RESUMO
O-GlcNAcylation is a modification that alters the function of numerous proteins. We hypothesized that augmented O-GlcNAcylation levels enhance myosin light chain kinase (MLCK) and reduce myosin light chain phosphatase (MLCP) activity, leading to increased vascular contractile responsiveness. The vascular responses were measured by isometric force displacement. Thoracic aorta and vascular smooth muscle cells (VSMCs) from rats were incubated with vehicle or with PugNAc, which increases O-GlcNAcylation. In addition, we determined whether proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation. PugNAc enhanced phenylephrine (PE) responses in rat aortas (maximal effect, 14.2±2 vs 7.9±1 mN for vehicle, n=7). Treatment with an MLCP inhibitor (calyculin A) augmented vascular responses to PE (13.4±2 mN) and abolished the differences in PE-response between the groups. The effect of PugNAc was not observed when vessels were preincubated with ML-9, an MLCK inhibitor (7.3±2 vs 7.5±2 mN for vehicle, n=5). Furthermore, our data showed that differences in the PE-induced contractile response between the groups were abolished by the activator of AMP-activated protein kinase (AICAR; 6.1±2 vs 7.4±2 mN for vehicle, n=5). PugNAc increased phosphorylation of myosin phosphatase target subunit 1 (MYPT-1) and protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17), which are involved in RhoA/Rho-kinase-mediated inhibition of myosin phosphatase activity. PugNAc incubation produced a time-dependent increase in vascular phosphorylation of myosin light chain and decreased phosphorylation levels of AMP-activated protein kinase, which decreased the affinity of MLCK for Ca2+/calmodulin. Our data suggest that proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation, favoring vascular contraction.
Assuntos
Animais , Masculino , Músculo Liso Vascular/fisiologia , Cadeias Leves de Miosina/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Vasoconstrição/fisiologia , Aorta Torácica , Acetilglucosamina/análogos & derivados , Acetilglucosamina/farmacologia , Acilação/efeitos dos fármacos , Acilação/fisiologia , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Azepinas/farmacologia , Western Blotting , Inibidores Enzimáticos/farmacologia , Hipoglicemiantes/farmacologia , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Quinase de Cadeia Leve de Miosina/metabolismo , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Oxazóis/farmacologia , Oximas/farmacologia , Fenilcarbamatos/farmacologia , Fenilefrina/agonistas , Fosforilação/efeitos dos fármacos , Fosforilação/fisiologia , Ratos Wistar , Ribonucleotídeos/farmacologia , Vasoconstrição/efeitos dos fármacos , Vasoconstritores/farmacologia , beta-N-Acetil-Hexosaminidases/antagonistas & inibidoresRESUMO
O-GlcNAcylation is a modification that alters the function of numerous proteins. We hypothesized that augmented O-GlcNAcylation levels enhance myosin light chain kinase (MLCK) and reduce myosin light chain phosphatase (MLCP) activity, leading to increased vascular contractile responsiveness. The vascular responses were measured by isometric force displacement. Thoracic aorta and vascular smooth muscle cells (VSMCs) from rats were incubated with vehicle or with PugNAc, which increases O-GlcNAcylation. In addition, we determined whether proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation. PugNAc enhanced phenylephrine (PE) responses in rat aortas (maximal effect, 14.2 ± 2 vs 7.9 ± 1 mN for vehicle, n=7). Treatment with an MLCP inhibitor (calyculin A) augmented vascular responses to PE (13.4 ± 2 mN) and abolished the differences in PE-response between the groups. The effect of PugNAc was not observed when vessels were preincubated with ML-9, an MLCK inhibitor (7.3 ± 2 vs 7.5 ± 2 mN for vehicle, n=5). Furthermore, our data showed that differences in the PE-induced contractile response between the groups were abolished by the activator of AMP-activated protein kinase (AICAR; 6.1 ± 2 vs 7.4 ± 2 mN for vehicle, n=5). PugNAc increased phosphorylation of myosin phosphatase target subunit 1 (MYPT-1) and protein kinase C-potentiated inhibitor protein of 17 kDa (CPI-17), which are involved in RhoA/Rho-kinase-mediated inhibition of myosin phosphatase activity. PugNAc incubation produced a time-dependent increase in vascular phosphorylation of myosin light chain and decreased phosphorylation levels of AMP-activated protein kinase, which decreased the affinity of MLCK for Ca(2+)/calmodulin. Our data suggest that proteins that play an important role in the regulation of MLCK and MLCP activity are directly affected by O-GlcNAcylation, favoring vascular contraction.
