RESUMEN
BACKGROUND: Forelimb Asymmetry Test is a simple test of motor function, using exploration behavior of a rat in a novel environment and counting the number of times that a rat touches the wall with either forepaw. Our lab has noticed, however, that there appears to be an increased number of fingertip touches to the wall following a stroke in the impaired forelimb. NEW METHOD: We counted the number of times that the animal either laid its palm flat against the wall of the chamber or touched the wall with only its fingertips, for both the left and right forepaws. We also separated bouts of exploration, so we could clearly determine if fingertip touches normally were associated with a transition from resting state to exploration state. RESULTS AND COMPARISON WITH EXISTING METHODS: Fishers exact test indicated that there were significant differences in the way that the animals touched the wall pre-stroke compared to post-stroke, with more fingertip touches occurring post-stroke. Counting palm touches as normal and fingertip touches as abnormal increases the sensitivity of the Forelimb Asymmetry analysis and gives a good correlation with the contralateral functional deficits determined by Montoya Staircase post-stroke. If we counted every wall touch as normal (palm touches and fingertip touches), we see a loss of sensitivity and a poor correlation with contralateral function as determined by Montoya Staircase. CONCLUSIONS: This refinement of the Forelimb Asymmetry analysis improves correlation with Montoya Staircase contralateral function after stroke.
Asunto(s)
Miembro Anterior/fisiopatología , Lateralidad Funcional/fisiología , Desempeño Psicomotor/fisiología , Accidente Cerebrovascular/patología , Accidente Cerebrovascular/fisiopatología , Animales , Modelos Animales de Enfermedad , Endotelinas/toxicidad , Conducta Exploratoria/fisiología , Femenino , Ratas , Ratas Sprague-Dawley , Estadística como Asunto , Accidente Cerebrovascular/inducido químicamente , Rehabilitación de Accidente Cerebrovascular , Factores de TiempoRESUMEN
The aim of the study was to evaluate the clinical efficacy of hydrogen sulfide (H2S) treatment on the endothelin-induced cardiac hypertrophy. Sixty-four adult male rats, weighing from 180 to 200 g, were randomly divided into four groups: ten in normal group, ten in sham group, 44 in model group established by inducing the myocardial hypertrophy with endothelin. The myocardial hypertrophy model rats were randomly divided into two groups: 22 in the simple myocardial hypertrophy model group and 22 in the H2S treatment group. Rats in normal group were given 2 ml pure water by gavage per day, those in the sham group and simple cardiac hypertrophy model group were given 2 ml of saline by gavage per day, and rats in the pure cardiac hypertrophy with H2S treatment were given intraperitoneal injections of 2 ml NaHS saline per day for a period of 4 weeks. Left ventricular mass index, myocyte hypertrophy, volume fraction of myocardial interstitial collagen, myocardial hydroxyproline content and other indicators of cardiac hypertrophy were observed after 4 weeks. (1) There were significant differences on the ventricular mass between the treatment group and the cardiac hypertrophy group: The left ventricular mass decreased 21.4 % and the left ventricular mass index decreased 5.97 % (P < 0.05; (2) the smallest cardiomyocytes diameter and cardiomyocytes cross-sectional area decreased 12.5 and 10.8 %, respectively (P < 0.05) in the treatment group compared to the cardiac hypertrophy group; (3) the volume fraction of myocardial interstitial collagen and the myocardial hydroxyproline content decreased 22.3 and 31.3 % in treatment group compared with the cardiac hypertrophy group, respectively (P < 0.05). H2S had a good clinical efficacy in reducing left ventricular mass fraction and myocardial collagen levels, improving myocardial hypertrophy and decrease myocardial fibrosis. It is worthy for further clinical studies.
Asunto(s)
Cardiomegalia/tratamiento farmacológico , Sulfuro de Hidrógeno/uso terapéutico , Miocardio/metabolismo , Animales , Cardiomegalia/inducido químicamente , Cardiomegalia/metabolismo , Colágeno/metabolismo , Modelos Animales de Enfermedad , Endotelinas/toxicidad , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Sulfuro de Hidrógeno/farmacología , Masculino , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Tamaño de los Órganos/efectos de los fármacos , Ratas , Ratas Sprague-DawleyRESUMEN
We investigated the effects of a neurorestorative treatment paradigm using long-term, central delivery of growth hormone (GH) starting 4 days after stroke. It has been shown previously that a neural GH axis is activated after stroke, that GH is neuroprotective, and can have direct trophic actions on neurons and stem cells. First, we developed and validated a buffer that kept rat GH bioactive for 2 weeks at body temperature. Implanted minipumps were used to chronically infuse GH into the lateral ventricle of unilateral stroke injured adult rats. Initially, a dose ranging pilot study was used to characterize the neuroendocrine effects and distribution of the infused GH. Next, a 6-week treatment trial starting 4 days after induction of the stroke was performed and the animals allowed to recover for a further 6 weeks. Behavioural and endocrinological measures were taken. We found that the infused GH localized to cells within the ipsilateral; subventricular zone, white matter tract, lesion and penumbral regions. GH treatment accelerated recovery of one out of three tests of motor function (P<0.001) and improved spatial memory on the Morris water maze test at the end of the study (P<0.05), with no effect on learning. We also found that GH treatment was associated with a reversible increase in body weight (P<0.01) whilst circulating IGF-1 (insulin-like growth factor 1) levels were halved (P<0.001). Delayed and chronic treatment of stroke with central GH may accelerate some aspects of functional recovery and improve spatial memory in the long-term.
