RESUMEN
In vibratome-cut slices from rat striatum and in the presence of 10 mM LiCl, the cholinergic agonist carbachol stimulated the accumulation of total [3H]inositol phosphates (EC50 11+/-1 microM and maximum effect 546+/-36% of basal). The response to 100 microM carbachol (497+/-24% of basal) was inhibited by muscarinic antagonists (1 microM), the rank order of efficacy being 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; 100% inhibition) approximately pirenzepine (98+/-3%) > p-fluoro analog of hexahydro-sila-difenidol (pFHHSiD; 90+/-3%) >> methoctramine (32+/-7%) approximately tropicamide (30+/-10%). Antagonist inhibition curves best fit to a single-site model for 4-DAMP (pKi 8.9+/-0.2) whereas, for both pirenzepine and pFHHSiD, the best fit was to the two-site model. The pKi values for the high-affinity (8.3+/-0.2) and low-affinity (6.9+/-0.2) components for pirenzepine-mediated inhibition corresponded to those reported for M1 and M3 receptors, respectively. The pKi values for the high-affinity (8.2+/-0.3) and low-affinity (7.0+/-0.2) components for pFHHSiD inhibition were in good agreement with those reported for M3 and M1 receptors, respectively. Altogether these results indicate that carbachol-induced [3H]inositol phosphate formation in rat striatal slices is mediated by both M1 and M3 muscarinic receptors.
Asunto(s)
Carbacol/farmacología , Cuerpo Estriado/efectos de los fármacos , Fosfatos de Inositol/biosíntesis , Antagonistas Muscarínicos/farmacología , Animales , Cuerpo Estriado/metabolismo , Evaluación Preclínica de Medicamentos , Técnicas In Vitro , Piperidinas/farmacología , Pirenzepina/farmacología , Ratas , Ratas WistarRESUMEN
In cross-chopped slices from rat thalamus and in the presence of 10 mM LiCl, noradrenaline stimulated the accumulation of [3H]inositol phosphates with [3H]inositol monophosphates ([3H]IP1) being the major product detected (86 +/- 2% of total [3H]inositol phosphates). Noradrenaline-induced [3H]IP1 accumulation was concentration-dependent and yielded and EC50 of 4.6 +/- 0.2 microM, maximum effect of 272 +/- 3% of basal formation and Hill coefficient (nH) of 1.6 +/- 0.1. The effect of 100 microM noradrenaline was inhibited by the alpha 1-adrenoceptor antagonists prazosin, (+)-niguldipine, 5-methylurapidil and WB-4101 (2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1,4-benzodioxane). The inhibition curve for prazosin best fit to a single-site model whereas curves for (+)-niguldipine, 5-methylurapidil and WB-4101 best fit to a two-site model. The putative alpha 1D-adrenoceptor-selective antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8- azaspiro[4.5]decane-7,9-dione) showed low potency and efficacy to inhibit the response to noradrenaline. Pre-treatment of the slices with chloroethylclonidine (100 microM; 30 min) decreased by 64 +/- 4% the maximum response. Noradrenaline-induced [3H]IP1 accumulation was significantly reduced by Ca2+ removal (by 64 +/- 2%) and by the Ca(2+)-channel blockers Ni2+, Co2+ and nimodipine (inhibition of 56 +/- 6%, 54 +/- 5% and 41 +/- 5%, respectively). Taken together these results indicate that noradrenaline-induced inositol phosphate formation in thalamus slices is mainly mediated by the activation of both alpha 1B and alpha 1A subtypes of alpha 1-adrenoceptors.
Asunto(s)
Agonistas alfa-Adrenérgicos/farmacología , Fosfatos de Inositol/biosíntesis , Norepinefrina/farmacología , Receptores Adrenérgicos alfa 1/metabolismo , Tálamo/metabolismo , Animales , Calcio/farmacología , Clonidina/análogos & derivados , Clonidina/farmacología , Dioxanos/farmacología , Técnicas In Vitro , Masculino , Ratas , Ratas Wistar , Receptores Adrenérgicos alfa 1/efectos de los fármacos , Tálamo/efectos de los fármacosAsunto(s)
Animales Salvajes/inmunología , Anticuerpos Antivirales/análisis , Arenaviridae/inmunología , Arenavirus del Nuevo Mundo/inmunología , Fiebre Hemorrágica Americana/inmunología , Roedores/inmunología , Adolescente , Adulto , Animales , Animales Salvajes/microbiología , Arenavirus del Nuevo Mundo/patogenicidad , Argentina , Niño , Preescolar , Reservorios de Enfermedades , Femenino , Cobayas , Fiebre Hemorrágica Americana/microbiología , Humanos , Masculino , Ratones , Persona de Mediana Edad , Roedores/microbiologíaAsunto(s)
Arenaviridae/patogenicidad , Arenavirus del Nuevo Mundo/patogenicidad , Cebidae , Cebus , Fiebre Hemorrágica Americana/microbiología , Animales , Antígenos Virales/análisis , Arenavirus del Nuevo Mundo/inmunología , Arenavirus del Nuevo Mundo/aislamiento & purificación , Peso Corporal , Masculino , Recuento de PlaquetasRESUMEN
Ultrastructural and immunohistochemical studies on tissues from five patients with Argentine hemorrhagic fever revealed previously undetected lesions caused by the viral infection. Two types of particle were seen in the cells of all organs examined. The particles had some characteristics similar to those described for arenaviruses. However, the virus-like particles were intracellular, had a single membrane, and apparently originated by a process of budding into the endoplasmic reticulum cisternae. Intranuclear bodies and three types of cytopolasmic change were observed in conjunction with the virus-like particles; Antigenic determinants of Junin virus were demonstrated in cells of all organs examined. Immunohistochemical experiments also indicated alterations in the cellular mechanisms of protein synthesis. Until now the pathogenesis of human diseases produced by arenaviruses has not been established. The results of this study suggest that in Argentine hemorrhagic fever the virus is responsible for a direct pathogenic action.