1. Using a guinea-pig model of allergic asthma, we investigated the role of L-arginine limitation in the allergen-induced deficiency of nitric oxide (NO) and airway hyperreactivity (AHR) after the early asthmatic reaction, by examining the effects of various concentrations of the NO synthase (NOS) substrate on the responsiveness to methacholine of isolated perfused tracheae from unchallenged (c...

BACKGROUND Conflicting views exist over whether responsiveness of the airways to hypertonic saline relates to non-specific bronchial hyperresponsiveness measured by histamine or methacholine challenge. The bronchoconstrictor responses to exercise and hypertonic saline are reported to be closely related, but the relationship between the symptoms of exercise induced asthma and airway responsivene...

Inhalation treatment may be less effective in the presence of bronchoconstriction because of the reduced penetration of drugs into the airways. The effect of bronchoconstriction on the lung deposition and plasma pharmacokinetics of inhaled sodium cromoglycate was examined. Ten subjects attended the laboratory on three occasions. On the first occasion a bronchial provocation test was performed t...

RATIONALE In a modified methacholine provocation test that was used to study changes in airway responsiveness to occupational irritants or sensitizers in healthy subjects, two protocols were used: a long protocol (doubling methacholine concentrations between dose steps) or a short protocol (fourfold increases in concentration). This modified methacholine provocation allows measurements of the p...

Cholinergic agents (e.g., methacholine) induce cutaneous vasodilation and sweating. Reports indicate that either nitric oxide (NO), cyclooxygenase (COX), or both can contribute to cholinergic cutaneous vasodilation. Also, NO is reportedly involved in cholinergic sweating; however, whether COX contributes to cholinergic sweating is unclear. Forearm sweat rate (ventilated capsule) and cutaneous v...

In a guinea pig model of allergic asthma, we have recently established that a deficiency of nitric oxide (NO) contributes to the increased ex vivo responsiveness of isolated perfused tracheae to methacholine after the early asthmatic reaction at 6 h after inhalational challenge of the animals with ovalbumin aerosol. Because this deficiency could be caused by a reaction of NO with enhanced level...

BACKGROUND The distribution of airway responsiveness in a general population of non-smokers without respiratory symptoms has not been established, limiting its use in clinical and epidemiological practice. We derived reference equations depending on individual characteristics (i.e., sex, age, baseline lung function) for relevant percentiles of the methacholine two-point dose-response slope. M...