Asunto(s)
Hormona del Crecimiento/uso terapéutico , Accidente Cerebrovascular/tratamiento farmacológico , Animales , Encéfalo/efectos de los fármacos , Encéfalo/patología , Tampones (Química) , Cateterismo , Corticosterona/sangre , Corticosterona/metabolismo , Endotelinas/toxicidad , Hormona del Crecimiento/administración & dosificación , Factor I del Crecimiento Similar a la Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/uso terapéutico , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Trastornos de la Memoria/tratamiento farmacológico , Proyectos Piloto , Ratas , Ratas Sprague-Dawley , Recuperación de la Función/efectos de los fármacos , Índice de Severidad de la Enfermedad , Percepción Espacial/efectos de los fármacos , Accidente Cerebrovascular/inducido químicamente , Accidente Cerebrovascular/patología , Aumento de Peso/efectos de los fármacosRESUMEN
Sarafotoxins (SRTXs) constitute a family of vasoactive peptides that were initially isolated from the venom of Atractaspis engaddensis, and that are structurally and functionally related to endothelins (ETs). Analysis of the venom of Atractaspis microlepidota microlepidota revealed several new SRTX molecules manifesting some new structural and functional characteristics. These novel SRTXs are longer by three amino acids than the previously described SRTXs, and are designated here "long-SRTXs". Six isoforms, derived from new poly-cistronic precursors, have been identified so far in the venom of this snake. One of these isoforms, designated SRTX-m, was chemically synthesized and its biological properties were studied. Our results show that SRTX-m induces toxicity in mice, mostly due to vasoconstriction, and also that it has a lower toxicity and potency than the more potent SRTX described up to now: sarafotoxin-b (SRTX-b) from A. engaddensis.
Asunto(s)
Endotelinas/química , Péptidos/química , Venenos de Víboras/química , Secuencia de Aminoácidos , Animales , Relación Dosis-Respuesta a Droga , Endotelinas/toxicidad , Frecuencia Cardíaca/efectos de los fármacos , Ratones , Datos de Secuencia Molecular , Contracción Muscular/efectos de los fármacos , Péptidos/genética , Péptidos/toxicidad , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/toxicidad , Conejos , Serpientes , Vasoconstrictores/química , Vasoconstrictores/toxicidad , Venenos de Víboras/genética , Venenos de Víboras/toxicidadRESUMEN
In some disorders of the peripheral nervous system, it is relevant to understand how sensory neurons respond to selective ganglion ischemia. Sensory dorsal root ganglia may be susceptible to ischemic damage and irretrievable neuron loss because of their metabolic requirements. In diabetes, heightened sensitivity to ischemia associated with elevated endothelin levels might render ganglia particularly vulnerable. In this work, we created a model of local sensory ganglion ischemia by generating intense local vasoconstriction from applied endothelin-1 (ET). In this model, we compared relative vulnerability of L5 ganglia microvessels and neurons to ET in streptozotocin-induced diabetic rats and nondiabetic controls. Diabetic ganglia had reductions in baseline core ganglion blood flow (GBF) measured using microelectrode hydrogen clearance polarography and ET induced particularly profound declines. Serial GBF measurements made using a laser Doppler flowmetry probe also indicated that diabetic ganglia exposed to ET had a marked prolongation in its action. Neuron perikarya and proximal axon segments were more vulnerable in diabetes. Neurons exhibited loss of neurofilament labeling, dissolution of the neurons, replacement of neurons with "nests of Nageotte," displacement of nuclei to the periphery of perikarya, and nuclear labeling with TUNEL. Both intraganglionic axons and downstream sural sensory axons developed evidence of axonal degeneration. Local endothelin-induced vasoconstriction of microvessels supplying dorsal root ganglia provides a selective model of ischemia. Diabetic vessels and neurons, exposed to a greater depth and duration of ischemia from endothelin, are especially vulnerable.
