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.

Fourteen lifetime nonsmokers with a physician diagnosis of asthma will be recruited for the study. All subjects will be allowed to use short-acting beta-adrenergic agonists as rescue medication.

Inclusion criteria:

1. Males and females, 18 to 65 years of age.
2. FEV1 60-85% of predicted on the screening day.

Exclusion criteria:

1. Women of childbearing potential who do not use accepted birth control measures; pregnant and breast feeding women.
2. Cardiovascular disease and/or use of cardiovascular medications

2. Subjects with known beta-adrenergic agonist or glucocorticosteroid intolerance 4. Acute respiratory infection within four weeks prior to the study 5. Use, within two weeks prior to the study, of any anti-asthma medication not mentioned above

Inclusion Criteria:

1. Males and females, 18 to 65 years of age.
2. FEV1 60-85% of predicted on the screening day. -

Exclusion Criteria:

1. Women of childbearing potential who do not use accepted birth control measures; pregnant and breast feeding women. 2. Cardiovascular disease and/or use of cardiovascular medications 3. Subjects with known beta-adrenergic agonist or glucocorticosteroid intolerance 4. Acute respiratory infection within four weeks prior to the study 5. Use, within two weeks prior to the study, of any anti-asthma medication not mentioned above

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Fourteen lifetime nonsmokers with a physician diagnosis of asthma were recruited for the study. All but one of the subjects were using an ICS/LABA combination preparation regularly, and all used a short-acting b2-adrenergic agonist as rescue medication. All subjects had to have a prebronchodilator FEV1 of 60% to 85% predicted .