This study will investigate potential differences in how two puffs of salbutamol protects airway smooth muscle from contracting in people with asthma and chronic obstructive pulmonary disease (COPD).

Brief Title

Bronchoprotection of Salbutamol in Asthma and Chronic Obstructive Pulmonary Disease

Official Title

Bronchoprotection of Salbutamol in Asthma and COPD

Brief Summary

This study will investigate potential differences in how two puffs of salbutamol protects<br /> airway smooth muscle from contracting in people with asthma and chronic obstructive pulmonary<br /> disease (COPD).

Detailed Description

In asthma, the administration (inhalation) of a selective β2 receptor agonist (e.g.
salbutamol), prior to methacholine challenge has been shown to shift the dose response curve
to the right and "bronchoprotect" the airway against airway smooth muscle contraction. The
extent of β2 receptor agonist bronchoprotection in COPD is unknown.

Airway hyperresponsiveness (AHR) to direct acting agents such as histamine and methacholine
is a feature of both asthma and COPD. In asthma, the abnormality leading to AHR is believed
to be due to changes in airway smooth muscle (e.g. hypertrophy, hyperplasia, contractile
apparatus) whereas in COPD the AHR is likely due to structural or geometric changes.

The investigators hypothesize that the bronchoprotection afforded by salbutamol against
methacholine challenge will be greater in asthma than in COPD due to differences in
underlying airway abnormalities.