RESUMO
OBJECTIVE: To analyze the effects of estrogen alone or in combination with progestogens and tibolone (TIB) on the expression of the extracellular matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9), of perlecan, and of heparanase (HPSE) of the vascular walls of the carotid arteries. METHODS: A total of 30 250-day-old ovariectomized Wistar rats were orally treated for 5 weeks with: a) 1 mg/kg of estradiol benzoate (EB); b) EB + 0.2 mg/kg of medroxyprogesterone acetate (MPA); c) EB + 0.2mg/kg of norethisterone acetate (NETA); d) EB + 2 mg/kg of dydrogesterone (DI); e) 1 mg/kg of TIB; f) placebo (CTR). Following treatment, the expression of mRNA for MMP-2, MMP-9, and HPSE was analyzed by real-time polymerase chain-reaction (PCR), and the expression of MMP-2, of MMP-9, of tissue inhibitor of metalloproteinase 2 (TIMP-2), and of perlecan was quantified by immunohistochemistry in the carotid arteries. RESULTS: The groups showed significant differences on mRNA HPSE expression (p = 0.048), which was higher in the EB, EB + MPA, and TIB groups. There was no statistically significant difference in mRNA MMP-2 or MMP-9 expression. The immunohistochemical expression of MMP-2, of TIMP-2, of MMP-9, of HPSE, and of perlecan showed no differences between groups. CONCLUSION: Estradiol alone or associated with MPA and TIB treatment can increase mRNA HSPE expression of the walls of the carotid arteries in ovariectomized rats.
OBJETIVO: Analisar os efeitos do estrogênio isolado ou em combinação com progestogênios e tibolona (TIB) na expressão das metaloproteinases 2 e 9 da matriz extracelular (MMP-2 e MMP-9), da perlecan e da heparanase (HPSE) das paredes vasculares das artérias carótidas. MéTODOS: Trinta ratas Wistar ovariectomizadas com 250 dias de idade foram tratadas oralmente por 5 semanas com: a) 1 mg/kg de benzoato de estradiol (EB); b) EB + 0,2 mg/kg de acetato de medroxiprogesterona (MPA); c) EB + 0,2mg/kg de acetato de noretisterona (NETA); d) EB + 2 mg/kg de didrogesterona (DI); e) 1 mg/kg de TIB; f) placebo (CTR). Após o tratamento, a expressão de mRNA para MMP-2, MMP-9, e HPSE foi analisada por reação em cadeia da polimerase (RCP) em tempo real, e a expressão de MMP-2, MMP-9, inibidor tecidual de metaloproteinase 2 (TIMP-2), e de perlecan foi quantificado por imunohistoquímica em artérias carótidas. RESULTADOS: Os grupos apresentaram diferenças significativas na expressão do mRNA HPSE (p = 0,048), sendo maiores nos grupos EB, EB + MPA e TIB. Não houve diferença estatisticamente significativa nas expressões de mRNA MMP-2 ou MMP-9. A expressão imunohistoquímica de MMP-2, TIMP-2, MMP-9, HPSE e perlecan não mostrou diferenças entre os grupos. CONCLUSãO: O estradiol isolado ou associado ao tratamento com MPA e TIB pode aumentar a expressão de mRNA HSPE nas paredes das artérias carótidas em ratas ovariectomizadas.
