Thromboxane-dependent coronary vasoconstriction in obese mice: Role of peroxynitrite.

Obesity leads to chronic oxidative stress promoting the development of cardiovascular diseases including coronary artery disease and endothelial dysfunction. Increased reactive oxygen species production associated with obesity might lead to endothelial dysfunction through cyclooxygenase (COX) pathway. We evaluated arachidonic acid (AA)-dependent coronary vascular responses and explored COX metabolism in obese C57BL/6 mice. In response to arachidonic acid (AA), isolated hearts from obese mice showed increased vasoconstriction compared with control mice. Released thromboxane (TX) A2 during AA-induced vasoconstriction phase was increased in heart perfusates from obese mice. Indomethacin and 1-benzylimidazole, both reduced vasoconstriction response in control and obese mice. Vasoconstriction response to TXA2 mimetic analog U46619 was 2.7 higher in obese mice. Obesity increased COX-2, TXS and TX receptor protein expression as well as oxidative stress evaluated by nitrotyrosine and peroxynitrite levels, compared with control mice. Obese mice treated with FeTMPyP, a peroxynitrite scavenger, reversed all these parameters to control levels. These data suggest that alterations in COX pathway may be associated with increased generation of free radicals, including peroxynitrite, that result from the oxidative stress observed in obesity.

Protective Effects of Baicalin on Experimental Myocardial Infarction in Rats.

OBJECTIVE: This study aimed to investigate the protective effects of baicalin on myocardial infarction in rats and explore the related mechanisms. METHODS: Fifty Sprague Dawley rats were randomly divided into the control, model, and low-, medium- and high-dose baicalin groups. The latter 3 groups were intraperitoneally injected with baicalin, with a dose of 12.5, 25 and 50 mg/kg, respectively. Then, the myocardial infarction model was established. The hemodynamic of rats was tested, the serum lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), prostacyclin (PGI2) and thromboxane A2 (TXA2) were determined, the myocardial superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected, and the myocardial B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X (Bax) protein expressions were determined. RESULTS: Compared with the model group, in the high-dose baicalin group the ST segment height and LVEDP were significantly decreased (P<0.05), the LVSP was significantly increased (P<0.05), the serum LDH, CK-MB and TXA2 levels were significantly decreased (P<0.05), the PGI2 level was significantly increased (P<0.05), the myocardial SOD level was significantly increased (P<0.05), and the myocardial MDA level was significantly decreased (P<0.05); the myocardial Bcl-2 protein level was significantly increased, and the Bax protein level was significantly decreased (P<0.05). CONCLUSION: Baicalin has protective effects on myocardial infarction in rats. The possible mechanisms may be related to its resistance to oxidative stress, and up-regulation of Bcl-2 protein expression and down-regulation of Bax protein expression in myocardial tissue.

The effects of inhaled NO on plasma vasoactive factor and CTnI level in rabbits with acute massive pulmonary embolism1.

PURPOSE: To investigate changes in the plasma concentrations of cardiac troponin I (CTnI), thromboxane A2 (TXA2), prostaglandin I2 (PGI2) and endothelin-1 (ET-1) in rabbits with massive pulmonary embolism (AMPE) and the impact of nitric oxide inhalation (NOI) on these indices. METHODS: A total of 30 Japanese rabbits were used to construct an MPE model and were divided into 3 groups equally (n=10), including an EXP group (undergoing modeling alone), an NOI group (receiving NOI 2 h post-modeling) and a CON group (receiving intravenous physiological saline). RESULTS: In the model group, plasma concentration of CTnI peaked at 16 h following modeling (0.46±0.10 µg/ml) and significantly decreased following NOI. Plasma levels of TXB2, PGI2 and ET-1 peaked at 12, 16 and 8 h following modeling, respectively, and significantly decreased at different time points (0, 2, 4, 8, 12, 16, 20 and 24 h) following NOI. A significant correlation was observed between the peak plasma CTnI concentration and peak TXB2, 6-keto prostaglandin F1α and ET-1 concentrations in the model and NOI groups. CONCLUSION: Increases in plasma TXA2, PGI2 and ET-1 levels causes myocardial damage in a rabbit model of AMPE; however, NOI effectively down regulates the plasma concentration of these molecules to produce a myocardial-protective effect.