Assuntos
Músculo Liso Vascular/fisiologia , Cadeias Leves de Miosina/metabolismo , Processamento de Proteína Pós-Traducional/fisiologia , Vasoconstrição/fisiologia , Acetilglucosamina/análogos & derivados , Acetilglucosamina/farmacologia , Acilação/efeitos dos fármacos , Acilação/fisiologia , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacologia , Animais , Aorta Torácica , Azepinas/farmacologia , Western Blotting , Inibidores Enzimáticos/farmacologia , Hipoglicemiantes/farmacologia , Masculino , Toxinas Marinhas , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Quinase de Cadeia Leve de Miosina/metabolismo , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Oxazóis/farmacologia , Oximas/farmacologia , Fenilcarbamatos/farmacologia , Fenilefrina/agonistas , Fosforilação/efeitos dos fármacos , Fosforilação/fisiologia , Ratos Wistar , Ribonucleotídeos/farmacologia , Vasoconstrição/efeitos dos fármacos , Vasoconstritores/farmacologia , beta-N-Acetil-Hexosaminidases/antagonistas & inibidoresRESUMO
Obesity is strongly associated with high blood pressure, dyslipidemia, and type 2 diabetes. These conditions synergistically increase the risk of cardiovascular events. A number of central and peripheral abnormalities can explain the development or maintenance of high blood pressure in obesity. Of great interest is endothelial dysfunction, considered to be a primary risk factor in the development of hypertension. Additional mechanisms also related to endothelial dysfunction have been proposed to mediate the development of hypertension in obese individuals. These include: increase in both peripheral vasoconstriction and renal tubular sodium reabsorption, increased sympathetic activity and overactivation of both the renin-angiotensin system and the endocannabinoid system and insulin resistance. The discovery of new mechanisms regulating metabolic and vascular function and a better understanding of how vascular function can be influenced by these systems would facilitate the development of new therapies for treatment of obesity-associated hypertension.
Assuntos
Humanos , Endotélio Vascular/fisiopatologia , Hipertensão/fisiopatologia , Obesidade/fisiopatologia , Hipertensão/etiologia , Resistência à Insulina/fisiologia , Obesidade/complicações , Fatores de Risco , Sistema Renina-Angiotensina/fisiologia , Sistema Nervoso Simpático/fisiopatologiaRESUMO
Obesity is strongly associated with high blood pressure, dyslipidemia, and type 2 diabetes. These conditions synergistically increase the risk of cardiovascular events. A number of central and peripheral abnormalities can explain the development or maintenance of high blood pressure in obesity. Of great interest is endothelial dysfunction, considered to be a primary risk factor in the development of hypertension. Additional mechanisms also related to endothelial dysfunction have been proposed to mediate the development of hypertension in obese individuals. These include: increase in both peripheral vasoconstriction and renal tubular sodium reabsorption, increased sympathetic activity and overactivation of both the renin-angiotensin system and the endocannabinoid system and insulin resistance. The discovery of new mechanisms regulating metabolic and vascular function and a better understanding of how vascular function can be influenced by these systems would facilitate the development of new therapies for treatment of obesity-associated hypertension.
Assuntos
Endotélio Vascular/fisiopatologia , Hipertensão/fisiopatologia , Obesidade/fisiopatologia , Humanos , Hipertensão/etiologia , Resistência à Insulina/fisiologia , Obesidade/complicações , Sistema Renina-Angiotensina/fisiologia , Fatores de Risco , Sistema Nervoso Simpático/fisiopatologiaRESUMO
AIMS: Cytokines interfere with signaling pathways and mediators of vascular contraction. Endothelin-1 (ET-1) plays a major role on vascular dysfunction in conditions characterized by increased circulating levels of adipokines. In the present study we tested the hypothesis that the adipokine chemerin increases vascular contractile responses via activation of ET-1/ET-1 receptors-mediated pathways. MAIN METHODS: Male, 10-12 week-old Wistar rats were used. Endothelium-intact and endothelium-denuded aortic rings were incubated with chemerin (0.5 ng/mL or 5 ng/mL, for 1 or 24h), and isometric contraction was recorded. Protein expression was determined by Western blotting. KEY FINDINGS: Constrictor responses to phenylephrine (PE) and ET-1 were increased in vessels treated for 1h with chemerin. Chemerin incubation for 24h decreased PE contractile response whereas it increased the sensitivity to ET-1. Endothelium removal significantly potentiated chemerin effects on vascular contractile responses to PE and ET-1. Incubation with either an ERK1/2 inhibitor (PD98059) or ETA antagonist (BQ123) abolished chemerin effects on PE- and ET-1-induced vasoconstriction. Phosphorylation of MEK1/2 and ERK1/2 was significantly increased in vessels treated with chemerin for 1 and 24h. Phosphorylation of these proteins was further increased in vessels incubated with ET-1 plus chemerin. ET-1 increased MEK1/2, ERK1/2 and MKP1 protein expression to values observed in vessels treated with chemerin. SIGNIFICANCE: Chemerin increases contractile responses to PE and ET-1 via ERK1/2 activation. Our study contributes to a better understanding of the mechanisms by which the adipose tissue affects vascular function and, consequently, the vascular alterations present in obesity and related diseases.
