Inhalation of adenosine 5'-monophosphate increases methacholine airway responsiveness.
Airway hyperresponsiveness is a characteristic feature in asthmatic subjects, but the mechanism of the hyperresponsiveness is not known. The purpose of this study was to investigate whether methacholine airway responsiveness was increased 24 h after inhalation of adenosine 5'-monophosphate (AMP). Ten atopic asthmatic subjects and six atopic normal subjects were studied on 4 study days. On the 1st day, a methacholine inhalation test was performed, followed within 48 h by an AMP inhalation test. Seven days later the second AMP test was performed, and 24 h later the methacholine inhalation test was repeated. Response was measured using partial flow-volume curves, and the concentration required to cause a 40% fall in the partial flow-volume curve (PC40) was calculated. The geometric mean methacholine PC40 fell from 1.36 mg/ml on day 1 (before AMP inhalation) to 0.71 mg/ml on day 4 (24 h after AMP inhalation, P less than 0.01). There was no change in the mean PC40 for adenosine on the 2 study days (5.82 and 7.06 mg/ml, P greater than 0.1). These findings suggest that adenosine release may contribute to the increase in airway responsiveness after allergen challenge.
Rosati
G
G
Department of Medicine, St. Joseph's Hospital, Hamilton, Ontario, Canada.
Hargreave
F E
FE
Ramsdale
E H
EH
D000249:Adenosine Monophosphate / Q000494:pharmacology*; D000280:Administration, Inhalation; D000328:Adult; D000403:Airway Resistance / Q000187:drug effects*; D001249:Asthma / Q000188:drug therapy*; D001944:Breath Tests; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology*; D008875:Middle Aged; D013997:Time Factors
D008688:Methacholine Compounds; D000249:Adenosine Monophosphate