Protective effects of baicalin on experimental myocardial infarction in rats

Abstract Objective: This study aimed to investigate the protective effects of baicalin on myocardial infarction in rats and explore the related mechanisms. Methods: Fifty Sprague Dawley rats were randomly divided into the control, model, and low-, medium- and high-dose baicalin groups. The latter 3 groups were intraperitoneally injected with baicalin, with a dose of 12.5, 25 and 50 mg/kg, respectively. Then, the myocardial infarction model was established. The hemodynamic of rats was tested, the serum lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), prostacyclin (PGI2) and thromboxane A2 (TXA2) were determined, the myocardial superoxide dismutase (SOD) and malondialdehyde (MDA) levels were detected, and the myocardial B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X (Bax) protein expressions were determined. Results: Compared with the model group, in the high-dose baicalin group the ST segment height and LVEDP were significantly decreased (P<0.05), the LVSP was significantly increased (P<0.05), the serum LDH, CK-MB and TXA2 levels were significantly decreased (P<0.05), the PGI2 level was significantly increased (P<0.05), the myocardial SOD level was significantly increased (P<0.05), and the myocardial MDA level was significantly decreased (P<0.05); the myocardial Bcl-2 protein level was significantly increased, and the Bax protein level was significantly decreased (P<0.05). Conclusion: Baicalin has protective effects on myocardial infarction in rats. The possible mechanisms may be related to its resistance to oxidative stress, and up-regulation of Bcl-2 protein expression and down-regulation of Bax protein expression in myocardial tissue.

The effects of inhaled NO on plasma vasoactive factor and CTnI level in rabbits with acute massive pulmonary embolism

Abstract Purpose: To investigate changes in the plasma concentrations of cardiac troponin I (CTnI), thromboxane A2 (TXA2), prostaglandin I2 (PGI2) and endothelin-1 (ET-1) in rabbits with massive pulmonary embolism (AMPE) and the impact of nitric oxide inhalation (NOI) on these indices. Methods: A total of 30 Japanese rabbits were used to construct an MPE model and were divided into 3 groups equally (n=10), including an EXP group (undergoing modeling alone), an NOI group (receiving NOI 2 h post-modeling) and a CON group (receiving intravenous physiological saline). Results: In the model group, plasma concentration of CTnI peaked at 16 h following modeling (0.46±0.10 µg/ml) and significantly decreased following NOI. Plasma levels of TXB2, PGI2 and ET-1 peaked at 12, 16 and 8 h following modeling, respectively, and significantly decreased at different time points (0, 2, 4, 8, 12, 16, 20 and 24 h) following NOI. A significant correlation was observed between the peak plasma CTnI concentration and peak TXB2, 6-keto prostaglandin F1α and ET-1 concentrations in the model and NOI groups. Conclusion: Increases in plasma TXA2, PGI2 and ET-1 levels causes myocardial damage in a rabbit model of AMPE; however, NOI effectively down regulates the plasma concentration of these molecules to produce a myocardial-protective effect.

The effects of inhaled NO on plasma vasoactive factor and CTnI level in rabbits with acute massive pulmonary embolism

Purpose: To investigate changes in the plasma concentrations of cardiac troponin I (CTnI), thromboxane A2 (TXA2), prostaglandin I2 (PGI2) and endothelin-1 (ET-1) in rabbits with massive pulmonary embolism (AMPE) and the impact of nitric oxide inhalation (NOI) on these indices. Methods: A total of 30 Japanese rabbits were used to construct an MPE model and were divided into 3 groups equally (n=10), including an EXP group (undergoing modeling alone), an NOI group (receiving NOI 2 h post-modeling) and a CON group (receiving intravenous physiological saline). Results: In the model group, plasma concentration of CTnI peaked at 16 h following modeling (0.46±0.10 µg/ml) and significantly decreased following NOI. Plasma levels of TXB2, PGI2 and ET-1 peaked at 12, 16 and 8 h following modeling, respectively, and significantly decreased at different time points (0, 2, 4, 8, 12, 16, 20 and 24 h) following NOI. A significant correlation was observed between the peak plasma CTnI concentration and peak TXB2, 6-keto prostaglandin F1 and ET-1 concentrations in the model and NOI groups. Conclusion: Increases in plasma TXA2, PGI2 and ET-1 levels causes myocardial damage in a rabbit model of AMPE; however, NOI effectively down regulates the plasma concentration of these molecules to produce a myocardial-protective effect.(AU)

Increased Levels of Txa2 Induced by Dengue Virus Infection in IgM Positive Individuals Is Related to the Mild Symptoms of Dengue.