Assuntos
Adipocinas/administração & dosagem , Aorta Torácica/efeitos dos fármacos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Adipocinas/metabolismo , Animais , Aorta Torácica/metabolismo , Western Blotting , Quimiocinas , Relação Dose-Resposta a Droga , Endotelina-1/administração & dosagem , Endotelina-1/metabolismo , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Flavonoides/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular , MAP Quinase Quinase 1/metabolismo , MAP Quinase Quinase 2/metabolismo , Masculino , Peptídeos Cíclicos/farmacologia , Fenilefrina/farmacologia , Fosforilação/efeitos dos fármacos , Ratos , Ratos Wistar , Fatores de TempoRESUMO
AIMS: Inflammation may have an important role in the beginning and in the progress of cardiovascular diseases. Testosterone exerts important effects on vascular function, which is altered in arterial hypertension. Thus, the aim of this study was to evaluate the influence of endogenous testosterone on leukocyte behavior in post-capillary venules of the mesenteric bed of spontaneously hypertensive rats (SHR). MAIN METHODS: 18 week-old intact SHR, castrated SHR and normotensive rats (intact Wistar) were used. Blood pressure was measured by tail plethysmography and serum testosterone levels by ELISA. Leukocyte rolling, adhesion and migration were evaluated in vivo in situ by intravital microscopy. KEY FINDINGS: Castration significantly reduced blood pressure and reversed the increased leukocyte rolling and adhesion observed in SHRs. Leukocyte counts and other hemodynamic parameters did not differ among groups. SHRs displayed increased protein expression of P-selectin and ICAM-1 in mesenteric venules when compared to intact Wistar. Castration of SHRs restored the protein expression of the cell adhesion molecules. SIGNIFICANCE: The findings of the present study demonstrate the critical role of endogenous testosterone mediating the effects of hypertension increasing leukocyte-endothelial cell interaction. Increased expression of cell adhesion molecules contribute to the effects of endogenous testosterone promoting increased leukocyte rolling and adhesion in SHRs.
Assuntos
Comunicação Celular , Células Endoteliais/citologia , Hipertensão/imunologia , Leucócitos/citologia , Ratos Endogâmicos SHR/imunologia , Testosterona/imunologia , Animais , Adesão Celular , Células Endoteliais/imunologia , Hemodinâmica , Hipertensão/genética , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/imunologia , Migração e Rolagem de Leucócitos , Leucócitos/imunologia , Masculino , Orquiectomia , Selectina-P/genética , Selectina-P/imunologia , RNA Mensageiro/genética , Ratos , Ratos Endogâmicos SHR/genética , Ratos Wistar , Vênulas/citologiaRESUMO
AIMS: Metformin is an insulin sensitizing agent with beneficial effects in diabetic patients on glycemic levels and in the cardiovascular system. We examined whether the metabolic changes and the vascular dysfunction in monosodium glutamate-induced obese non-diabetic (MSG) rats might be improved by metformin. MAIN METHODS: 16 week-old MSG rats were treated with metformin for 15 days and compared with age-matched untreated MSG and non-obese non-diabetic rats (control). Blood pressure, insulin sensitivity, vascular reactivity and prostanoid release in the perfused mesenteric arteriolar bed as well as nitric oxide production and reactive oxygen species generation in isolated mesenteric arteries were analyzed. KEY FINDINGS: 18-week-old MSG rats displayed higher Lee index, fat accumulation, dyslipidemia, insulin resistance and hyperinsulinemia. Metformin treatment improved these alterations. The norepinephrine-induced response, increased in the mesenteric arteriolar bed from MSG rats, was corrected by metformin. Indomethacin corrected the enhanced contractile response in MSG rats but did not affect metformin effects. The sensitivity to acetylcholine, reduced in MSG rats, was also corrected by metformin. Indomethacin corrected the reduced sensitivity to acetylcholine in MSG rats but did not affect metformin effects. The sensitivity to sodium nitroprusside was increased in preparations from metformin-treated rats. Metformin treatment restored both the reduced PGI2/TXA2 ratio and the increased reactive oxygen species generation in preparations from MSG rats. SIGNIFICANCE: Metformin improved the vascular function in MSG rats through reduction in reactive oxygen species generation, modulation of membrane hyperpolarization, correction of the unbalanced prostanoids release and increase in the sensitivity of the smooth muscle to nitric oxide.
Assuntos
Hipoglicemiantes/administração & dosagem , Artérias Mesentéricas/metabolismo , Metformina/administração & dosagem , Óxido Nítrico Sintase/metabolismo , Obesidade/tratamento farmacológico , Acetilcolina/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Modelos Animais de Doenças , Dislipidemias/tratamento farmacológico , Epoprostenol/metabolismo , Hiperinsulinismo/tratamento farmacológico , Indometacina/farmacologia , Insulina/sangue , Resistência à Insulina , Masculino , Artérias Mesentéricas/efeitos dos fármacos , Óxido Nítrico/análise , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/análise , Nitroprussiato/farmacologia , Norepinefrina/farmacologia , Obesidade/induzido quimicamente , Obesidade/fisiopatologia , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Glutamato de Sódio/administração & dosagem , Tromboxano A2/metabolismoRESUMO
Highly efficient mechanisms regulate intracellular calcium (Ca2+) levels. The recent discovery of new components linking intracellular Ca2+ stores to plasma membrane Ca2+ entry channels has brought new insight into the understanding of Ca2+ homeostasis. Stromal interaction molecule 1 (STIM1) was identified as a Ca2+ sensor essential for Ca2+ store depletion-triggered Ca2+ influx. Orai1 was recognized as being an essential component for the Ca2+ release-activated Ca2+ (CRAC) channel. Together, these proteins participate in store-operated Ca2+ channel function. Defective regulation of intracellular Ca2+ is a hallmark of several diseases. In this review, we focus on Ca2+ regulation by the STIM1/Orai1 pathway and review evidence that implicates STIM1/Orai1 in several pathological conditions including cardiovascular and pulmonary diseases, among others.
Assuntos
Humanos , Canais de Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Neoplasias/metabolismo , Doenças Cardiovasculares/metabolismo , Pneumopatias/metabolismoRESUMO
Highly efficient mechanisms regulate intracellular calcium (Ca2+) levels. The recent discovery of new components linking intracellular Ca2+ stores to plasma membrane Ca2+ entry channels has brought new insight into the understanding of Ca2+ homeostasis. Stromal interaction molecule 1 (STIM1) was identified as a Ca2+ sensor essential for Ca2+ store depletion-triggered Ca2+ influx. Orai1 was recognized as being an essential component for the Ca2+ release-activated Ca2+ (CRAC) channel. Together, these proteins participate in store-operated Ca2+ channel function. Defective regulation of intracellular Ca2+ is a hallmark of several diseases. In this review, we focus on Ca2+ regulation by the STIM1/Orai1 pathway and review evidence that implicates STIM1/Orai1 in several pathological conditions including cardiovascular and pulmonary diseases, among others.
Assuntos
Canais de Cálcio/metabolismo , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Neoplasias/metabolismo , Doenças Cardiovasculares/metabolismo , Humanos , Pneumopatias/metabolismo , Proteína ORAI1 , Molécula 1 de Interação EstromalRESUMO
Placentation starts with the formation of a spheroidal trophoblastic shell surrounding the embryo, thus facilitating both implantation into the uterine stroma and contact with maternal blood. Although it is known that diabetes increases the placental size and weight, the mechanisms responsible for this alteration are still poorly understood. In mammals, cellular proliferation occurs in parallel to placental development and it is possible that diabetes induces abnormal uncontrolled cell proliferation in the placenta similar to that seen in other organs (e.g. retina). To test this hypothesis, the objective of this work was to determine cell proliferation in different regions of the placenta during its development in a diabetic rat model. Accordingly, diabetes was induced on day 2 of pregnancy in Wistar rats by a single injection of alloxan (40 mg/kg i.v.). Placentas were collected on days 14, 17, and 20 postcoitum. Immunoperoxidase was used to identify Ki67 nuclear antigen in placental sections. The number of proliferating cells was determined in the total placental area as well as in the labyrinth, spongiotrophoblast and giant trophoblast cell regions. During the course of pregnancy, the number of Ki67 positive cells decreased in both control and diabetic rat placentas. However, starting from day 17 of pregnancy, the number of Ki67 positive cells in the labyrinth and spongiotrophoblast regions was higher in diabetic rat placentas as compared to control. The present results demonstrate that placentas from the diabetic rat model have a significantly higher number of proliferating cells in specific regions of the placenta and at defined developmental stages. It is possible that this increased cell proliferation promotes thickness of the placental barrier consequently affecting the normal maternal-fetal exchanges.
Assuntos
Diabetes Mellitus Experimental/patologia , Placenta/patologia , Placentação/fisiologia , Gravidez em Diabéticas/patologia , Animais , Biomarcadores/metabolismo , Proliferação de Células , Diabetes Mellitus Experimental/metabolismo , Feminino , Técnicas Imunoenzimáticas , Antígeno Ki-67/metabolismo , Troca Materno-Fetal/fisiologia , Tamanho do Órgão/fisiologia , Placenta/metabolismo , Gravidez , Gravidez em Diabéticas/metabolismo , Ratos , Ratos WistarRESUMO
BACKGROUND AND AIM: given that obesity is an independent risk factor for the development of cardiovascular diseases we decided to investigate the mechanisms involved in microvascular dysfunction using a monosodium glutamate (MSG)-induced model of obesity, which allows us to work on both normotensive and normoglycemic conditions. METHODS AND RESULTS: Male offspring of Wistar rats received MSG from the second to the sixth day after birth. Sixteen-week-old MSG rats displayed higher Lee index, fat accumulation, dyslipidemia and insulin resistance, with no alteration in glycemia and blood pressure. The effect of norepinephrine (NE), which was increased in MSG rats, was potentiated by L-nitro arginine methyl ester (L-NAME) or tetraethylammonium (TEA) and was reversed by indomethacin and NS-398. Sensitivity to acetylcholine (ACh), which was reduced in MSG rats, was further impaired by L-NAME or TEA, and was corrected by indomethacin, NS-398 and tetrahydrobiopterin (BH4). MSG rats displayed increased endothelium-independent relaxation to sodium nitroprusside. A reduced prostacyclin/tromboxane ratio was found in the mesenteric beds of MSG rats. Mesenteric arterioles of MSG rats also displayed reduced nitric oxide (NO) production along with increased reactive oxygen species (ROS) generation; these were corrected by BH4 and either L-NAME or superoxide dismutase, respectively. The protein expression of eNOS and cyclooxygenase (COX)-2 was increased in mesenteric arterioles from MSG rats. CONCLUSION: Obesity/insulin resistance has a detrimental impact on vascular function. Reduced NO bioavailability and increased ROS generation from uncoupled eNOS and imbalanced release of COX products from COX-2 play a critical role in the development of these vascular alterations.
Assuntos
Animais Recém-Nascidos , Microvasos/fisiopatologia , Óxido Nítrico/fisiologia , Obesidade/induzido quimicamente , Prostaglandinas/fisiologia , Glutamato de Sódio/administração & dosagem , Animais , Arteríolas/enzimologia , Arteríolas/metabolismo , Ciclo-Oxigenase 2/análise , Masculino , Mesentério/irrigação sanguínea , Óxido Nítrico Sintase Tipo III/análise , Obesidade/fisiopatologia , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismoRESUMO
Oscillatory contractile activity is an inherent property of blood vessels. Various cellular mechanisms have been proposed to contribute to oscillatory activity. Mouse small mesenteric arteries display a unique low frequency contractile oscillatory activity (1 cycle every 10-12 min) upon phenylephrine stimulation. Our objective was to identify mechanisms involved in this peculiar oscillatory activity. First-order mesenteric arteries were mounted in tissue baths for isometric force measurement. The oscillatory activity was observed only in vessels with endothelium, but it was not blocked by L-NAME (100 µM) or indomethacin (10 µM), ruling out the participation of nitric oxide and prostacyclin, respectively, in this phenomenon. Oscillatory activity was not observed in vessels contracted with K+ (90 mM) or after stimulation with phenylephrine plus 10 mM K+. Ouabain (1 to 10 µM, an Na+/K+-ATPase inhibitor), but not K+ channel antagonists [tetraethylammonium (100 µM, a nonselective K+ channel blocker), Tram-34 (10 µM, blocker of intermediate conductance K+ channels) or UCL-1684 (0.1 µM, a small conductance K+ channel blocker)], inhibited the oscillatory activity. The contractile activity was also abolished when experiments were performed at 20°C or in K+-free medium. Taken together, these results demonstrate that Na+/K+-ATPase is a potential source of these oscillations. The presence of α-1 and α-2 Na+/K+-ATPase isoforms was confirmed in murine mesenteric arteries by Western blot. Chronic infusion of mice with ouabain did not abolish oscillatory contraction, but up-regulated vascular Na+/K+-ATPase expression and increased blood pressure. Together, these observations suggest that the Na+/K+ pump plays a major role in the oscillatory activity of murine small mesenteric arteries.
Assuntos
Animais , Masculino , Camundongos , Endotélio Vascular/enzimologia , Hipertensão/fisiopatologia , Artérias Mesentéricas/enzimologia , ATPase Trocadora de Sódio-Potássio/fisiologia , Resistência Vascular/fisiologia , Endotélio Vascular/fisiologia , Inibidores Enzimáticos/farmacologia , Hipertensão/induzido quimicamente , Artérias Mesentéricas/fisiologia , Ouabaína/farmacologiaRESUMO
Oscillatory contractile activity is an inherent property of blood vessels. Various cellular mechanisms have been proposed to contribute to oscillatory activity. Mouse small mesenteric arteries display a unique low frequency contractile oscillatory activity (1 cycle every 10-12 min) upon phenylephrine stimulation. Our objective was to identify mechanisms involved in this peculiar oscillatory activity. First-order mesenteric arteries were mounted in tissue baths for isometric force measurement. The oscillatory activity was observed only in vessels with endothelium, but it was not blocked by L-NAME (100 microM) or indomethacin (10 microM), ruling out the participation of nitric oxide and prostacyclin, respectively, in this phenomenon. Oscillatory activity was not observed in vessels contracted with K+ (90 mM) or after stimulation with phenylephrine plus 10 mM K+. Ouabain (1 to 10 microM, an Na+/K+-ATPase inhibitor), but not K+ channel antagonists [tetraethylammonium (100 microM, a nonselective K+ channel blocker), Tram-34 (10 microM, blocker of intermediate conductance K+ channels) or UCL-1684 (0.1 microM, a small conductance K+ channel blocker)], inhibited the oscillatory activity. The contractile activity was also abolished when experiments were performed at 20 degrees C or in K+-free medium. Taken together, these results demonstrate that Na+/K+-ATPase is a potential source of these oscillations. The presence of alpha-1 and alpha-2 Na+/K+-ATPase isoforms was confirmed in murine mesenteric arteries by Western blot. Chronic infusion of mice with ouabain did not abolish oscillatory contraction, but up-regulated vascular Na+/K+-ATPase expression and increased blood pressure. Together, these observations suggest that the Na+/K+ pump plays a major role in the oscillatory activity of murine small mesenteric arteries.
Assuntos
Endotélio Vascular/enzimologia , Hipertensão/fisiopatologia , Artérias Mesentéricas/enzimologia , ATPase Trocadora de Sódio-Potássio/fisiologia , Resistência Vascular/fisiologia , Animais , Endotélio Vascular/fisiologia , Inibidores Enzimáticos/farmacologia , Hipertensão/induzido quimicamente , Masculino , Artérias Mesentéricas/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Ouabaína/farmacologiaRESUMO
BACKGROUND AND PURPOSE: There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries. EXPERIMENTAL APPROACH: Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1. KEY RESULTS: HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO. CONCLUSIONS AND IMPLICATIONS: Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.
Assuntos
Artérias Carótidas/fisiopatologia , Endotelina-1/fisiologia , Endotélio Vascular/fisiopatologia , Hiper-Homocisteinemia/metabolismo , Hiper-Homocisteinemia/fisiopatologia , Animais , Ácido Aspártico Endopeptidases/metabolismo , Cálcio/farmacologia , Artérias Carótidas/efeitos dos fármacos , Artérias Carótidas/metabolismo , Relação Dose-Resposta a Droga , Antagonistas do Receptor de Endotelina A , Antagonistas do Receptor de Endotelina B , Endotelina-1/biossíntese , Enzimas Conversoras de Endotelina , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Técnicas In Vitro , Masculino , Metaloendopeptidases/metabolismo , Óxidos de Nitrogênio/metabolismo , Óxidos de Nitrogênio/farmacologia , Ratos , Ratos Wistar , Receptor de Endotelina A/biossíntese , Receptor de Endotelina B/agonistas , Receptor de Endotelina B/biossíntese , Vasoconstrição/efeitos dos fármacos , Vasoconstrição/fisiologia , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologiaRESUMO
During embryo implantation, invasive trophoblast cells mediate embryo invasion into the decidualized stroma, forming a rich network of lacunae that connect the embryonic tissues to the maternal blood vessels. Placentation is probably guided by the composition and organization of the endometrial extracellular matrix. Certain pathological conditions that occur during pregnancy, including diabetes, have been linked to abnormal placental morphology and consequent fetal morbidity. We used immunoperoxidase techniques to identify members of the collagen, proteoglycan and glycoprotein families in the various compartments of the rat placenta and to determine whether experimentally induced diabetes affects placental morphology and alters the distribution of these molecules during pregnancy. Single injections of alloxan (40 mg kg(-1) i.v.) were used to induce diabetes on day 2 of pregnancy in Wistar rats. Placentas were collected on days 14, 17, and 20. Type I and III collagen, as well as the proteoglycans decorin and biglycan, were found to be distributed throughout the placentas of control and diabetic rats. In both groups, laminin expression decreased at the end of pregnancy. In contrast, fibronectin was detected in the labyrinth region of diabetic rats at all gestational stages studied, whereas it was detected only at term pregnancy in the placentas of control rats. These results show for the first time that some extracellular matrix molecules are modulated during placental development. However, as diabetic rats presented increased fibronectin deposition exclusively in the labyrinth region, we speculate that diabetes alters the microenvironment at the maternal-fetal interface, leading to developmental abnormalities in the offspring.
