The Journal of allergy and clinical immunology
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J. Allergy Clin. Immunol. · Sep 1990
Randomized Controlled Trial Clinical TrialRepeated exposure of asthmatic airways to inhaled adenosine 5'-monophosphate attenuates bronchoconstriction provoked by exercise.
Inhaled adenosine 5'-monophosphate (AMP) induces bronchoconstriction in subjects with asthma, probably caused by histamine release from airway mast cells, and repeated AMP bronchial challenge leads to attenuation of the bronchoconstrictor response. Since exercise-induced bronchoconstriction may be mediated by hypertonic mast cell degranulation, we postulated that repeated AMP bronchial challenge should reduce the response to subsequent exercise challenge. Eight atopic subjects with asthma took part in an unblinded, randomized trial. ⋯ On the AMP study day, the geometric mean PC20 was 15.3 (7.9 to 29.5) mg/ml for the first test, and 28.2 (10.7 to 77.4) mg/ml for the third test (not significant). On the control study day, the mean maximum percentage fall in FEV1 after exercise was 28.0% +/- 2.7%, whereas on the AMP study day, it was reduced to 13.0% +/- 4.3% (p less than 0.01). A significant correlation was found between the change in responsiveness to AMP induced by repeated challenge and the attenuation of the subsequent exercise response (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)