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Thursday 01 February 2001

Adrenergic airway vascular smooth muscle responsiveness in healthy and asthmatic subjects.

By: Brieva J, Wanner A.

J Appl Physiol 2001 Feb;90(2):665-9

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 (alpha(1)-agonist; 0.6-2.3 mg) and albuterol (beta(2)-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 microl. 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 microl. min(-1). ml(-1) in asthmatic and -7.1 +/- 2.1 microl. min(-1). ml(-1) in healthy subjects (P < 0.05). After albuterol, the mean maximal change in Qaw was 3.0 +/- 0.8 microl. min(-1). ml(-1) in asthmatic and 14.0 +/- 1.1 microl. min(-1). ml(-1) in healthy subjects (P < 0.05). These results demonstrate that the contractile response of AVSM to alpha(1)-adrenoceptor activation is enhanced and the dilator response of AVSM to beta(2)-adrenoceptor activation is blunted in asthmatic subjects.

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