Assuntos
Diabetes Mellitus Experimental/patologia , Diabetes Gestacional/patologia , Proteínas da Matriz Extracelular/análise , Placentação , Animais , Biglicano , Colágeno Tipo I/análise , Colágeno Tipo III/análise , Decorina , Endométrio/química , Feminino , Fibronectinas/análise , Técnicas Imunoenzimáticas , Laminina/análise , Placenta/química , Gravidez , Proteoglicanas/análise , Ratos , Ratos WistarRESUMO
BACKGROUND AND PURPOSE: Epidemiological data suggest that the risk of ethanol-associated cardiovascular disease is greater in men than in women. This study investigates the mechanisms underlying gender-specific vascular effects elicited by chronic ethanol consumption in rats. EXPERIMENTAL APPROACH: Vascular reactivity experiments using standard muscle bath procedures were performed on isolated thoracic aortae from rats. mRNA and protein for inducible NO synthase (iNOS) and for endothelial NOS (eNOS) was assessed by RT-PCR or western blotting, respectively. KEY RESULTS: In male rats, chronic ethanol consumption enhanced phenylephrine-induced contraction in both endothelium-intact and denuded aortic rings. However, in female rats, chronic ethanol consumption enhanced phenylephrine-induced contraction only in endothelium denuded aortic rings. After pre-incubation of endothelium-intact rings with L-NAME, both male and female ethanol-treated rats showed larger phenylephrine-induced contractions in aortic rings, compared to the control group. Acetylcholine-induced relaxation was not affected by ethanol consumption. The effects of ethanol on responses to phenylephrine were similar in ovariectomized (OVX) and intact (non-OVX) female rats. In the presence of aminoguanidine, but not 7-nitroindazole, the contractions to phenylephrine in rings from ethanol-treated female rats were greater than that found in control tissues in the presence of the inhibitors. mRNA levels for eNOS and iNOS were not altered by ethanol consumption. Ethanol intake reduced eNOS protein levels and increased iNOS protein levels in aorta from female rats. CONCLUSIONS AND IMPLICATIONS: Gender differences in the vascular effects elicited by chronic ethanol consumption were not related to ovarian hormones but seemed to involve the upregulation of iNOS.
Assuntos
Depressores do Sistema Nervoso Central/farmacologia , Endotélio Vascular/efeitos dos fármacos , Etanol/farmacologia , Óxido Nítrico Sintase Tipo II/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Animais , Aorta Torácica/metabolismo , Endotélio Vascular/metabolismo , Feminino , Técnicas In Vitro , Masculino , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/efeitos dos fármacos , Óxido Nítrico Sintase Tipo III/metabolismo , Ovariectomia , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Fatores Sexuais , Vasoconstrição/efeitos dos fármacos , Vasodilatação/efeitos dos fármacosRESUMO
The present work evaluated histopathological aspects in experimental envenomation of dogs with Crotalus durissus terrificus venom. Twenty-eight mixed breed adult dogs were divided into three groups of seven animals each: Group I - only venom; Group II - venom + 50ml antiophidic serum + fluid therapy; Group III - venom + 50ml antiophidic serum + fluid therapy + urine alkalization. Lyophilized venom of Crotalus durissus terrificus was reconstituted in saline solution and inoculated subcutaneously at the dose of 1mg/kg body weight. Three animals of each group were subjected to euthanasia, and their muscular tissue, brain, spleen, kidneys, heart, lungs, stomach, small and large intestines, and popliteal lymph node fragments were collected for histopathological evaluation. There was myonecrosis in the inoculated limb, renal tubular degeneration, lymphoid hyperplasia of spleen, and unspecific reactive hepatitis. These results show the antigenicity and action of the venom on the immune system.
