The purpose of the present study was to determine the responsiveness of airway vascular smooth muscle (AVSM) as assessed by airway mucosal blood flow (Qaw) to inhaled methoxamine (α1-agonist; 0.6-2.3 mg) and albuterol (β2-agonist; 0.2-1.2 mg) in healthy [n = 11; forced expiratory volume in 1 s, 92 ± 4 (SE) % of predicted] and asthmatic (n = 11, mean forced expiratory volume in 1 s, 81 ± 5%) adults. Mean baseline values for Qaw were 43.8 ± 0.7 and 54.3 ± 0.8 μl·min-1·ml-1 of anatomic dead space in healthy and asthmatic subjects, respectively (P < 0.05). After methoxamine inhalation, the maximal mean change in Qaw was -13.5 ± 1.0 μl·min-1·ml-1 in asthmatic and -7.1 ± 2.1 μl·min-1·ml-1 in healthy subjects (P < 0.05). After albuterol, the mean maximal change in Qaw was 3.0 ± 0.8 μl·min-1·ml-1 in asthmatic and 14.0 ± 1.1 μl·min-1·ml-1 in healthy subjects (P < 0.05). These results demonstrate that the contractile response of AVSM to α1-adrenoceptor activation is enhanced and the dilator response of AVSM to β2-adrenoceptor activation is blunted in asthmatic subjects.
- Adrenergic agonists
- Bronchial blood flow
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation