Aminotriazole (50 mM), which inhibits catalase, abolished its effect on control mice. Treatment of vessels with L-NNA and catalase abolished vasorelaxation induced by ACh. Indomethacin (10 micro M) did not modify the concentration-response curve to ACh. Superoxide dismutase (300 U ml(-1)) did not change ACh-induced relaxation in both strains. 4. Exogenous H(2)O(2) produced a concentration-dependent relaxation in endothelium-denuded aortic rings, which was not different between strains. 5. It is concluded that H(2)O(2) greatly contributes to relaxation to ACh in aorta from control mice. Endothelial-dependent relaxation to ACh is impaired in LDLR(-/-) mice. Reduced biosynthesis or increased inactivation of H(2)O(2) is the possible mechanism responsible for endothelial dysfunction in aortas of atherosclerosis-susceptible LDLR(-/-) mice.