RESUMO
Temporal consequences of neurocompensation to balloon injury on endothelinergic functionality in rat contralateral carotid were evaluated. Rats underwent balloon injury in left carotid and were treated with CP-96345 (NK1 antagonist). Concentration-response curves for endothelin-1 were obtained in contralateral (right) carotid at 2, 8, 16, 30, or 45 days after surgery in the absence or presence of BQ-123 (ETA antagonist), BQ-788 (ETB antagonist), or Tempol (superoxide-dismutase mimic). Endothelin-1-induced calcium mobilization was evaluated in functional assays carried out with BQ-123, BQ-788, or Tempol. Endothelin-1-induced NADPH oxidase-driven superoxide generation was measured by lucigenin chemiluminescence assays performed with BQ-123 or BQ-788. Endothelin-1-induced contraction was increased in contralateral carotid from the sixteenth day after surgery. This response was restored in CP-96345-treated rats. Endothelium removal or BQ-123 did not change endothelin-1-induced contraction in contralateral carotid. This response was restored by BQ-788 or Tempol. Contralateral carotid exhibited an increased endothelin-1-induced calcium mobilization, which was restored by BQ-788 or Tempol. Contralateral carotid exhibited an increased endothelin-1-induced lucigenin chemiluminescence, which was restored by BQ-788. We conclude that the NK1-mediated neurocompensatory response to balloon injury elicits a contractile hyperreactivity to endothelin-1 in rat contralateral carotid by enhancing the muscular ETB-mediated NADPH oxidase-driven generation of superoxide, which activates calcium channels.
Assuntos
Artérias Carótidas/fisiopatologia , Lesões das Artérias Carótidas/cirurgia , Endotelina-1/genética , Endotélio/efeitos dos fármacos , Contração Muscular/efeitos dos fármacos , Acridinas/química , Animais , Compostos de Bifenilo/administração & dosagem , Cálcio/metabolismo , Artérias Carótidas/cirurgia , Lesões das Artérias Carótidas/tratamento farmacológico , Lesões das Artérias Carótidas/fisiopatologia , Óxidos N-Cíclicos/administração & dosagem , Endotelina-1/antagonistas & inibidores , Endotélio/metabolismo , Endotélio/cirurgia , Masculino , Oligopeptídeos/administração & dosagem , Peptídeos Cíclicos/administração & dosagem , Piperidinas/administração & dosagem , Ratos , Receptor de Endotelina A/genética , Marcadores de Spin , Superóxidos/metabolismo , Vasoconstrição/efeitos dos fármacosRESUMO
OBJECTIVES: To investigate the mechanisms underlying the effects of chronic restraint stress on the vascular contractile response induced by angiotensin (Ang) II in rat carotid. METHODS: Concentration-response curves for AngII were obtained in endothelium-intact or endothelium-denuded carotid rings, in the absence or presence of SC-560 (COX-1 inhibitor), SC-236 (COX-2 inhibitor), wortmannin (PI3 K-Akt inhibitor), ML171 (NOX-1 inhibitor), VAS2870 (NOX-4 inhibitor), tiron (O2- scavenger) or PEG-catalase (H2 O2 scavenger). 6-ketoPGF1α , TXB2 , O2- or H2 O2 levels and superoxide dismutase and catalase activity or expression were also measured in rat carotid. KEY FINDINGS: Stress increased AngII potency in rat carotid. Muscular COX-1 or COX-2-derived metabolites negatively modulated AngII-induced contraction in control rat carotid. Endothelial COX-1 or COX-2-derived metabolites positively modulated AngII-induced contraction in stressed rat carotid. PI3 K-Akt, NOX-1, NOX-4, O2- and H2 O2 positively modulated AngII-induced contraction in stressed rat carotid. Stress increased 6-ketoPGF1α or H2 O2 generation and reduced catalase activity in rat carotid. Protein expression of COX-1, NOX-4 or p-Akt was increased in stressed rat carotid. CONCLUSIONS: Stress increases AngII potency in rat carotid by a mechanism that involves the increased generation of PGI2 and H2 O2 and the activation of Akt pathway. Such mechanism could play a pathophysiological role in cardiovascular diseases correlated with stress.