Assuntos
Artérias Carótidas/enzimologia , Contraceptivos Hormonais/farmacologia , Estradiol/análogos & derivados , Heparina Liase/efeitos dos fármacos , Norpregnenos/farmacologia , Progestinas/farmacologia , Administração Oral , Animais , Artérias Carótidas/efeitos dos fármacos , Contraceptivos Hormonais/administração & dosagem , Estradiol/administração & dosagem , Estradiol/farmacologia , Terapia de Reposição de Estrogênios , Feminino , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Proteoglicanas de Heparan Sulfato/genética , Proteoglicanas de Heparan Sulfato/metabolismo , Heparina Liase/genética , Heparina Liase/metabolismo , Metaloproteinase 2 da Matriz/efeitos dos fármacos , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/efeitos dos fármacos , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Modelos Animais , Norpregnenos/administração & dosagem , Ovariectomia , Progestinas/administração & dosagem , Ratos , Ratos WistarRESUMO
Abstract Objective To analyze the effects of estrogen alone or in combination with progestogens and tibolone (TIB) on the expression of the extracellular matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9), of perlecan, and of heparanase (HPSE) of the vascular walls of the carotid arteries. Methods A total of 30 250-day-old ovariectomized Wistar rats were orally treated for 5 weeks with: a) 1 mg/kg of estradiol benzoate (EB); b) EB + 0.2 mg/kg of medroxyprogesterone acetate (MPA); c) EB + 0.2mg/kg of norethisterone acetate (NETA); d) EB + 2 mg/kg of dydrogesterone (DI); e) 1 mg/kg of TIB; f) placebo (CTR). Following treatment, the expression of mRNA for MMP-2, MMP-9, and HPSE was analyzed by realtime polymerase chain-reaction (PCR), and the expression of MMP-2, of MMP-9, of tissue inhibitor of metalloproteinase 2 (TIMP-2), and of perlecan was quantified by immunohistochemistry in the carotid arteries. Results The groups showed significant differences on mRNA HPSE expression (p = 0.048), which was higher in the EB, EB + MPA, and TIB groups. There was no statistically significant difference in mRNA MMP-2 or MMP-9 expression. The immunohistochemical expression of MMP-2, of TIMP-2, of MMP-9, of HPSE, and of perlecan showed no differences between groups. Conclusion Estradiol alone or associated with MPA and TIB treatment can increase mRNA HSPE expression of the walls of the carotid arteries in ovariectomized rats.
Resumo Objetivo Analisar os efeitos do estrogênio isolado ou em combinação com progestogênios e tibolona (TIB) na expressão das metaloproteinases 2 e 9 da matriz extracelular (MMP-2 e MMP-9), da perlecan e da heparanase (HPSE) das paredes vasculares das artérias carótidas. Métodos Trinta ratas Wistar ovariectomizadas com 250 dias de idade foram tratadas oralmente por 5 semanas com: a) 1 mg/kg de benzoato de estradiol (EB); b) EB + 0,2 mg/kg de acetato de medroxiprogesterona (MPA); c) EB + 0,2mg/kg de acetato de noretisterona (NETA); d) EB + 2 mg/kg de didrogesterona (DI); e) 1 mg/kg de TIB; f) placebo (CTR). Após o tratamento, a expressão de mRNA para MMP-2, MMP- 9, e HPSE foi analisada por reação em cadeia da polimerase (RCP) em tempo real, e a expressão de MMP-2, MMP-9, inibidor tecidual de metaloproteinase 2 (TIMP-2), e de perlecan foi quantificado por imunohistoquímica em artérias carótidas. Resultados Os grupos apresentaram diferenças significativas na expressão do mRNA HPSE (p = 0,048), sendo maiores nos grupos EB, EB + MPA e TIB. Não houve diferença estatisticamente significativa nas expressões de mRNA MMP-2 ou MMP-9. A expressão imunohistoquímica de MMP-2, TIMP-2, MMP-9, HPSE e perlecan não mostrou diferenças entre os grupos. Conclusão O estradiol isolado ou associado ao tratamento com MPA e TIB pode aumentar a expressão de mRNA HSPE nas paredes das artérias carótidas em ratas ovariectomizadas.