Asunto(s)
Diabetes Mellitus Experimental/fisiopatología , Endotelinas/toxicidad , Ganglios Sensoriales/irrigación sanguínea , Ganglios Sensoriales/efectos de los fármacos , Isquemia/fisiopatología , Vasoconstricción/efectos de los fármacos , Animales , Diabetes Mellitus Experimental/patología , Ganglios Sensoriales/patología , Isquemia/patología , Masculino , Microcirculación/efectos de los fármacos , Microcirculación/patología , Neuronas/efectos de los fármacos , Neuronas/patología , Ratas , Ratas Sprague-Dawley , Vasoconstricción/fisiologíaRESUMEN
RATIONALE AND OBJECTIVES: The purpose of this research was to study the effects of the radiocontrast medium (CM) Hypaque-76 (diatrizoate meglumine sodium), equiosmolar mannitol, and endothelin on blood pressure and renal damage in a aging male spontaneously hypertensive rat, a small animal model for CM-induced renal damage. The importance of the pressor effect and the high osmolality of CM in producing renal damage was investigated by first reducing the blood pressure with pentobarbital anesthesia, which suppresses sympathetic nervous system activity, then testing the effects of CM, saline, mannitol, and the potent vasoconstrictor endothelin alone and in combination with CM. METHODS: Systolic blood pressure was measured in 14-month-old male rats (1) when awake, (2) after pentobarbital anesthesia, (3) after the administration of saline, CM, mannitol, endothelin, or CM plus endothelin, (4) after awakening the same day, and (5) the following day while awake. Renal damage was quantified by evaluating histopathologically the left kidney removed the day after administration of test substances. RESULTS: The pentobarbital-lowered blood pressure remained depressed after saline and mannitol but rose dramatically after CM, endothelin, and CM plus endothelin. Renal damage, compared with the saline controls, occurred with CM, mannitol, endothelin, and endothelin plus CM. The order of increasing severity was mannitol = CM < endothelin < endothelin plus CM. CONCLUSIONS: The effect of CM on systolic blood pressure is not related to its osmolality. High osmolality, however, appears to be a factor in CM-induced renal damage. Ischemia and direct nephrotoxicity are factors contributing to the renal-damaging effects of CM, mannitol, and endothelin.
Asunto(s)
Presión Sanguínea/efectos de los fármacos , Medios de Contraste/toxicidad , Diatrizoato de Meglumina/toxicidad , Diatrizoato/toxicidad , Diuréticos Osmóticos/toxicidad , Endotelinas/toxicidad , Enfermedades Renales/inducido químicamente , Manitol/toxicidad , Envejecimiento/efectos de los fármacos , Animales , Combinación de Medicamentos , Hipertensión/fisiopatología , Enfermedades Renales/patología , Masculino , Ratas , Ratas Endogámicas SHRRESUMEN
Treatment of animals with big endothelin-1 (bET) causes pulmonary hypertension and bronchoconstriction, both in vivo and in perfused lungs. The biological activity of bET requires proteolytic cleavage to ET-1 by endothelin converting enzymes (ECE) and possibly other proteases such as neutral endopeptidase 24.11 (NEP 24.11). Since the role of NEP 24.11 in the physiological activation of bET is unclear, we investigated the effects of the selective NEP 24.11 inhibitor thiorphan on bET-induced vaso- and bronchoconstriction in the isolated perfused rat lung. We also studied the effects of phosphoramidon and (S)-2-biphenyl-4-yl-1-(1H-tetraol-5-yl)-ehtylaminomethylphosphonic acid (CGS-26303), i.e. agents which block not only NEP 24.11 but also ECE. The bET-induced vasoconstriction was much less prominent than the bronchoconstriction, i.e. after exposure for 110 min vascular and airway conductance were decreased by 33% and 80% respectively. The small bET-induced vasoconstriction was attenuated to a similar degree by pretreatment with any of the three protease inhibitors. However, thiorphan up to a concentration of 10 microM had only little effect on the bET-induced bronchoconstriction, while 10 microM phosphoramidon or CGS-26303 provided half-maximal and 100 microM phosphoramidon complete protection in this model. This profile of inhibitor action suggests that in rat lung ECE is the major enzyme responsible for activation of bET.
Asunto(s)
Ácido Aspártico Endopeptidasas/metabolismo , Broncoconstricción/efectos de los fármacos , Endotelinas/toxicidad , Pulmón/efectos de los fármacos , Neprilisina/metabolismo , Precursores de Proteínas/toxicidad , Vasoconstricción/efectos de los fármacos , Resistencia de las Vías Respiratorias/efectos de los fármacos , Análisis de Varianza , Animales , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Endotelina-1 , Enzimas Convertidoras de Endotelina , Femenino , Glicopéptidos/farmacología , Pulmón/irrigación sanguínea , Pulmón/enzimología , Metaloendopeptidasas/antagonistas & inhibidores , Metaloendopeptidasas/metabolismo , Neprilisina/antagonistas & inhibidores , Organofosfonatos/farmacología , Perfusión , Inhibidores de Proteasas/farmacología , Ratas , Ratas Wistar , Tetrazoles/farmacología , Tiorfan/farmacología , Resistencia Vascular/efectos de los fármacosRESUMEN
Endothelins have potent biological effect in vivo which may, in part, be mediated by stimulation of cyclooxygenase metabolism of arachidonic acid. We administered endothelins (ETs) intravenously to chronically instrumented awake sheep with and without pretreatment with meclofenamate (n = 8). 30 micrograms doses of ET-1, ET-2, and ET-3 caused similar degrees of acute elevation of pulmonary artery pressure (PPA), reduction of the dynamic compliance of the lungs (Cdyn), and increases in lung lymph flow. Pretreatment with meclofenamate inhibited the rise in PPA and reduction in Cdyn, but had no effect on lung lymph flow. We conclude that the biological effects of the endothelins on PPA and Cdyn, but not lung fluid balance, are mediated in part by cyclooxygenase products of arachidonic acid metabolism.