The inflammatory process plays a major role in the prognosis of dengue. In this context, the eicosanoids may have considerable influence on the regulation of the Dengue virus-induced inflammatory process. To quantify the molecules involved in the cyclooxygenase and lipoxygenase pathways during Dengue virus infection, plasma levels of thromboxane A2, prostaglandin E2 and leukotriene B4; mRNA levels of thromboxane A2 synthase, prostaglandin E2 synthase, leukotriene A4 hydrolase, cyclooxygenase-2 and 5-lipoxygenase; and the levels of lipid bodies in peripheral blood leukocytes collected from IgM-positive and IgM-negative volunteers with mild dengue, and non-infected volunteers, were evaluated. Dengue virus infection increases the levels of thromboxane A2 in IgM-positive individuals as well as the amount of lipid bodies in monocytes in IgM-negative individuals. We suggest that increased levels of thromboxane A2 in IgM-positive individuals plays a protective role against the development of severe symptoms of dengue, such as vascular leakage.

Protective effect of dexmedetomidine against myocardial ischemia-reperfusion injury in rabbits.

PURPOSE: To investigate the influence of dexmedetomidine on myocardial ischemia-reperfusion injury (IRI) in rabbits. METHODS: Twenty-four New Zealand white rabbits were randomly divided into two equal-sized groups: IRI group (group IR) and dexmedetomidine group (group D). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), left ventricular diastolic pressure (LVDP), +dp/dtmax, -dp/dtmax, and t-dp/dtmax were recorded and calculated at the following time points: before (T0) and after (T1) dexmedetomidine infusion, after 30-min ischemia (T2), and after 120-min reperfusion (T3). The levels of plasma endothelin 1 (ET-1), thromboxane A2 (TXA2), and platelet activating factor (PAF); area of myocardial infarction (MI); and no-reflow area were evaluated. RESULTS: SBP, DBP, LVSP, LVEDP, LVDP, and +dp/dtmax at T3 were higher in group D than in group IR (P<0.05). The average no-reflow area in group IR was significantly smaller than that in group D (14±3% vs. 38±5%, P=0.0116). The ET-1, TXA2, and PAF levels at T2 and T3 were higher than those at T0 in both groups (P<0.05). CONCLUSION: Dexmedetomidine could reduce the magnitude of ischemic myocardial no-reflow area and protect the myocardium with ischemia-reperfusion injury.

Protective effect of dexmedetomidine against myocardial ischemia-reperfusion injury in rabbits

Abstract Purpose: To investigate the influence of dexmedetomidine on myocardial ischemia-reperfusion injury (IRI) in rabbits. Methods: Twenty-four New Zealand white rabbits were randomly divided into two equal-sized groups: IRI group (group IR) and dexmedetomidine group (group D). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), left ventricular diastolic pressure (LVDP), +dp/dtmax, -dp/dtmax, and t-dp/dtmax were recorded and calculated at the following time points: before (T0) and after (T1) dexmedetomidine infusion, after 30-min ischemia (T2), and after 120-min reperfusion (T3). The levels of plasma endothelin 1 (ET-1), thromboxane A2 (TXA2), and platelet activating factor (PAF); area of myocardial infarction (MI); and no-reflow area were evaluated. Results: SBP, DBP, LVSP, LVEDP, LVDP, and +dp/dtmax at T3 were higher in group D than in group IR (P<0.05). The average no-reflow area in group IR was significantly smaller than that in group D (14±3% vs. 38±5%, P=0.0116). The ET-1, TXA2, and PAF levels at T2 and T3 were higher than those at T0 in both groups (P<0.05). Conclusion: Dexmedetomidine could reduce the magnitude of ischemic myocardial no-reflow area and protect the myocardium with ischemia-reperfusion injury.

Sildenafil (Viagra®) Prevents Cox-1/ TXA2 Pathway-Mediated Vascular Hypercontractility in ApoE-/- Mice.