Assuntos
Angiotensina II/metabolismo , Artérias Carótidas/metabolismo , Prostaglandina-Endoperóxido Sintases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Restrição Física , Estresse Psicológico/metabolismo , Vasoconstrição , 6-Cetoprostaglandina F1 alfa/metabolismo , Animais , Catalase/metabolismo , Corticosterona/sangue , Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/metabolismo , Inibidores de Ciclo-Oxigenase , Endotélio Vascular/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Contração Muscular , Músculo Liso Vascular/fisiologia , NADPH Oxidase 4 , NADPH Oxidases/metabolismo , Oxidiazóis/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos Wistar , Estresse Psicológico/etiologia , Estresse Psicológico/fisiopatologiaRESUMO
OBJECTIVES: Our main objective was to investigate the mechanisms underlying the effects of hyperhomocysteinaemia (HHcy) on contractile response mediated by α1-adrenoceptors in the rat corpus cavernosum. METHODS: Concentration-response curves for phenylephrine (PE) were obtained in strips of corpus cavernosum, in absence or after incubation with tiron, tempol or polyethylene glycol (PEG)-catalase combined or not with tempol. We also measured the superoxide anion (O2(-)) and hydrogen peroxide (H2O2) generation, superoxide dismutase (SOD) and catalase activity and α-actin expression in rat corpus cavernosum from both groups. KEY FINDINGS: HHcy increased PE-induced contraction in cavernosal strips. Tiron, PEG-catalase or tempol increased PE-induced contraction in strips from control rats, but it was not altered by tiron or PEG-catalase in HHcy rats, whereas tempol reduced this response. The combination of PEG-catalase and tempol did not alter the contractile response to PE in both groups. HHcy increased O2(-) generation and SOD activity, whereas H2O2 concentration was reduced. Finally, HHcy did not alter catalase activity or expression of α-actin. CONCLUSIONS: The major new finding from this study is that HHcy induced a marked increase in PE-induced contraction in rat corpus cavernosum by a mechanism that involves increased O2(-) generation and it could play a role in the pathogenesis of erectile dysfunction associated with HHcy.
Assuntos
Hiper-Homocisteinemia/metabolismo , Pênis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Actinas/metabolismo , Animais , Catalase/metabolismo , Disfunção Erétil/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Músculo Liso/efeitos dos fármacos , Músculo Liso/metabolismo , Pênis/efeitos dos fármacos , Fenilefrina/farmacologia , Polietilenoglicóis/metabolismo , Ratos , Ratos Wistar , Superóxidos/metabolismoRESUMO
There are many evidences indicating a compensatory mechanism in contralateral carotids following balloon injury. Previously it was observed α1-adrenoceptor-mediated hyper-reactivity and impairment of calcium influx in contralateral carotids 4 days after injury. At a later stage, α1-adrenoceptor-mediated contraction is similar to the control and we hypothesized that downstream signaling was normal. In the present study, we aimed to evaluate α1-adrenoceptor-mediated calcium influx in contralateral carotids 15 days after balloon injury. Concentration-response curves for CaCl2 in presence of the α1-adrenoceptor agonist (phenylephrine), measurement of the intracellular calcium transient and the levels of reactive oxygen species using fluorescent dyes were performed in control and contralateral carotids. Phenylephrine-induced intracellular calcium mobilization in contralateral carotids was not altered, while phenylephrine-induced calcium influx was reduced in the contralateral artery. Nitric oxide synthase inhibitors, L-NAME or L-NNA, restored this response, but nitrite and nitrate levels were decreased in contralateral carotids. Additionally, a rise in oxygen free radicals was observed in contralateral carotids. Furthermore, Tiron, a superoxide anion scavenger, restored α1-adrenoceptor-mediated calcium influx in contralateral carotids to the control level. Similar results were observed with the selective potassium channels blockers 4-aminopyridine and charybdotoxin. In conclusion, data showed that balloon catheter injury resulted in increased superoxide anions levels, activation of potassium channels (Kv and BKCa), inhibition of calcium channels (Cav) and preservation of α1-adrenoceptor-mediated contraction at a later stage after injury.
