Adrenergic airway vascular smooth muscle responsiveness in healthy and asthmatic subjects.
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.
Brieva
J
J
Division of Pulmonary and Critical Care Medicine, University of Miami School of Medicine at Mount Sinai Medical Center, Miami Beach, Florida 33140, USA.
Wanner
A
A
D000280:Administration, Inhalation; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage* / Q000494:pharmacology; D001249:Asthma / Q000503:physiopathology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000098:blood supply / Q000503:physiopathology; D008297:Male; D008729:Methoxamine / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000294:innervation* / Q000503:physiopathology; D011652:Pulmonary Circulation; D012126:Respiratory Dead Space; D020545:Respiratory Mucosa / Q000098:blood supply; D014661:Vasoconstriction; D014664:Vasodilation
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D008729:Methoxamine; D000420:Albuterol