Compound 48/80 elicits cholinergic contraction through histamine release in the chick oesophagus.

1. The effects of compound 48/80 on cholinergic nerve transmission and on the liberation of histamine in the isolated chick oesophagus were investigated. 2. Compound 48/80 (0.2-1 microgram ml-1) potentiated the cholinergic nerve-induced contraction and caused the contraction of the oesophagus itself. The latter response was prevented by atropine, tetrodotoxin and mepyramine but not by metiamide. 3. Compound 48/80 released dose-dependently endogenous histamine from the isolated chick oesophagus. 4. These results suggest that the action of compound 48/80 is mediated by the release of histamine from an endogenous pool and that histamine released endogenously facilitates the release of ACh from the intrinsic cholinergic nerve in the chick oesophagus.