Effect of nedocromil sodium on bronchoconstriction induced by adenosine and tachykinins.

Purines and neuropeptides may act as neurotransmitters of the local axon reflex in the airways. Nedocromil sodium has been shown to inhibit adenosine- and neurokinin A-induced bronchoconstriction both in the rat and in man. In this study we used the rat model for further investigation of the mechanism of action of nedocromil sodium in the adenosine- and neurokinin A-challenge. The animals were challenged intravenously, and immediately after maximal bronchoconstriction a bronchoalveolar lavage was performed and histamine was assayed in the supernatant of the lavage fluid. Nedocromil sodium significantly inhibited the adenosine- and the neurokinin A-induced increase in histamine concentration in the lavage fluid. Nedocromil sodium had no influence on the airway responsiveness to serotonin or carbachol. We therefore concluded that the inhibitory effect of nedocromil sodium on adenosine- and neurokinin A-induced bronchoconstriction can be explained by its activity on airway mast cells.