Interactive Acute Smooth Muscle Effects of Salmeterol and Fluticasone in the Airway

The addition of an inhaled long-acting beta-adrenergic agonist to an inhaled glucocorticosteroid improves disease control in persistent asthma. This observation has supported the use of long-acting beta-adrenergic agonist/glucocorticosteroid combination preparations for the management of asthma. Currently, salmeterol/fluticasone and formoterol/budesonide are available for clinical use. The long-term beneficial clinical effects of the two drug classes seem to be synergistic, and several mechanisms of glucocorticoid-beta-adrenergic agonist interactions involving gene transcription have been invoked to explain this phenomenon.This study, wish to address the question whether glucocorticoids can acutely potentiate the bronchodilator response to a long-acting beta-adrenergic agonist.We expect that in patients with asthma, the short-term bronchodilator effect of salmeterol is enhanced by the addition of fluticasone, which by itself has no short-term bronchodilator effect. To test this premise, we will assess the respective short-term effects of salmeterol (50 µg), fluticasone (250 µg), salmeterol/fluticasone (50/250 µg), and placebo/placebo on spirometric parameters. Airway Blood flow will also be measured to ensure that vasoconstriction does not occur.