Assuntos
Angioplastia Coronária com Balão/efeitos adversos , Cálcio/fisiologia , Artérias Carótidas/metabolismo , Lesões das Artérias Carótidas/metabolismo , Receptores Adrenérgicos alfa 1/fisiologia , Superóxidos/metabolismo , Sal Dissódico do Ácido 1,2-Di-Hidroxibenzeno-3,5 Dissulfônico/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Artérias Carótidas/fisiopatologia , Lesões das Artérias Carótidas/fisiopatologia , Sequestradores de Radicais Livres/farmacologia , Masculino , Nitratos/metabolismo , Nitritos/metabolismo , Ratos , Ratos Wistar , Verapamil/farmacologiaRESUMO
AIMS: We investigated the effects of chronic ethanol consumption on the cavernosal smooth muscle (CSM) reactivity to endothelin-1 (ET-1) and the expression of ET system components in this tissue. METHODS: Male Wistar rats were treated with heavy dose of ethanol (20% v/v) for 6 weeks. Reactivity experiments were performed in the isolated rat CSM. Plasma and CSM nitrate generation and also superoxide anion generation in rat CSM were measured by chemiluminescence. Protein and mRNA levels of pre-pro-ET-1, endothelin-converting enzyme-1 (ECE-1), ETA and ETB receptors, eNOS, nNOS and iNOS were assessed by western immunoblotting and quantitative real-time polymerase chain reaction, respectively. RESULTS: Chronic ethanol consumption increased plasma ET-1 levels and the contractile response induced by this peptide in the isolated CSM. The relaxation induced by acetylcholine, but not IRL1620, a selective ETB receptor agonist, was reduced in CSM from ethanol-treated rats. BQ123, a selective ETA receptor antagonist, produced a rightward displacement of the ET-1 concentration-response curves in CSM from control, but not ethanol-treated rats. Reduced levels of nitrate were found in the plasma and CSM from ethanol-treated rats. Ethanol consumption increased superoxide anion generation in the rat CSM. The mRNA levels of pre-pro-ET-1, ECE-1, ETA and ETB receptors, eNOS, nNOS and iNOS were not altered by ethanol consumption. Protein levels of ET-1, ETA receptor and iNOS were higher in the CSM from rats chronically treated with ethanol. CONCLUSION: The major findings of the present study are that heavy ethanol consumption increases plasma ET-1 levels and the contraction induced by the peptide in the CSM. Increased CSM reactivity to ET-1 and altered protein levels of ET-1 and ETA receptors could play a role in the pathogenesis of erectile dysfunction associated with chronic ethanol consumption.
Assuntos
Depressores do Sistema Nervoso Central/farmacologia , Endotelina-1/biossíntese , Etanol/farmacologia , Músculo Liso/metabolismo , Pênis/metabolismo , Animais , Ácido Aspártico Endopeptidases/biossíntese , Western Blotting , Peso Corporal/efeitos dos fármacos , Depressores do Sistema Nervoso Central/sangue , Endotelina-1/sangue , Enzimas Conversoras de Endotelina , Etanol/sangue , Luminescência , Masculino , Metaloendopeptidases/biossíntese , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Pênis/efeitos dos fármacos , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase em Tempo Real , Receptor de Endotelina A/biossíntese , Receptor de Endotelina B/biossíntese , Superóxidos/metabolismoRESUMO
The purpose from this study was to investigate the consequences of sensory neurocompensation to carotid balloon injury in diabetic rats on angiotensin II-induced contraction and basal blood flow in contralateral carotid. Concentration-response curves for angiotensin II and blood flow were obtained in contralateral carotid from non-treated or capsaicin-treated streptozotocin-induced diabetic rats that underwent carotid balloon injury. Diabetes increased angiotensin II-induced contraction and impaired the blood flow in non-operated rat carotid. In diabetic rats, balloon injury led to neointima formation, which reduced the blood flow in ipsilateral carotid. Carotid balloon injury in diabetic rats reduced angiotensin II-induced contraction and restored the blood flow in contralateral carotid when compared to diabetic non-operated rat carotid. Capsaicin inhibited the effects evoked by carotid balloon injury on diabetic rat contralateral carotid. Endothelium removal, PEG-catalase (hydrogen peroxide scavenger) or l-NPA (neuronal nitric oxide synthase, nNOS, inhibitor) increased angiotensin II-induced contraction in contralateral carotid from diabetic operated rats to the levels observed in diabetic non-operated rat carotid. Our findings suggest that carotid balloon injury in diabetic rats elicits a neurocompensation that attenuates the diabetic hyperreactivity to angiotensin II in contralateral carotid by a sensory nerves-dependent mechanism mediated by hydrogen peroxide derived from endothelial nNOS. This sensory mechanism also restored the blood flow in this vessel, compensating the impaired blood flow in diabetic rat ipsilateral carotid. Thus, our major conclusions are that Diabetes confers a vasoprotective significance to the neurocompensation to carotid balloon injury in preventing further damage at carotid cerebral irrigation after angioplasty in diabetic subjects.