Assuntos
Animais , Feminino , Ratos , Progestinas/farmacologia , Artérias Carótidas/enzimologia , Heparina Liase/efeitos dos fármacos , Estradiol/análogos & derivados , Contraceptivos Hormonais/farmacologia , Norpregnenos/farmacologia , Progestinas/administração & dosagem , Ovariectomia , Artérias Carótidas/efeitos dos fármacos , Terapia de Reposição de Estrogênios , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Administração Oral , Ratos Wistar , Heparina Liase/genética , Heparina Liase/metabolismo , Proteoglicanas de Heparan Sulfato/genética , Proteoglicanas de Heparan Sulfato/metabolismo , Metaloproteinase 2 da Matriz/efeitos dos fármacos , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/efeitos dos fármacos , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Modelos Animais , Estradiol/administração & dosagem , Estradiol/farmacologia , Contraceptivos Hormonais/administração & dosagem , Norpregnenos/administração & dosagemRESUMO
PURPOSE: To evaluated the role of oxidative stress on aging process in patients submitted to carotid endarterectomy. METHODS: Twenty patients were divided into two groups: older group (≥ 70 years old); and the younger group (< 70 years old). We evaluated the reactive oxygen species (ROS) concentration, nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase, superoxide dismutase (SOD) and catalase (CAT) activities as so as nitrite levels in fragments of carotid arteries harvested during carotid endarterectomy for treatment of high grade carotid stenosis. RESULTS: We observed a higher levels of ROS and NADPH oxidase activity in the older group (p<0.05). Furthermore, the nitrite concentration was lower in the older group (14.55 ± 5.61 x 10-3 versus 26.42 ± 8.14 x 10-3 µM; p=0.0123). However, the activities of antioxidant enzymes (CAT and SOD) were similar in both the groups. CONCLUSIONS: : Arterial aging is associated with increased concentrations of oxygen species and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity as so as nitrite reduction in human carotid artery specimens. Maybe therapies that block NADPH oxidase activity and enhance nitrite stores would be a good strategy to reduce the effect of oxidative stress in arterial aging.
Assuntos
Envelhecimento/fisiologia , Artérias Carótidas/fisiologia , Endarterectomia das Carótidas , Estresse Oxidativo/fisiologia , Idoso , Idoso de 80 Anos ou mais , Artérias Carótidas/enzimologia , Catalase/metabolismo , Doença da Artéria Coronariana/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , NADP/análise , Espécies Reativas de Oxigênio/análise , Superóxido Dismutase/metabolismoRESUMO
ABSTRACT PURPOSE: To evaluated the role of oxidative stress on aging process in patients submitted to carotid endarterectomy. METHODS: Twenty patients were divided into two groups: older group (≥ 70 years old); and the younger group (< 70 years old). We evaluated the reactive oxygen species (ROS) concentration, nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase, superoxide dismutase (SOD) and catalase (CAT) activities as so as nitrite levels in fragments of carotid arteries harvested during carotid endarterectomy for treatment of high grade carotid stenosis. RESULTS: We observed a higher levels of ROS and NADPH oxidase activity in the older group (p<0.05). Furthermore, the nitrite concentration was lower in the older group (14.55 ± 5.61 x 10-3 versus 26.42 ± 8.14 x 10-3 µM; p=0.0123). However, the activities of antioxidant enzymes (CAT and SOD) were similar in both the groups. CONCLUSIONS : Arterial aging is associated with increased concentrations of oxygen species and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity as so as nitrite reduction in human carotid artery specimens. Maybe therapies that block NADPH oxidase activity and enhance nitrite stores would be a good strategy to reduce the effect of oxidative stress in arterial aging.