BACKGROUND/AIMS: The atherosclerotic apolipoprotein E-deficient (apoE-/-) mouse exhibits impaired vasodilation and enhanced vasoconstriction responsiveness. The objectives of this study were: a) to determine the relative contribution of cyclooxygenases (Cox-1 and Cox-2), thromboxane A2 (TXA2) and endothelin-1 (ET-1) to enhancing vascular hyperresponsiveness in this model of atherosclerosis and b) to investigate the beneficial effects of the phosphodiesterase 5 inhibitor sildenafil on this endothelial dysfunction. METHODS: Adult male apoE-/- mice were treated with sildenafil (40 mg/kg/day, for 3 weeks) and compared with non-treated ApoE-/- and wild-type mice. The beneficial effects of sildenafil on vascular contractile response to phenylephrine (PE) in aortic rings were evaluated before and after incubation with Cox-1 (SC-560) or Cox-2 (NS-398) inhibitors or the TP antagonist SQ-29548, and on contractile responsiveness to ET-1. RESULTS: ApoE-/- mice exhibited enhanced vasoconstriction to PE (Rmax ∼35%, p<0.01), which was prevented by treatment with sildenafil. The enhanced PE-induced contractions were abolished by both Cox-1 inhibition and TP antagonist, but were not modified by Cox-2 inhibition. Aortic rings from ApoE-/- mice also exhibited enhanced contractions to ET-1 (Rmax ∼30%, p<0.01), which were attenuated in sildenafil-treated ApoE-/- mice. In addition, we observed augmented levels of vascular proinflammatory cytokines in ApoE-/- mice, which were partially corrected by treatment with sildenafil (IL-6, IL-10/IL-6 ratio and MCP-1). CONCLUSION: The present data show that the Cox-1/TXA2 pathway prevails over the Cox-2 isoform in the mediation of vascular hypercontractility observed in apoE-/-mice. The results also show a beneficial effect of sildenafil on this endothelial dysfunction and on the proinflammatory cytokines in atherosclerotic animals, opening new perspectives for the treatment of other endothelium-related cardiovascular abnormalities.

Endothelial nitric oxide synthase and cyclooxygenase are activated by hydrogen peroxide in renal hypertensive rat aorta.

In this work, we hypothesized that cyclooxygenase (COX) activity can be regulated by nitric oxide (NO) and hydrogen peroxide (H2O2). In the renal hypertension (2K-1C), phenylephrine (PE)-induced contraction was lower than in normotensive (2K) rat aortas. This impaired contraction is due to NO/H2O2- induced vasodilation. We evaluated the effects of H2O2 on the activity of COX and endothelial NO-Synthase (eNOS) in 2K-1C rat aortas stimulated with PE. Responses for PE or H2O2 were evaluated in 2K-1C and 2K rat aortas, without or with inhibitors for COX (Indomethacin) or eNOS (L-NAME). COX isoforms expression was evaluated by Western blotting. eNOS inhibition was tested on thromboxane A2 (TXA2) and prostacyclin (PGI2) production. PE-induced contraction was lower in 2K-1C than in 2K. Indomethacin reduced PE-induced contraction in 2K, but it had no effect in 2K-1C. L-NAME reversed indomethacin-induced effect in 2K and it normalized PE-induced contraction in 2K-1C to the normotensive levels. COX-1 and COX-2 expression, TXA2 and PGI2 production were higher in 2K-1C than in 2K. eNOS inhibition did no modify TXA2/PGI2 production. In low concentrations, H2O2 induced relaxation only in 2K that was abolished by L-NAME while the contractions induced by high concentrations were abolished by indomethacin in both 2K and 2K-1C. The activity/expression of COX, and TXA2/PGI2 production were increased in 2K-1C, which were not modified by eNOS. High levels of H2O2 increased the endothelial COX activity, which induced contraction. Therefore, an high increase in H2O2 production may increase COX-induced vasoconstriction rather than eNOS-induced relaxation, which might contribute to aggravate hypertension.

Ask1 regulates murine platelet granule secretion, thromboxane A2 generation, and thrombus formation.

Mitogen-activated protein kinases (MAPKs) are expressed in platelets and are activated downstream of physiological agonists. Pharmacological and genetic evidence indicate that MAPKs play a significant role in hemostasis and thrombosis, but it is not well understood how MAPKs are activated upon platelet stimulation. Here, we show that apoptosis signal-regulating kinase 1 (ASK1), a member of the MAP3K family, is expressed in both human and murine platelets. ASK1 is rapidly and robustly activated upon platelet stimulation by physiological agonists. Disruption of Ask1 (Ask1-/- ) resulted in a marked functional defect in platelets. Ask1-/- platelets showed an impaired agonist-induced integrin αIIbß3 activation and platelet aggregation. Although there was no difference in Ca2+ rise, platelet granule secretion and thromboxane A2 (TxA2) generation were significantly attenuated in Ask1-/- platelets. The defective granule secretion observed in Ask1-/- platelets was a consequence of impaired TxA2 generation. Biochemical studies showed that platelet agonists failed to activate p38 MAPK in Ask1-/- platelets. On the contrary, activation of c-Jun N-terminal kinases and extracellular signal-regulated kinase 1/2 MAPKs was augmented in Ask1-/- platelets. The defect in p38 MAPK results in failed phosphorylation of cPLA2 in Ask1-/- platelets and impaired platelet aggregate formation under flow. The absence of Ask1 renders mice defective in hemostasis as assessed by prolonged tail-bleeding times. Deletion of Ask1 also reduces thrombosis as assessed by delayed vessel occlusion of carotid artery after FeCl3-induced injury and protects against collagen/epinephrine-induced pulmonary thromboembolism. These results suggest that the platelet Ask1 plays an important role in regulation of hemostasis and thrombosis.