Asunto(s)
Inhibidores de la Ciclooxigenasa/uso terapéutico , Endotelinas/toxicidad , Hipertensión Pulmonar/inducido químicamente , Pulmón/efectos de los fármacos , Ácido Meclofenámico/uso terapéutico , Animales , Presión Sanguínea , Endotelina-1/toxicidad , Endotelina-2/toxicidad , Endotelina-3/toxicidad , Femenino , Hipertensión Pulmonar/fisiopatología , Pulmón/fisiopatología , Rendimiento Pulmonar , Linfa/fisiología , Masculino , OvinosRESUMEN
A novel class of endothelin-A receptor ligands was discovered by high-throughput screening. Lead structure optimization led to highly potent antagonists which can be synthesized in a short sequence. The compounds are endothelin-A-selective, are orally available, and show a long duration of action.
Asunto(s)
Antagonistas de los Receptores de Endotelina , Endotelinas/toxicidad , Pirimidinas/síntesis química , Administración Oral , Animales , Compuestos de Dansilo/farmacología , Muerte Súbita , Diseño de Fármacos , Endotelinas/antagonistas & inhibidores , Humanos , Ligandos , Modelos Moleculares , Estructura Molecular , Pirimidinas/farmacología , Ratas , Receptor de Endotelina A , Receptores de Endotelina/metabolismo , Relación Estructura-Actividad , Sulfonamidas/farmacologíaRESUMEN
We tested the hypothesis that leukotoxin (Lx), a cytochrome P-450-dependent linoleate product of leukocytes, can stimulate the release of endothelin-1 (ET-1) from the lung and further that exogenous ET-1 synergizes with Lx to produce edematous lung injury. In isolated rat lungs perfused with Earle's balanced salt solution, Lx (10 mumol) alone caused lung edema and increased the perfusate and lung tissue ET-1 levels. The combination of ET-1 (5 nM) and Lx (5 mumol), at concentrations that by themselves did not increase wet lung weight, significantly increased wet lung weight, wet-to-dry lung weight ratio, as well as the lung effluent lactate dehydrogenase activity. Pretreatment with BQ-123 (5 x 10(-6) M), an endothelin A receptor antagonist that significantly attenuated the ET-1 (5 nM)-induced increase in pulmonary arterial pressure (Ppa) and pulmonary capillary pressure (Ppc), suppressed the edematous lung injury generated by the combination of ET-1 and Lx, suggesting that the edema-enhancing effect of ET-1 in Lx-treated lungs occurred through endothelin A receptor-dependent elevation of Ppa and Ppc. Elevation of the pulmonary venous pressure in Lx-treated lungs (13.5 cmH2O) mimicked the effect of ET-1 on Ppa and Ppc and produced a degree of lung edema that was comparable to that after combined ET-1 + Lx treatment but without increase in the perfusate lactate dehydrogenase. These data support the idea that ET-1 and Lx promote lung edema in a synergistic fashion.
Asunto(s)
Citotoxinas/toxicidad , Endotelinas/toxicidad , Exotoxinas/toxicidad , Edema Pulmonar/inducido químicamente , Animales , Presión Sanguínea/fisiología , Sinergismo Farmacológico , Antagonistas de los Receptores de Endotelina , Técnicas In Vitro , L-Lactato Deshidrogenasa/metabolismo , Pulmón/enzimología , Pulmón/fisiopatología , Masculino , Tamaño de los Órganos/fisiología , Péptidos Cíclicos/farmacología , Circulación Pulmonar/fisiología , Edema Pulmonar/patología , Edema Pulmonar/fisiopatología , Ratas , Ratas Sprague-Dawley , Receptores de Endotelina/metabolismo , Resistencia Vascular/efectos de los fármacosRESUMEN
1. Although recent observations suggest that endothelin-1 (ET-1) may play a role in the pathogenesis of asthma, to date little is known about the effects of ET-1 on parameters other than bronchoconstriction. The objectives of the present experiments were to study whether intravenously administered ET-1 could exert pro-inflammatory actions in the guinea-pig lung and to assess the involvement of endothelin ETA and ETB receptors in these events by using the ETA receptor-selective antagonist, FR 139317, the novel ETA/ETB receptor antagonist, bosentan and the ETB receptor-selective agonist, IRL 1620. 