Assuntos
Angioplastia com Balão/efeitos adversos , Lesões das Artérias Carótidas/fisiopatologia , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Tipo 1/fisiopatologia , Angiotensina II , Animais , Aorta/fisiopatologia , Lesões das Artérias Carótidas/metabolismo , Lesões das Artérias Carótidas/patologia , Circulação Cerebrovascular , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/patologia , Peróxido de Hidrogênio/metabolismo , Masculino , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Ratos , Ratos Wistar , Superóxidos/metabolismo , Vasoconstrição/fisiologiaRESUMO
AIMS: Wall shear stress differentially regulates the arginase pathway in carotid arteries perfused ex vivo. Specific patterns of wall shear stress can locally determine atherosclerotic plaque size and composition in vivo. The present work investigates the effects of arginase inhibition on shear stress induced plaque composition. METHODS AND RESULTS: Carotid arteries of apolipoprotein E deficient mice were exposed to high (HSS), low (LSS) and oscillatory (OSS) shear stress conditions by the placement of a local shear stress modifier device for 9 weeks with or without the administration of the arginase inhibitor N-ω-Hydroxy-nor-L-arginine (nor-Noha) (10 mg/kg, i.p., 5 days/week). Carotid arginase activity was measured by colorimetric determination of urea. Atherosclerotic plaque size and composition, arginase expression and cellular localization were assessed by immunohistochemistry. Arginase activity was significantly increased in both LSS and OSS regions as compared to HSS. In the lesions, arginase II isoform co-localized preferentially with EC. Inhibition of arginase by nor-Noha decreased arginase activity and reduced plaque size in both LSS and OSS regions. Arginase inhibition affected mainly the composition of plaques developed in LSS regions by decreasing the total vascular ROS, the number of macrophages, apoptosis rate, lipid and collagen contents. CONCLUSIONS: Arginase activity is modulated by patterns of wall shear stress in vivo. Chronic inhibition of vascular arginase decreased the size of atherosclerotic lesions in both OSS and LSS regions, whereas changes on plaque composition were more pronounced in plaques induced by LSS. We identified wall shear stress as a key biomechanical regulator of arginase during plaque formation and stability.
Assuntos
Apolipoproteínas E/genética , Arginase/antagonistas & inibidores , Artérias Carótidas/patologia , Placa Aterosclerótica/patologia , Animais , Apoptose , Arginase/metabolismo , Arginina/análogos & derivados , Arginina/farmacologia , Aterosclerose/metabolismo , Fenômenos Biomecânicos , Artérias Carótidas/enzimologia , Proliferação de Células , Colágeno/análise , Hemodinâmica , Lipídeos/análise , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Placa Aterosclerótica/enzimologia , Placa Aterosclerótica/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Resistência ao Cisalhamento , Estresse Mecânico , Fatores de TempoRESUMO
Plants have always been an exemplary source of drugs and many of the currently available medicines have been directly or indirectly derived from them. For this reason, the research, development and use of natural products as therapeutic agents, especially those derived from plants, have been increasing in recent years. A great deal of attention has focused on the naturally occurring antispasmodic phytochemicals as potential drugs for the treatment of cardiovascular diseases. Arterial hypertension is a common and progressive disorder that poses a major risk for cardiovascular and renal diseases. Recent data have revealed that the global burden of hypertension is an important and increasing public health problem worldwide and that the level of awareness, treatment and control of hypertension varies considerably among countries. The research on naturally occurring blood pressure-lowering agents is rapidly expanding due to the high potential of such molecules as new antihypertensive drugs. Recently, a great number of plant-derived substances, such as diterpenoids, have been evaluated as possible antihypertensive agents. Naturally occurring diterpenes such as forskolin and stevioside, exhibit vasorelaxant action and inhibit vascular contractility by different mechanisms of action. In this review we will discuss the mechanisms underlying the hypotensive action displayed by diterpenes and their potential use in human hypertension. We will also discuss the use of these compounds in the treatment of glaucoma, which is characterized by increased intraocular pressure (IOP).
Assuntos
Anti-Hipertensivos/uso terapêutico , Diterpenos/uso terapêutico , Hipertensão/tratamento farmacológico , Fitoterapia , Extratos Vegetais/uso terapêutico , Anti-Hipertensivos/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Diterpenos/farmacologia , Glaucoma/tratamento farmacológico , Humanos , Extratos Vegetais/farmacologiaRESUMO
Balloon catheter injury results in hyper-reactivity to phenylephrine in contralateral carotids. Decreased nitric oxide (NO) modulation and/or increased intracellular calcium concentration triggers vascular smooth muscle contraction. Therefore, this study explores the participation of NO signaling pathway and calcium mobilization on hyper-reactivity to phenylephrine in contralateral carotids. Concentration-response curves for calcium (CaCl(2)) and phenylephrine were obtained in control and contralateral carotids four days after balloon injury, in the presence and absence of the inhibitors (L-NAME, L-NNA, 1400W, 7-NI, Oxyhemoglobin, ODQ or Tiron). Confocal microscopy using Fluo-3AM or DHE was performed to detect the intracellular levels of calcium and reactive oxygen species, respectively. The modulation of NO on phenylephrine-induced contraction was absent in the contralateral carotid. Phenylephrine-induced intracellular calcium mobilization was not altered in contralateral carotids. However, extracellular calcium mobilization by phenylephrine was reduced in the contralateral carotid compared to control arteries, and this result was confirmed by confocal microscopy. L-NAME increased phenylephrine-induced extracellular calcium mobilization in the contralateral carotid to the control levels. Results obtained with L-NNA, 1400W, 7-NI, OxyHb, ODQ or Tiron showed that this response was mediated by products from endothelial NOS (eNOS) different from NO and without soluble guanylate cyclase activation, but it involved superoxide anions. Furthermore, Tiron or L-NNA reduced the levels of reactive oxygen species in contralateral carotids. Data suggest that balloon catheter injury promoted eNOS uncoupling in contralateral carotids, which generates superoxide rather than NO, and reduces phenylephrine-induced extracellular calcium mobilization, despite the hyper-reactivity to phenylephrine in contralateral carotids.
Assuntos
Angioplastia com Balão/efeitos adversos , Sinalização do Cálcio , Artérias Carótidas/enzimologia , Óxido Nítrico Sintase Tipo III/metabolismo , Animais , Sinalização do Cálcio/efeitos dos fármacos , Artérias Carótidas/efeitos dos fármacos , Artérias Carótidas/patologia , Artérias Carótidas/fisiopatologia , Masculino , Nitratos/metabolismo , Óxido Nítrico/metabolismo , Nitritos/metabolismo , Fenilefrina/farmacologia , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Vasoconstrição/efeitos dos fármacosRESUMO
The carotid artery has a pivotal role in the body since it supplies the head and neck with oxygenated blood. Alterations in the functional and structural integrity of these vessels can decrease blood flow to the brain. For this reason, it is important to understand how the carotid artery responds to various stimuli. The organ bath is a traditional experimental set-up that has been used extensively to investigate the (patho)physiology and pharmacology of in vitro tissue preparations including the rat carotid artery. Molecular biology developed from related fields such as biochemistry, genetics and biophysics is now considered an important tool for understanding physiological pathways in a variety of tissues. Several local and systemic factors regulate carotid reactivity, including vaso-active peptides, such as endothelin 1 (ET-1), angiotensin II (Ang II) and bradykinin (BK). These vaso-active peptides play a fundamental role in controlling the functional and structural integrity of the arterial wall and may be important in physiological processes and in pathological mechanisms underlying vascular diseases. In the rat carotid, these peptides induce vasoconstriction or relaxation by the release of endothelium-derived relaxing factors, such as nitric oxide and prostacyclin. Identification of such signal transduction processes is essential for understanding the mechanisms that regulate vascular smooth muscle cell function, both physiologically and pathophysiologically. The present review discusses the mechanisms of action, distribution of ET-1, Ang II and BK and their receptors in the rat carotid. With this purpose, data obtained in functional studies using classical pharmacological approaches as well as data obtained in molecular biology experiments are discussed.