Salivary Thromboxane A2-Binding Proteins from Triatomine Vectors of Chagas Disease Inhibit Platelet-Mediated Neutrophil Extracellular Traps (NETs) Formation and Arterial Thrombosis.

BACKGROUND: The saliva of blood-feeding arthropods contains a notable diversity of molecules that target the hemostatic and immune systems of the host. Dipetalodipin and triplatin are triatomine salivary proteins that exhibit high affinity binding to prostanoids, such as TXA2, thus resulting in potent inhibitory effect on platelet aggregation in vitro. It was recently demonstrated that platelet-derived TXA2 mediates the formation of neutrophil extracellular traps (NETs), a newly recognized link between inflammation and thrombosis that promote thrombus growth and stability. METHODOLOGY/PRINCIPAL FINDINGS: This study evaluated the ability of dipetalodipin and triplatin to block NETs formation in vitro. We also investigated the in vivo antithrombotic activity of TXA2 binding proteins by employing two murine models of experimental thrombosis. Remarkably, we observed that both inhibitors abolished the platelet-mediated formation of NETs in vitro. Dipetalodipin and triplatin significantly increased carotid artery occlusion time in a FeCl3-induced injury model. Treatment with TXA2-binding proteins also protected mice from lethal pulmonary thromboembolism evoked by the intravenous injection of collagen and epinephrine. Effective antithrombotic doses of dipetalodipin and triplatin did not increase blood loss, which was estimated using the tail transection method. CONCLUSIONS/SIGNIFICANCE: Salivary TXA2-binding proteins, dipetalodipin and triplatin, are capable to prevent platelet-mediated NETs formation in vitro. This ability may contribute to the antithrombotic effects in vivo. Notably, both molecules inhibit arterial thrombosis without promoting excessive bleeding. Our results provide new insight into the antihemostatic effects of TXA2-binding proteins and may have important significance in elucidating the mechanisms of saliva to avoid host's hemostatic responses and innate immune system.

Daño a células endoteliales en cultivo inducido por el isoprostano 8-iso-PGF2a / Damage to cultured endothelial cells induced by isoprostane 8-iso PGF2

INTRODUCCIÓN: el endotelio vascular posee un papel esencial en los procesos asociados a la enfermedad cardiovascular. Existe estrecha relación entre el desbalance redox de estas células y la aparición y evolución de estas enfermedades. Entre los marcadores de daño oxidativo a los lípidos de membranas se encuentra el isoprostano 8-iso-PGF2a, que aumenta en estos pacientes. OBJETIVO: evaluar el efecto del isoprostano 8-iso-PGF2a sobre células endoteliales en cultivo y la protección con la proteína de estrés térmico a-cristalina. MÉTODOS: se cultivaron células endoteliales de la línea H5V y se evaluó el efecto del isoprostano 8-iso-PGF2a y del análogo del tromboxano A2, U46619, sobre la supervivencia celular. Se evaluó el efecto protector de la proteína de estrés térmico a-cristalina a través de la incubación de los cultivos con 1 mg/ml de la proteína previo a la inducción del daño con los compuestos en estudio. RESULTADOS: la supervivencia celular disminuyó proporcional al aumento de la concentración del isoprostano y del U46619. La a-cristalina aumentó la supervivencia celular en un 20 % al preincubar los cultivos sometidos al efecto de ambos compuestos. CONCLUSIONES: el isoprostano 8-iso-PGF2a, además, de ser un marcador de daño oxidativo puede ser considerado un inductor directo de daño a las células del endotelio vascular, efecto mediado a través, de la generación de tromboxano A2 o la activación de su receptor. La proteína de estrés térmico a-cristalina, añadida de forma exógena, puede considerarse un protector endotelial.