2. Bolus i.v. injection of ET-1 (0.1-1 nmol kg-1) to anaesthetized guinea-pigs evoked dose-dependent increases in mean arterial blood pressure which lasted for 6-12 min. This was accompanied by a dose-dependent haemoconcentration (8-15% plasma volume losses) and increases (up to 546%) in albumin extravasation in the trachea, upper and lower bronchi, but not in the pulmonary parenchyma. Qualitatively similar changes were observed following i.v. injection of the ETB receptor agonist, IRL 1620 (0.3 and 1 nmol kg-1), although IRL 1620 appeared to be about 3 times less potent than ET-1. The ETA receptor-selective antagonist, FR 139317 (2.5 mg kg-1) inhibited the ET-1 (1 nmol kg-1)-induced pressor response, haemoconcentration and albumin extravasation by 75, 77 and 60-70%, respectively, whereas it did not attenuate IRL 1620 (1 nmol kg-1)-induced changes. The ETA/ETB receptor antagonist, bosentan (10 mg kg-1) almost completely inhibited the pressor, haemoconcentration and permeability effects of both ET-1 and IRL 1620. 3. ET-1, but not IRL 1620 (0.1-1 nmol kg-1), produced a dose-dependent neutropenia with relative lymphocytosis and monocytosis, but did not induce influx of neutrophil granulocytes into pulmonary tissues or the bronchoalveolar space. ET-1 (1 nmol kg-1)-induced neutropenia was prevented by pretreatment of the animals with FR 139317 (2.5 mg kg-1), bosentan (10 mg kg-1) or adrenaline (90 nmol kg-1), indicating that ET-1 caused intravascular sequestration of neutrophil granulocytes. 4. ET-1 or IRL 1620 (10(-10)-10(-6) M) alone did not activate alveolar macrophages in vitro, whereas at a concentration of 10(-8) M, ET-1, but not IRL 1620, markedly potentiated superoxide production in response to f-Met-Leu-Phe (10(-9)-10(-7) M) and platelet-activating factor (PAF, 10(-9)-10(-7) M), but not to phorbol 12-myristate 13-acetate (10(-9) M). ET-1 did not affect f-Met-Leu-Phe- or PAF-induced increases in intracellular free calcium concentration. This potentiating effect of ET-1 was abolished by FR 139317(1.5 X 10-7 M).5. We conclude that, in addition to evoking airway contractions, ET-1 exerts pro-inflammatory actions via activation of the ETA and to a lesser extent the ETB receptors, and therefore, might contribute to the airway inflammation present in asthma. These findings also suggest the therapeutic potential of ETA/ETB receptor and perhaps ETA receptor-selective antagonists in this disease.
Asunto(s)
Endotelinas/toxicidad , Pulmón/efectos de los fármacos , Receptores de Endotelina/metabolismo , Animales , Azepinas/administración & dosificación , Azepinas/toxicidad , Presión Sanguínea/efectos de los fármacos , Bosentán , Secuestro Broncopulmonar/inducido químicamente , Permeabilidad Capilar/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Antagonistas de los Receptores de Endotelina , Endotelinas/administración & dosificación , Cobayas , Técnicas In Vitro , Indoles/administración & dosificación , Indoles/toxicidad , Inyecciones Intravenosas , Pulmón/metabolismo , Macrófagos Alveolares/efectos de los fármacos , Macrófagos Alveolares/patología , Masculino , N-Formilmetionina Leucil-Fenilalanina/análogos & derivados , N-Formilmetionina Leucil-Fenilalanina/toxicidad , Neutropenia/inducido químicamente , Neutrófilos/efectos de los fármacos , Neutrófilos/patología , Fragmentos de Péptidos/administración & dosificación , Fragmentos de Péptidos/toxicidad , Volumen Plasmático/efectos de los fármacos , Factor de Activación Plaquetaria/toxicidad , Receptor de Endotelina A , Receptor de Endotelina B , Sulfonamidas/administración & dosificación , Sulfonamidas/toxicidad , Superóxidos/metabolismo , Acetato de Tetradecanoilforbol/toxicidadRESUMEN
Local intra-arterial infusion of picomole quantities of endothelin-1 induced gastric vascular leakage of radiolabelled albumin. This leakage was partially inhibited by the platelet activating factor (PAF) receptor antagonist WEB 2086 (0.5-2 mg kg-1), but was unaffected by the thromboxane synthase inhibitor OKY 1581 (5 mg kg-1) or by pretreatment with anti-neutrophil serum. These results indicate a partial role of PAF, but demonstrate that neutrophils are not involved in the gastric vascular dysfunction induced by locally administered endothelin-1.
