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Primates secrete large amounts of the precursor steroid dehydroepiandrosterone (DHEA); in humans, its levels are low during childhood and start declining after the fourth decade. It has been postulated that the progressive decline in DHEA levels may be related with the severity of asthma associated with age. To determine whether DHEA may regulate the airway smooth muscle (ASM) activity, isolated tracheal rings with and without epithelium from male guinea pigs were isometrically recorded to characterize the response of ASM to DHEA at different concentrations on KCl- and carbachol (CCh)-induced contraction as well as on ovalbumin (OVA)-induced contraction in sensitized guinea pigs. Additionally, we used barometric plethysmography in sensitized guinea pigs in order to compare changes of the lung resistance increased by the antigen challenge to OVA in the absence and presence of different doses of DHEA. DHEA concentration-dependently abolished the contraction to KCl, CCh and OVA, and no differences were found in preparations with and without epithelium. DHEA-induced relaxation was not modified by the suppression of protein synthesis or transcription, pharmacological inhibition of nitric oxide (NO) synthase, nor by antagonist of ß2-adrenergic receptors or an inhibitor of the 3ß-HSD enzyme. Likewise, Ca(2+)-induced contraction in Ca(2+)-free depolarized tissues was antagonized by DHEA, and the contraction to the L-type voltage-dependent calcium channel activator (Bay K 8644) was inhibited by DHEA. Furthermore, DHEA prevented OVA-induced increases in lung resistance. These results indicate that DHEA-induced relaxation in ASM is a nongenomic (membrane) action and is not produced after its bioconversion. The data suggest that DHEA-induced relaxation is an epithelium- and NO-independent mechanism that involves a blockade of voltage-dependent calcium channels and possible non-selective cation channels.

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A standardized aqueous extract (AE) and a purified fraction (BuF) of Cecropia glaziovi Sneth leaves were tested in unrestrained guinea pigs challenged with histamine. Changes of the respiratory pressure and rate were recorded in a whole body plethysmograph before and after treatment. The concentration of histamine necessary to produce bronchospasm was increased by five-fold following administration of AE (1.0 g/kg p.o.), and by two-fold after treatment with the semi-purified procyanidin/flavonoids enriched BuF (0.1 g/kg p.o.). Both effects were blocked by previous treatment with propranolol (10.0 mg/kg i.p.). In vitro incubation of BuF (0.1-1.0 mg/ml) decreased by 13-55% the maximal response of guinea pig tracheal muscle to histamine, without significant change of EC50. The results confirmed old reports on the useful pulmonary effects of Cecropia extracts. The bronchodilation observed in vivo seems to be related to beta-adrenergic activity observed in vitro only with high concentrations of the purified extract.

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BACKGROUND: Exercise-induced asthma is a syndrome characterized by dyspnea, thoracic pain, cough, sibilant rales and diminished physical performance. It appears into the first 30 minutes after the beginning of physical activity. OBJECTIVE: To evaluate calisthenic effect on maximal expiratory flow rate in asthmatic patients. MATERIAL AND METHODS: A prospective, observational and descriptive study was done through a soccer game. Male and female asthmatic patients from 6 to 16 years old with intermittent and mild asthma were included. Maximal expiratory flow rate was measured before the beginning of soccer game, and then, at the end of the first and second sets. Statistical analysis was made through the media values comparison and t Student test. RESULTS: 60 patients were included. They were 11.3 +/- 2.4 mean aged. 45% had diagnosis of mild asthma, 36.6% mild asthma and allergic rhinitis and 6.6% persistent asthma. Average of basal maximal expiratory flow rate was 275 +/- 90 L/s, and no significant changes were observed in 52 patients: mean maximal expiratory flow rate at the end of first and second sets was 275 +/- 86 L/s and 273 +/- 96 L/s, respectively. Maximal expiratory flow rate diminished at 77 +/- 3.8% and 83 +/- 9.5% in the other eight patients at the end of the first and second sets, respectively. CONCLUSIONS: Calisthenic made before physical activity prevents maximal expiratory flow rate diminishment.

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El descubrimiento de Cromoglicato Disódico representa un importante progreso en el tratamiento del asma. Sin embargo, debido a su pobre solubilidad e incapacidad para ser absorbido del tracto gastrointestinal, la forma galénica de este medicamento es una de sus mayores desventajas relativas en la práctica clínica. Esto ha estimulado los estudios para encontrar agentes terapéuticos que sean activos y bien tolerados por vía oral. Un agente es el Ketotifeno (HC-20-511), el cual está químicamente relacionado al grupo de sustancias del tipo cicloheptathiopheno. Este producto ha mostrado varias propiedades farmacológicas en enfermedades alérgicas. Ha demostrado muy bajo nivel de toxicidad y una rápida y completa absorción a través del tubo digestivo. Nosotros reportamos la eficacia clínica y la tolerancia del Ketotifeno en un grupo de pacientes con asma bronquial de leve a moderada. El análisis estadístico de la información muestra que el uso del Ketotifeno ayuda a controlar los síntomas del asma y es una droga prometedora en el tratamiento profiláctico del asma

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De los padecimientos que puede complicar el embarazo, el asma ocupa un lugar importante, ya que afecta hasta en 4 por ciento. Cuendo no se controla se compromete la oxigenación adecuada de la madre y del hijo. Según la intensidad del asma las manifestaciones clínicas pueden ser mínimas no aparentes o aparatosas que ameriten hospitalización, por esta razón además del parámetro clínico, es necesario que la paciente determine diariamente su flujo espiratorio máximo mediante un flujómetro portátil. Para el manejo farmacológico, se deben considerar los cambios fisiológicos que hay en la gestación, como la disminución de albúmina y ciertas proteínas que se unen al medicamento dando como resultado mayor fármaco libre activo, esto es particularmente importante como es el caso de teofilinas que además de lo anterior el aclaramiento de ésta se encuentra disminuido. Para fines prácticos se deben utilizar broncodilatadores beta dos solo por razón necesaria, prefiriendo la vía inhalada y en caso necesario el empleo de ciclo corto de esteroides. El manejo debe tener como objetivo el control de síntomas, evitar recaídas, función pulmonar lo más cercana a lo normal para lograr un estado satisfactorio del binomio madre-hijo

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