INTRODUCTION: the vascular endothelium plays an essential role in processes associated with cardiovascular disease. There is a close relationship between redox imbalance in these cells and the appearance and evolution of such diseases. Increased isoprostane 8-iso PGF2 is among the markers of oxidative damage to membrane lipids in these patients. OBJECTIVE: evaluate the effect of isoprostane 8-iso PGF2 on cultured endothelial cells and the protection provided by -crystallin heat-shock stress protein. METHODS: endothelial cells from line H5V were cultured to evaluate the effect of isoprostane 8-iso PGF2 and thromboxane A2 analog U46619 on cell survival. An evaluation was conducted of the protective effect of -crystallin heat-shock stress protein by incubation of the cultures with 1 mg/ml of the protein prior to damage induction with the study compounds. RESULTS: cell survival decreased as isoprostane and U46619 concentration increased. -Crystallin increased cell survival by 20% upon preincubation of the cultures subjected to both compounds. CONCLUSIONS: besides being an oxidative damage marker, isoprostane 8-iso PGF2 may be considered a direct inducer of damage to vascular endothelial cells. This effect is mediated by the generation of thromboxane A2 or the activation of its receptor. Added exogenously, -crystallin heat-shock stress protein may be considered to be an endothelial protector.

Interrelación del equilibrio tromboxano A2-prostaciclina y su modificación cuando se ingiere aspirina / Interrelation of the balance tromboxano A2-prostaciclina and its modification when aspirin is ingested

Introducción: la aspirina, es usada por su acción antiinflamatoria, analgésica, antipirética y antiagregante plaquetaria. El conocimiento del metabolismo del ácido araquidónico es fundamental para el estomatólogo que basa su trabajo en diagnosticar y tratar procesos inflamatorios en tejidos bucodentales, también por su condición de cirujano debe estar alerta en no realizar intervenciones quirúrgicas en pacientes que estén tomando aspirina, por interrumpir este medicamento la agregación plaquetaria, importante paso de la hemostasia normal. Objetivo: interpretar la interrelación hemostática del tromboxano A2 y la prostaciclina en condiciones fisiológicas, y el resultado de su modificación cuando se ingiere aspirina. Método: PubMed fue empleada como fundamental fuente de búsqueda, que incluyó el conocimiento sobre el fármaco aspirina, la interacción del tromboxano y la prostaclina, y la acción que sobre el equilibrio de estos productos ejerce la aspirina; también se revisaron HINARI, LILACS y Medline. Desarrollo: el ácido araquidónico es un ácido graso poliinsaturado de 20 átomos de carbono (ácido 5, 8, 11, 14-eicosatetraenoico) que procede directamente de la dieta. La relación recíproca entre PG-I2 y el TxA2 constituye un mecanismo finamente equilibrado que sirve para regular la función plaquetaria del ser humano. La utilidad de la aspirina en los pacientes expuestos a trombogénesis se debe, en gran parte, a su capacidad para inhibir la síntesis del TxA2, agente derivado del ácido araquidónico, elemento que se encuentra esterificado a los fosfolípidos de la membrana plaquetaria. El óxido nítrico, igual que la PG-I2, actúa también como vasodilatador e inhibidor de la agregación plaquetaria. Conclusiones: los pacientes que acuden al estomatólogo y por prescripción facultativa están tomando aspirina, tienen su sistema plaquetario inhibido y no pueden sintetizar tromboxano. El proceder quirúrgico por parte del estomatólogo en un paciente que esté ingiriendo aspirina lo expone al desarrollo de hemorragia de causa iatrogénica(AU)

Introduction: aspirin is used by its arachidonic acid is fundamental for the dentist that bases its work on diagnosis and treatment of inflammatory processes, also for its surgeon condition he should be alert to do not carry out surgical interventions in patients that are taking aspirin, because this drug interrupts platelet aggregation, important step of the normal hemostasis. Objective: to interpret the hemostatic interrelation of the tromboxano A2 and the prostaciclina in physiologic conditions and the result of their modification when aspirin is ingested. Method: it was employee as fundamental search source the PubMed, other databases also revised they were HINARI, LILACS, Medline. Was carried out a search that included the knowledge on the drug aspirin, the interaction of the tromboxano and the prostaclina, and the action that it has more than enough the balance of these products it exercises the aspirin. Development: the arachidonic acid is a polyunsaturated fatty acid of 20 atoms of carbon (5, 8, 11, 14-eicosatetraenoic acid) that proceeds directly from diet. The reciprocal relationship between PG-I2 and TxA2 constitutes a finely balanced mechanism that is good to regulate the human being's platelet function. The utility of aspirin in patients exposed to thrombogenesis is largely due to its capacity to inhibit the synthesis of the TxA2, agent derived from arachidonic acid, which is esterified to the phospholipids of the platelet membrane. Nitric oxide, the same as the PG-I 2, also acts as vasodilator and inhibitor of the platelet aggregation. Conclusions: the patients that go to the dentist and for medical prescription are taking aspirin, have their platelet system inhibited and cannot synthesize tromboxane. Surgical processes performed by the dentist in a patient that is ingesting aspirin exposes him to the development of hemorrhage of yatrogenic cause(AU)