Asunto(s)
Permeabilidad Capilar/efectos de los fármacos , Endotelinas/toxicidad , Endotelio Vascular/efectos de los fármacos , Mucosa Gástrica/irrigación sanguínea , Factor de Activación Plaquetaria/farmacología , Animales , Azepinas/administración & dosificación , Azepinas/farmacología , Modelos Animales de Enfermedad , Endotelinas/administración & dosificación , Endotelio Vascular/lesiones , Mucosa Gástrica/efectos de los fármacos , Infusiones Intraarteriales , Marcaje Isotópico , Masculino , Metacrilatos/administración & dosificación , Metacrilatos/farmacología , Neutrófilos/citología , Neutrófilos/efectos de los fármacos , Factor de Activación Plaquetaria/antagonistas & inhibidores , Ratas , Ratas Wistar , Albúmina Sérica/metabolismo , Úlcera Gástrica/inducido químicamente , Tromboxano-A Sintasa/antagonistas & inhibidores , Triazoles/administración & dosificación , Triazoles/farmacologíaRESUMEN
Local intra-arterial infusion of high doses of the nitric oxide (NO) donor, nitroprusside (10-40 micrograms kg-1 min-1 for 15 min) induced dose-dependent haemorrhagic injury to the rat gastric mucosa and reduced systemic arterial blood pressure, whereas intragastric nitroprusside (10-50 mg ml-1), which caused similar falls in blood pressure, failed to induce such injury. The mucosal damage induced by nitroprusside was reduced by local concurrent infusion of superoxide dismutase (500-4000 i.u. kg-1). Local superoxide dismutase also abolished the mucosal injury induced by local infusion of the NO donor, S-nitroso-N-acetyl-penicillamine (40 micrograms kg-1 min-1), but not that induced by local infusion of endothelin-1 (5 pmol kg-1 min-1) indicating specific actions. Intravenous infusion of the iron chelator and peroxyl scavenger, desferrioxamine (0.25-1 mg kg-1 min-1) or the hydroxyl radical scavenger, dimethylthiourea (20 mg kg-1 min-1) also reduced the mucosal damage induced by the local administration of the NO donors, but not that induced by endothelin-1. These findings implicate the involvement of superoxide and possibly other oxygen-derived free radicals in the injurious actions of high levels of nitric oxide generated from NO donors, and may reflect a role of the cytotoxic peroxynitrite moiety.
Asunto(s)
Depuradores de Radicales Libres/farmacología , Mucosa Gástrica/efectos de los fármacos , Nitroprusiato/toxicidad , Penicilamina/análogos & derivados , Especies Reactivas de Oxígeno/efectos adversos , Vasodilatadores/toxicidad , Animales , Presión Sanguínea/efectos de los fármacos , Catalasa/administración & dosificación , Catalasa/farmacología , Catalasa/uso terapéutico , Deferoxamina/administración & dosificación , Deferoxamina/farmacología , Deferoxamina/uso terapéutico , Modelos Animales de Enfermedad , Sobredosis de Droga , Sinergismo Farmacológico , Endotelinas/administración & dosificación , Endotelinas/toxicidad , Depuradores de Radicales Libres/administración & dosificación , Depuradores de Radicales Libres/uso terapéutico , Mucosa Gástrica/patología , Infusiones Intraarteriales , Infusiones Intravenosas , Masculino , Nitratos/metabolismo , Óxido Nítrico/metabolismo , Nitroprusiato/administración & dosificación , Penicilamina/administración & dosificación , Penicilamina/toxicidad , Ratas , Ratas Wistar , S-Nitroso-N-Acetilpenicilamina , Úlcera Gástrica/inducido químicamente , Úlcera Gástrica/tratamiento farmacológico , Superóxido Dismutasa/administración & dosificación , Superóxido Dismutasa/farmacología , Superóxido Dismutasa/uso terapéutico , Tiourea/administración & dosificación , Tiourea/análogos & derivados , Tiourea/farmacología , Tiourea/uso terapéutico , Vasodilatadores/administración & dosificaciónRESUMEN
The high K(+)-evoked dopamine release from rat striatal slices remained impaired by 50% up to 2 h after pulse exposure of the tissues to endothelin-3, under conditions of hypoglycemia/hypoxia. This striatal dysfunction was significantly improved by D-2-amino-5-phosphonopentanoic acid, a NMDA receptor antagonist, at a much lower concentration than that providing protection against NMDA-evoked dysfunction. In light of these findings, the important role of glutamatergic mechanisms, especially NMDA receptors, in mediating endothelin neurotoxicity warrants further attention.
