Atropine, sodium cromoglycate, and thymoxamine in PGF2 alpha-induced bronchoconstriction in extrinsic asthma.

In six patients with extrinsic bronchial asthma the inhalation of prostaglandin (PG) F2 alpha in a small dosage produced significant bronchoconstriction, whereas PGE2 produced bronchodilatation. In these patients cholinergic blockade with atropine partially inhibited the PGF2 alpha-induced bronchoconstriction, but the alpha-receptor-blocking drug thymoxamine and sodium cromoglycate did not. These results suggest that the effect of PGF2 alpha is mediated through cholinergic receptors in the airways, and this effect is grossly exaggerated in asthma. The failure to inhibit PGF2 alpha-induced bronchoconstriction with sodium cromoglycate and the observation of an inhibitory effect of sodium cromoglycate in both allergic and exercise asthma suggest that locally formed PGF2 alpha may not be the main factor in the pathogenesis of bronchial asthma.