RESUMO
The present work evaluated histopathological aspects in experimental envenomation of dogs with Crotalus durissus terrificus venom. Twenty-eight mixed breed adult dogs were divided into three groups of seven animals each: Group I - only venom; Group II - venom + 50ml antiophidic serum + fluid therapy; Group III - venom + 50ml antiophidic serum + fluid therapy + urine alkalization. Lyophilized venom of Crotalus durissus terrificus was reconstituted in saline solution and inoculated subcutaneously at the dose of 1mg/kg body weight. Three animals of each group were subjected to euthanasia, and their muscular tissue, brain, spleen, kidneys, heart, lungs, stomach, small and large intestines, and popliteal lymph node fragments were collected for histopathological evaluation. There was myonecrosis in the inoculated limb, renal tubular degeneration, lymphoid hyperplasia of spleen, and unspecific reactive hepatitis. These results show the antigenicity and action of the venom on the immune system.
Assuntos
Animais , Masculino , Feminino , Cães/anatomia & histologia , Venenos de Crotalídeos/efeitos adversos , Venenos de Crotalídeos/toxicidadeRESUMO
Hyperglycaemia is a primary cause of vascular complications in diabetes. A hallmark of these vascular complications is endothelial cell dysfunction, which is partly due to reduced production of nitric oxide. The aim of this study was to verify the influence of improved glycaemic control with chlorpropamide on microvascular reactivity, endothelial nitric oxide synthase (e-NOS) expression, and NOS activity in neonatal streptozotocin-induced diabetic rats (n-STZ). Diabetes was induced by STZ injection into neonates Wistar rats. n-STZ diabetic rats were treated with chlorpropamide (200 mg kg(-1), 15 days, by gavage). The changes in mesenteric arteriolar and venular diameters were determined in anaesthetized control and n-STZ diabetic rats, before and after topical application of acetylcholine, bradykinin and sodium nitroprusside (SNP). We also assessed e-NOS expression (using polymerase chain reaction after reverse transcription of mRNAs into cDNAs) and NOS activity (conversion of L-arginine to citrulline) in the mesenteric vascular bed of chlorpropamide-treated n-STZ, vehicle-treated n-STZ, and control rats. In n-STZ, chlorpropamide treatment reduced high glycaemic levels, improved glucose tolerance and homoeostatic model assessment (HOMA-beta), and restored NOS activity. Impaired vasodilator responses of arterioles and venules to acetylcholine, bradykinin and SNP were partially corrected by chlorpropamide treatment in n-STZ. We concluded that improved metabolic control and restored NOS activity might be collaborating with improved microvascular reactivity found in chlorpropamide-treated n-STZ.
Assuntos
Glicemia/efeitos dos fármacos , Clorpropamida/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Hipoglicemiantes/farmacologia , Óxido Nítrico Sintase/efeitos dos fármacos , Acetilcolina/farmacologia , Animais , Bradicinina/farmacologia , Diabetes Mellitus Experimental/fisiopatologia , Regulação da Expressão Gênica , Masculino , Microcirculação/efeitos dos fármacos , Microcirculação/metabolismo , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo III/efeitos dos fármacos , Óxido Nítrico Sintase Tipo III/metabolismo , Nitroprussiato/farmacologia , RNA Mensageiro , Ratos , Ratos Wistar , EstreptozocinaRESUMO
The present work shows laboratory aspects, electrocardiogram and histopathology results during experimental envenomation by Crotalus durissus terrificus in dogs treated with antiophidic serum. Twenty-one dogs were divided into three groups of seven animals each. Group I received 1mg/kg venom (sc); Group II received 1mg/kg venom (sc), 50mg antiophidic serum (iv) and fluid therapy including 0.9% NaCl solution (iv); and Group III received 1mg/kg venom (sc), 50mg antiophidic serum (iv) and fluid therapy including 0.9% NaCl solution containing sodium bicarbonate diluted to the dose of 4mEq/kg. Urinalysis showed brown urine, proteinuria, occult blood and myoglobinuria. Respiratory acidosis and hypotension were also observed. At the venom inoculation site, there was discreet edema, popliteal lymph node response, musculature presenting whitish areas and necrotic myositis with myoregenerative activity. There was not evidence of electrocardiographical and biochemical alterations.