Comparison of acetylcholine sensitivity in asthmatics with negative and positive response to exercise

Airways response to inhaled acetylcholine was studied in asthmatic patients with negative and positive response to exercise. The respiratory threshold of acetylcholine proved to be lower in exercise-responders. Mean value of the bronchoconstrictive dose of acetylcholine was found 72 +/- 78 micrograms in patients with positive, while 510 +/- 360 micrograms in those with negative response to exercise challenge. Our data seem to confirm previous hypotheses, i.e. that exercise-induced asthma is a phenomenon dependent on two factors: mediators generated during exercise (histamine, catecholamines, neutrophil chemotactic factor) and a vagal response from the bronchi.