Galectins in the regulation of platelet biology.

Platelets are anucleated blood cells derived from megakaryocytes, and although they are essential for proper hemostasis, their function extends to physiologic processes such as tissue repair, wound remodeling, and antimicrobial host defense, or pathologic conditions such as thrombosis, atherosclerosis, chronic inflammatory diseases, and cancer. Recently, we demonstrated that two structurally divergent members of the galectin family, galectin-1 and galectin-8, are potent platelet agonists. The emergence of galectins as soluble mediators capable of triggering platelet activation opens a new field of research that will provide further insights into the mechanisms linking inflammatory responses to thrombus formation and could expand our view of the role of platelets much beyond hemostasis to their pathophysiologic role during inflammation and cancer. The present article details the various protocols and reagents currently used in our laboratory to study the role of galectins in human platelet function.

Protection of vascular endothelium by aspirin in a murine model of chronic Chagas' disease.

Chronic Chagas' disease affects 10-30 % of patients infected with Trypanosoma cruzi, and it mainly manifests as cardiomyopathy. Important pathophysiological mechanisms involved in the cardiac lesions include activation of the endothelium and induced microvascular alterations. These processes involve the production of endothelial adhesion molecules and thromboxane A2, which are involved in inflammatory cell recruitment and platelet aggregation, respectively. Cyclooxygenase inhibitors such as aspirin decrease thromboxane production and alter the course of Chagas' disease, both in the acute and chronic phases. We studied the effects of the administration of low and high doses of aspirin during the early phase of T. cruzi infection, following microvascular damage in the context of a chronic murine model of Chagas' disease. The effects of both schedules were assessed at 24 and 90 days postinfection by evaluating parasitemia, mortality, and cardiac histopathological changes as well as the expression of ICAM, VCAM, and E-selectin in cardiac tissue. Thromboxane A2, soluble ICAM, and E-selectin blood levels were also measured. While aspirin did not affect parasitemia or mortality in the infected mice, it decreased both cardiac inflammatory infiltrates and thromboxane levels. Additionally, at 90 days postinfection, aspirin normalized sICAM and sE-selectin levels. Considering the improved endothelial function induced by aspirin, we propose the possibility of including this drug in clinical therapy to treat chronic Chagas' disease.

Histamine, carbachol, and serotonin induce hyperresponsiveness to ATP in guinea pig tracheas: involvement of COX-2 pathway.

Extracellular ATP promotes an indirect contraction of airway smooth muscle via the secondary release of thromboxane A2 (TXA2) from airway epithelium. Our aim was to evaluate if common contractile agonists modify this response to ATP. Tracheas from sensitized guinea pigs were used to evaluate ATP-induced contractions before and after a transient contraction produced by histamine, carbachol, or serotonin. Epithelial mRNA for COX-1 and COX-2 was measured by RT-PCR and their expression assessed by immunohistochemistry. Compared with the initial response, ATP-induced contraction was potentiated by pretreatment with histamine, carbachol, or serotonin. Either suramin (antagonist of P2X and P2Y receptors) plus RB2 (antagonist of P2Y receptors) or indomethacin (inhibitor of COX-1 and COX-2) annulled the ATP-induced contraction, suggesting that it was mediated by P2Y receptor stimulation and TXA2 production. When COX-2 was inhibited by SC-58125 or thromboxane receptors were antagonized by SQ-29548, just the potentiation was abolished, leaving the basal response intact. Airway epithelial cells showed increased COX-2 mRNA after stimulation with histamine or carbachol, but not serotonin, while COX-1 mRNA was unaffected. Immunochemistry corroborated this upregulation of COX-2. In conclusion, we showed for the first time that histamine and carbachol cause hyperresponsiveness to ATP by upregulating COX-2 in airway epithelium, which likely increases TXA2 production. Serotonin-mediated hyperresponsiveness seems to be independent of COX-2 upregulation, but nonetheless is TXA2 dependent. Because acetylcholine, histamine, and serotonin can be present during asthmatic exacerbations, their potential interactions with ATP might be relevant in its pathophysiology.