Asunto(s)
Endotelinas/toxicidad , Neostriado/citología , Neuronas/efectos de los fármacos , Receptores de N-Metil-D-Aspartato/efectos de los fármacos , 2-Amino-5-fosfonovalerato/farmacología , Ácido 3-piridinacarboxílico, 1,4-dihidro-2,6-dimetil-5-nitro-4-(2-(trifluorometil)fenil)-, Éster Metílico/toxicidad , Animales , Dopamina/metabolismo , Técnicas In Vitro , Masculino , N-Metilaspartato/toxicidad , Neostriado/efectos de los fármacos , Neostriado/metabolismo , Neuronas/metabolismo , Nifedipino/farmacología , Potasio/farmacología , Cloruro de Potasio/farmacología , Ratas , Ratas WistarRESUMEN
The effects of diltiazem and phosphoramidon on sudden death induced by endothelin (ET)-1 and by big ET-1 were compared in rodents. Diltiazem (2 mg/kg, i.v.) remarkably diminished the lethal toxicity of ET-1 with a reduction in the extent of the rise in plasma immunoreactive ET-1-like activity (IR-ET-1), tissue IR-ET-1 accumulation in the heart and the rise in plasma potassium concentration. In big ET-1-induced lethality, diltiazem only slightly prolonged the latency and did not reduce the mortality. Although diltiazem moderately inhibited the rise in plasma IR-ET-1 and potassium concentration in these mice, it did not affect the accumulation of IR-ET-1 in the heart, lung or kidney. Phosphoramidon (2 mg/kg, i.v.) decreased the lethality of big ET-1 with the decrement in elevation of IR-ET-1 in the heart, lung and plasma as well as with the decrease in plasma potassium concentration, but it failed to improve any parameters in ET-1-induced lethality. In anesthetized rats, ET-1 (5 nmol/kg, i.v.) elevated ST-segment of electromyocardiograms, and diltiazem (2 mg/kg, i.v.) significantly reversed this change. Big ET-1 (25 nmol/kg, i.v.) also induced the ST-segment elevation, which was significantly inhibited by phosphoramidon but not by diltiazem. These findings suggest that accumulation of ET-1 in the heart, which may lead to lethal cardiac ischemia, is an important factor in the lethality of ET-1, while additional factors (such as hemoconcentration and bronchoconstriction) may be involved in big ET-1-induced lethality.
Asunto(s)
Muerte Súbita Cardíaca , Endotelinas/toxicidad , Precursores de Proteínas/toxicidad , Anestesia , Animales , Diltiazem/farmacología , Electrocardiografía , Endotelina-1 , Endotelinas/antagonistas & inhibidores , Endotelinas/metabolismo , Glicopéptidos/farmacología , Riñón/metabolismo , Pulmón/metabolismo , Masculino , Ratones , Ratones Endogámicos ICR , Isquemia Miocárdica/inducido químicamente , Miocardio/metabolismo , Potasio/sangre , Inhibidores de Proteasas/farmacología , Precursores de Proteínas/antagonistas & inhibidores , Precursores de Proteínas/metabolismoRESUMEN
Endothelins (ET) are the most important vasoconstrictors known, and administration results in contraction of vascular strips in man and experimental animals in vitro. We examined the effects of ET-1 on thrombus formation in rabbits. We used vasoconstrictor and thrombus forming agents and we selected an animal model, the vena jugularis thrombus model. In addition, intravascular endothelium was examined ultrastructurally. The ET-1 level is known to be high in patients with hypertension; if these patients also have atherosclerosis, then intravascular thrombus formation may increase. In the vena jugularis thrombus model, thromboplastin and ET-1 act synergistically to increase intravascular thrombus formation. On injection of ET-1 dose dependent vasoconstriction was shown in the vessel wall. Although similar maximal contraction is achieved, a decrease in vessel diameter is associated with increased potency of ET-1 and thromboplastin. The results suggest that ET-1 may regulate vascular tone through constriction of vessels.
Asunto(s)
Endotelinas/toxicidad , Venas Yugulares/efectos de los fármacos , Tromboembolia/inducido químicamente , Tromboplastina/toxicidad , Animales , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Venas Yugulares/patología , Masculino , ConejosRESUMEN
Adult rat ventricular cardiocytes, when cocultured with epicardial mesothelial cells (EMC), demonstrate remarkable plasticity of phenotype accompanied by a significant increase in cardiocyte contractile protein content, suggesting that a factor with growth-promoting properties may take part in EMC-adult rat ventricular cardiocyte interactions. Endothelin (ET) has been shown to induce cell hypertrophy, including enhancement of expression of muscle-specific genes. We investigated the ability of EMC to synthesize and release ET. By light microscopy, specific immunostaining, with either ET-1 or Big ET-1 antibodies, was visualized in EMC as a fine punctate distributed throughout the cytoplasm. Reverse phase-high performance liquid chromatography (HPLC) of epicardial mesothelial cells conditioned medium showed several peaks of immunoreactive ET. The major peak eluted with the same retention time as that of ET-1. By Northern blot analysis, a specific 2.3-kilobase (kb) mRNA species was detected by hybridization to a cDNA insert encoding for rat prepro-ET-1. ET accumulated in the culture medium in a time-dependent manner, whereas cell content remained comparatively low. Angiotensin II (AII) dose-dependently stimulated release of immunoreactive ET into the culture medium.