Assuntos
Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Artérias Carótidas/fisiologia , Endarterectomia das Carótidas , Estresse Oxidativo/fisiologia , Superóxido Dismutase/metabolismo , Doença da Artéria Coronariana/cirurgia , Artérias Carótidas/enzimologia , Catalase/metabolismo , Espécies Reativas de Oxigênio/análise , NADP/análiseRESUMO
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
AIM: To study the effects of estrogen therapy on the expression of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) and perlecan in the vascular wall. METHODS: Twenty 180-day-old Wistar rats were castrated and treated 1 week later for a period of 4 weeks with one of the following: (1) placebo; (2) 0.5 µg/day estradiol benzoate (E(2)B); (3) 5 µg/day E(2)B; (4) 50 µg/day E(2)B. A fifth group consisted of rats that had not been castrated. Following treatment, expression of MMP-2 and MMP-9 mRNA (MMP-2([RNA]) and MMP-9([RNA]), respectively) was analyzed by real-time PCR, and expression of MMP-2 (MMP-2([IH])), MMP-9 (MMP-9([IH])) and perlecan was quantified by immunohistochemistry, in carotid walls. RESULTS: There were no differences among castrated groups for MMP-2([RNA]) (p = 0.1969) and for MMP-9([RNA]) (p = 0.1828); however, a correlation was observed between E(2)B dose and MMP-9([RNA]) levels (r = 0.471, p = 0.018). Differences among groups were observed for MMP-2([IH]), MMP-9([IH]) and perlecan (p < 0.0001), wherein higher levels were observed in animals treated with estrogen therapy, correlating with E(2)B doses in the case of MMP-9 (r = 0.441, p = 0.026) and perlecan (r = 0.574, p = 0.005). CONCLUSIONS: Estrogen therapy correlates with higher levels of MMP-2, MMP-9 and perlecan in the extracellular matrix of carotid walls in castrated rats, in a dose-dependent manner. There was a dose-response effect of E(2)B on the expression of MMP-9 mRNA and, possibly, MMP-2 mRNA.
Assuntos
Artérias Carótidas/metabolismo , Estradiol/análogos & derivados , Estrogênios/farmacologia , Proteoglicanas de Heparan Sulfato/metabolismo , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Análise de Variância , Animais , Artérias Carótidas/enzimologia , Relação Dose-Resposta a Droga , Estradiol/administração & dosagem , Estradiol/farmacologia , Estrogênios/administração & dosagem , Feminino , Expressão Gênica/efeitos dos fármacos , Proteoglicanas de Heparan Sulfato/genética , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 9 da Matriz/genética , Ovariectomia , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Estatísticas não ParamétricasRESUMO
Quiescin sulfhydryl oxidases (QSOXs) catalyze the formation of disulfide bonds in peptides and proteins, and in vertebrates comprise two proteins: QSOX1 and QSOX2. QSOX1, the most extensively studied type, has been implicated in protein folding, production of extracellular matrix, redox regulation, protection from apoptosis, angiogenesis, and cell differentiation. Atherosclerosis is an immunopathological condition in which redox processes, apoptosis, cell differentiation, and matrix secretion/maturation have critical roles. Considering these data, we hypothesized that QSOX1 could be involved in this disease, possibly reducing apoptosis and angiogenesis inside the plaque. QSOX1 labeling in normal human carotid vessels showed predominant expression by endothelium, subendothelium, and adventitia. In atherosclerotic plaques, however, QSOX1 was highly expressed in macrophages at the lipid core. QSOX1 expression was also studied in terms of mRNA and protein in cell types present in plaques under apoptotic or activating stimuli, emulating conditions found in the atherosclerotic process. QSOX1 mRNA increased in endothelial cells and macrophages after the induction of apoptosis. At the protein level, the correlation between apoptosis and QSOX1 expression was not evident in all cell types, possibly because of a rapid secretion of QSOX1. Our results propose for the first time possible roles for QSOX1 in atherosclerosis, being upregulated in endothelial cells and macrophages by apoptosis and cell activation, and possibly controlling these processes, as well as angiogenesis. The quantitative differences in QSOX1 induction may depend on the cell type and also on local factors.
