Beta-adrenoceptor agonists are potent and selective relaxants of airway smooth muscle. They produce symptomatic bronchodilatory effects and are the most widely used therapy in asthma. In patients with asthma, they usually effect a reduction of airway resistance, but there have been several reports of episodes of increased airway obstruction, arterial hypoxaemia and even death associated with su...

Airflow limitation in COPD is a result partially of bronchospasm, but it is also caused by a reduction in airway caliber, the number of small airways, airway collapse because of loss of connective tissue support, excess mucus in the airways, and edema of the airway wall. Structural changes also occur because of long-term destruction of interstitial connective tissue, including elastin. Therefor...

In order to study the potential benefit of ascorbic acid in asthma we investigated its role in exercise-induced bronchospasm (EIB). Twelve asthmatic subjects were recruited on the basis of findings compatible with EIB. On two subsequent days the subjects ingested 500 mg. of ascorbic acid or a placebo. The study was performed in a double-blind randomized fashion. Partial and maximal expiratory f...