Asunto(s)
Endotelinas/biosíntesis , Pericardio/citología , Angiotensina II/toxicidad , Animales , Anticuerpos Monoclonales , Northern Blotting , División Celular/efectos de los fármacos , Células Cultivadas , Cromatografía Líquida de Alta Presión , Reacciones Cruzadas , Relación Dosis-Respuesta a Droga , Endotelinas/genética , Endotelinas/toxicidad , Células Epiteliales , Epitelio/efectos de los fármacos , Epitelio/metabolismo , Epitelio/ultraestructura , Regulación de la Expresión Génica/genética , Ventrículos Cardíacos/citología , Masculino , Microscopía Electrónica , Hibridación de Ácido Nucleico , Pericardio/efectos de los fármacos , Pericardio/metabolismo , Pericardio/ultraestructura , ARN Mensajero/metabolismo , Radioinmunoensayo , Ratas , Ratas Sprague-DawleyRESUMEN
We have recently reported that the submucosal injection of endothelin-1 induces gastric ulcers in rats. In the present study, we have examined the time sequence of the macroscopic, histologic and ultramicroscopic features of the formation and development of the gastric ulcer induced by endothelin-1 (100 pmol submucosally). In rats, we examined the effect of endothelin-1 on the gastric mucosa macroscopically, on the gastric mucosal cells and vessels by light microscopy and on the ultra-structure of the gastric mucosal surface and of the gastric glands by electron microscopy. Gastric mucosal changes were evaluated 1, 4, 30 minutes, 1, 4, 8, 16, 20, 24 hours and 2, 4, 7, 14, 21 days after teh submucosal injection of endothelin-1. Application of endothelin-1 was immediately followed by arterial vasoconstriction and venous dilatation, 5 minutes later by interstitial haemorrhage and 30 minutes later by demise of epithelial cells. Electron microscopy showed almost complete exfoliation of the inter-pit cells 30 minutes after the injection. By 1 hour, superficial redness, apoptosis of superficial cells and loss of the intra-pit cells was detected. By 8 hours, there was mucosal haemorrhage and complete loss of intra-pit cells from the basal part of the gastric glands. Forty-eight hours later, there was a deep gastric ulcer with penetration of the muscularis mucosae. By 4 days, the ulcers had entered the chronic phase and by 1 week abnormal glands were covering the area of damage with no mucous production. By 3 weeks the damaged area was still structurally abnormal. The results of this study suggest that injury to the microvasculature may initiate the degenerative and structural changes of the gastric mucosa that lead to the production of this novel type of experimental gastric ulcer in rats.
Asunto(s)
Modelos Animales de Enfermedad , Endotelinas/toxicidad , Mucosa Gástrica/ultraestructura , Úlcera Gástrica/etiología , Úlcera Gástrica/patología , Animales , Cinética , Masculino , Microscopía Electrónica de Rastreo , Ratas , Ratas Wistar , Estómago/irrigación sanguínea , Vasoconstricción , VasodilataciónRESUMEN
The 21 amino acid sarafotoxins (SRTX) c and d/e as well as endothelin-3 (ET-3) are known to be less toxic and weaker pharmacologically than the other isopeptides SRTX-a, SRTX-b and ET-1. Since SRTX-c, SRTX-d/e and ET-3 possess a Thr instead of a Ser at position 2, we investigated the possibility that this mutation could be responsible for the observed biological differences. Here we show that the synthetic [Thr2]SRTX-b has indeed a lower vasoconstriction efficacy (approximately 35%) in the rabbit aorta, but it is nearly as potent as SRTX-b in toxicity tests and in influencing contraction of the rat uterus. Using monoclonal antibodies directed against the structurally related endothelin-1, we also show that the antigenicity of the analogue is comparable to that of SRTX-b, suggesting that the overall structure of the two peptides is similar, despite the substitution at position 2. We suggest that the Thr2 substitution contributes to the lower activity of the 'weak' peptides in some systems; however, additional substitutions found in the 'weak' peptides of the ET/SRTX family most probably contribute to their low pharmacological activity.
Asunto(s)
Músculo Liso Vascular/efectos de los fármacos , Contracción Uterina/efectos de los fármacos , Vasoconstrictores/toxicidad , Venenos de Víboras/toxicidad , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales , Especificidad de Anticuerpos , Aorta/efectos de los fármacos , Unión Competitiva , Cromatografía Líquida de Alta Presión , Electrocardiografía/efectos de los fármacos , Endotelinas/química , Endotelinas/inmunología , Endotelinas/toxicidad , Femenino , Técnicas para Inmunoenzimas , Dosificación Letal Mediana , Ratones , Datos de Secuencia Molecular , Contracción Muscular/efectos de los fármacos , Conejos , Ratas , Relación Estructura-Actividad , Vasoconstricción/efectos de los fármacos , Vasoconstrictores/química , Venenos de Víboras/química , Venenos de Víboras/clasificaciónRESUMEN
The influence of endothelin-1 on ventricular fibrillation threshold was studied in acute myocardial ischemic rats. Endothelin-1 (1.5-3.0 micrograms.kg-1 i.v.) given 5 min before ischemia reduced the ventricular fibrillation threshold in a dose- and time-dependent manner. Its effect lasted at least 60 min. A marked increase of spontaneous ventricular tachycardia and myocardial infarct size was seen and the arterial blood pressure was at a higher level (18.5-20.1/14.4-15.8 kPa) after 3.0 micrograms.kg-1. Diltiazem prevented partially from reduction of ventricular fibrillation threshold, eliminated completely the vasopressor response and limited the extension of myocardial necrosis induced by endothelin-1.