EFFECT OF INHALED HEPARIN ON METHACHOLINE-INDUCED BRONCHIAL HYPERREACTIVITY

Although heparin is used as an anticoagulant, its biologic function ha s remained unclear since the 1920s. Glycosaminoglycan heparin possesse s multiple noncoagulant properties, including anti-inflammatory action s, and it is possible that heparin may inhibit airway hyperreactivity. Thus, the purpose of the present investigation was to study the effec t of inhaled heparin on methacholine-induced bronchoconstriction, Thir teen subjects (7 women, 6 men) with mild asthma were included in the s tudy. Bronchial provocation tests were performed in a single-blind, cr ossover, randomized order and repeated 45 min after placebo or aerosol ized heparin inhalation (1,000 U/kg), The heparin inhibited bronchocon striction induced by methacholine. In the methacholine challenge test, heparin treatment resulted in an increase in the mean PD20 over place bo: 5.26 +/- 4.80 mg/mL vs 10.57 +/- 5.72 mg/mL (p<0.0002). These data suggest that inhaled heparin may have an inhibitory role on methachol ine bronchial challenge, possibly via a direct effect on smooth muscle .