Arachidonic acid- and methacholine-induced contractions of rabbit pulmonary arteries are mediated by thromboxane (TX) A2. Although removal of the endothelium abolishes the contractions, endothelial cells isolated from pulmonary arteries do not synthesize TXA2. Further studies described here showed that the expression of TX synthase was evident in platelets and intact pulmonary artery but not in...

We investigated the hypothesis that prior airway muscarinic receptor stimulation (with aerosolized methacholine) would modify the bronchoconstrictor response to histamine, which is, in part, vagally mediated. On four different experiment days, the following combinations of methacholine and histamine inhalation challenges were performed in 15 subjects (nine normal and six asthmatic) in a random ...

We examined the hypothesis that a forced expiratory volume in one second (FEV1) manoeuvre (and the preceding deep inhalation) before inhalation of methacholine might influence FEV1 measured after methacholine, if the time between measurements was short. Six to nine healthy subjects inhaled a single dose of methacholine, known to cause about 20% decrease in FEV1, on different days in different t...

Bronchial hyperresponsiveness (BHR) is a key feature of asthma and may be measured by direct methacholine challenge or indirect adenosine monophosphate (AMP) challenge. We performed a retrospective analysis of our database (n = 487) of patients with asthma with the aim first, to compare methacholine and AMP challenge as screening tools, and second, to identify any relationships between BHR and ...

BACKGROUND The airway muscles from allergen-sensitized animals in vitro show a heightened response to histamine, but not to carbachol. This study investigated whether the airway responsiveness to histamine in vivo is comparable to that of methacholine in human subjects with varying degrees of atopy. METHODS One-hundred-and-sixty-eight consecutive adult asthma patients or volunteers underwent ...

In normal subjects in vivo the dose-response curve to inhaled nonsensitizing stimuli reaches a plateau at mild degrees of airway narrowing. We investigated whether the limitation of the response is due to non-optimal smooth muscle activation, by administering high doses of histamine and methacholine together. In fifteen normal subjects a complete dose-response curve to methacholine was recorded...

3-hydroxy-3-methylglutaryl-CoA reductase inhibitors (statins), are effective serum cholesterol-lowering agents which also have anti-inflammatory properties. The objective of this study was to evaluate the effect of atorvastatin on bronchial hyperresponsiveness. Adult patients (age 14 to 65 years) with bronchial hyperresponsiveness (BHR) diagnosis based on the spirometry with methacholine challe...

Methacholine chloride solutions, routinely used for testing bronchial hyperreactivity, have been shown to degrade over time. The data published addressing the optimal conditions for methacholine chloride storage are conflicting and incomplete. This study investigated the effects of a variety of conditions on the stability of methacholine chloride. Methacholine chloride, dissolved in phosphate b...