Intrinsic asthma, not associated with allergic responsiveness, provides an opportunity to study non immune pathways in asthma and to test the hypothesis that exercise precipitates bronchospasm in susceptible subjects by mechanically inducing mediator release from peribronchial mast cells. Sixteen subjects with extrinsic asthma and 9 with intrinsic asthma were studied. Four to 6 times at 2 to 3 day intervals, each subject performed 5 minutes of treadmill exercise adequate to raise heart rate to 90 to 95% of maximum predicted for age. VC, FEV1, and MMEFR were measured prior to exercise and at 1, 5, 10, 15 and 20 minutes after exercise. Thirteen of the 16 extrinsic asthmatics had over 20% fall in FEV1 on at least 1 run, while only 3 or 9 intrinsic asthmatics did. Extrinsic asthmatics responded to exercise with more bronchospasm during a significant pollen season. It is concluded that there is significantly less airway response to exercise in intrinsic asthmatics, reflecting the importance of mediator release in exercise induced asthma.
|Original language||English (US)|
|Number of pages||1|
|State||Published - Jan 1 1975|
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