Increased cyclooxygenase-2-derived prostanoids contributes to the hyperreactivity to noradrenaline in mesenteric resistance arteries from offspring of diabetic rats.

This study analyzed the effect of in utero exposure to maternal diabetes on contraction to noradrenaline in mesenteric resistance arteries (MRA) from adult offspring, focusing on the role of cyclooxygenase (COX)-derived prostanoids. Diabetes in the maternal rat was induced by a single injection of streptozotocin (50 mg/kg body weight) on day 7 of pregnancy. Contraction to noradrenaline was analyzed in isolated MRA from offspring of diabetic (O-DR) and non-diabetic (O-CR) rats at 3, 6 and 12 months of age. Release of thromboxane A(2) (TxA(2)) and prostaglandins E(2) (PGE(2)) and F(2α) (PGF(2α)), was measured by specific enzyme immunoassay kits. O-DR developed hypertension from 6 months of age compared with O-CR. Arteries from O-DR were hyperactive to noradrenaline only at 6 and 12 months of age. Endothelial removal abolished this hyperreactivity to noradrenaline between O-CR and O-DR. Preincubation with either the COX-1/2 (indomethacin) or COX-2 inhibitor (NS-398) decreased noradrenaline contraction only in 6- and 12-month-old O-DR, while it remained unmodified by COX-1 inhibitor SC-560. In vessels from 6-month-old O-DR, a similar reduction in the contraction to noradrenaline produced by NS-398 was observed when TP and EP receptors were blocked (SQ29548+AH6809). In 12-month-old O-DR, this effect was only achieved when TP, EP and FP were blocked (SQ29548+AH6809+AL8810). Noradrenaline-stimulated TxB(2) and PGE(2) release was higher in 6- and 12-month-old O-DR, whereas PGF(2α) was increased only in 12-month-old O-DR. Our results demonstrated that in utero exposure to maternal hyperglycaemia in rats increases the participation of COX-2-derived prostanoids on contraction to noradrenaline, which might help to explain the greater response to this agonist in MRA from 6- and 12-month-old offspring. As increased contractile response in resistance vessels may contribute to hypertension, our results suggest a role for these COX-2-derived prostanoids in elevating vascular resistance and blood pressure in offspring of diabetic rats.

Toll-like receptor 4 contributes to blood pressure regulation and vascular contraction in spontaneously hypertensive rats.

Activation of TLRs (Toll-like receptors) induces gene expression of proteins involved in the immune system response. TLR4 has been implicated in the development and progression of CVDs (cardio-vascular diseases). Innate and adaptive immunity contribute to hypertension-associated end-organ damage, although the mechanism by which this occurs remains unclear. In the present study, we hypothesize that inhibition of TLR4 decreases BP (blood pressure) and improves vascular contractility in resistance arteries from SHR (spontaneously hypertensive rats). TLR4 protein expression in mesenteric resistance arteries was higher in 15-week-old SHR than in age-matched Wistar controls or in 5-week-old SHR. To decrease the activation of TLR4, 15-week-old SHR and Wistar rats were treated with anti-TLR4 (anti-TLR4 antibody) or non-specific IgG control antibody for 15 days (1 µg per day, intraperitoneal). Treatment with anti-TLR4 decreased MAP (mean arterial pressure) as well as TLR4 protein expression in mesenteric resistance arteries and IL-6 (interleukin 6) serum levels from SHR when compared with SHR treated with IgG. No changes in these parameters were found in treated Wistar control rats. Mesenteric resistance arteries from anti-TLR4-treated SHR exhibited decreased maximal contractile response to NA (noradrenaline) compared with IgG-treated SHR. Inhibition of COX (cyclo-oxygenase)-1 and COX-2, enzymes related to inflammatory pathways, decreased NA responses only in mesenteric resistance arteries of SHR treated with IgG. COX-2 expression and TXA2 (thromboxane A2) release were decreased in SHR treated with anti-TLR4 compared with IgG-treated SHR. Our results suggest that TLR4 activation contributes to increased BP, low-grade inflammation and plays a role in the augmented vascular contractility displayed by SHR.