Assuntos
Apoptose , Oxirredutases atuantes sobre Doadores de Grupo Enxofre/metabolismo , Placa Aterosclerótica/enzimologia , Placa Aterosclerótica/patologia , Angiotensina II/farmacologia , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Apoptose/efeitos dos fármacos , Western Blotting , Brefeldina A/farmacologia , Camptotecina/farmacologia , Artérias Carótidas/efeitos dos fármacos , Artérias Carótidas/enzimologia , Artérias Carótidas/patologia , Diferenciação Celular/efeitos dos fármacos , Células HeLa , Células Endoteliais da Veia Umbilical Humana/citologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Imuno-HistoquímicaRESUMO
Mounting evidence suggest that tissue levels of angiotensin (ANG) II are maintained in animals submitted to chronic angiotensin-converting enzyme (ACE) inhibitor treatment. We examined the expression levels of transcripts for elastase-2, a chymostatin-sensitive serine protease identified as the alternative pathway for ANG II generation from ANG I in the rat vascular tissue and the relative role of ACE-dependent and -independent pathways in generating ANG II in the rat isolated carotid artery rings of spontaneously hypertensive rats (SHR) and Wistar normotensive rats (WNR) treated with enalapril for 7 days. Enalapril treatment decreased blood pressure of SHR only and resulted in significantly more elastase-2 mRNA expression in carotid artery of both enalapril-treated WNR and SHR. Captopril induced a comparable rightward shift of concentration-response curves to ANG I in vehicle and enalapril-treated rats, although this effect was of lesser magnitude in SHR group. Chymostatin induced a rightward shift of the dose response to ANG I in vehicle-treated and a decrease in maximal effect of 22% in enalapril-treated WNR group. Maximal response induced by ANG I was remarkably reduced by chymostatin in enalapril-treated SHR carotid artery (by 80%) compared with controls (by 23%). Our data show that chronic ACE inhibition was associated with augmented functional role of non-ACE pathway in generating ANG II and increased elastase-2 gene expression, suggesting that this protease may contribute as an alternative pathway for ANG II generation when ACE is inhibited in the rat vascular tissue.
Assuntos
Angiotensina II/metabolismo , Angiotensina I/metabolismo , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Anti-Hipertensivos/farmacologia , Artérias Carótidas/efeitos dos fármacos , Enalapril/farmacologia , Hipertensão/tratamento farmacológico , Serina Endopeptidases/metabolismo , Análise de Variância , Animais , Pressão Sanguínea/efeitos dos fármacos , Artérias Carótidas/enzimologia , Artérias Carótidas/fisiopatologia , Modelos Animais de Doenças , Hipertensão/enzimologia , Hipertensão/fisiopatologia , Imuno-Histoquímica , Masculino , Reação em Cadeia da Polimerase , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos SHR , Ratos Wistar , Serina Endopeptidases/genética , Fatores de Tempo , Regulação para Cima , Vasoconstrição/efeitos dos fármacosRESUMO
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
Homocysteine is an independent risk factor for coronary heart disease, as well as for cerebrovascular and peripheral vascular diseases. The purpose of this study was to investigate the effects of hyperhomocysteinemia (HHcy) on vascular reactivity within carotid artery segments isolated from ovariectomized female rats. Treatment with DL-Hcy thiolactone (1 g/kg body weight per day) reduced the phenylephrine-induced contraction of denuded rings. However, the treatment did not alter KCl-induced contractions, or relaxations induced by sodium nitroprusside or acetylcholine. We report elevated expressions of iNOS, eNOS, and nitrotyrosine in homocysteine-treated rat artery sections. Moreover, the inhibition of NOS by L-NAME, 1,400 W, or L-NNA restored phenylephrine-induced vasoconstriction in carotid artery segments from Hcy-treated rats. In conclusion, our findings show that severe HHCy can promote an acute decrease in the endothelium-independent contractile responses of carotid arteries to adrenergic agonists. This effect was restored by nitric oxide synthase inhibitors, which further supports the involvement of nitric oxide in HHcy-derived vascular dysfunction.