GABA evoked ACH release from isolated guinea pig ileum.

To identify the target cells of GABAergic neurons located in the myenteric plexus, the action of gamma-aminobutyric acid (GABA) on the release of acetylcholine (ACh) and on the contractions was studied using the isolated guinea pig ileum. GABA evoked a release of 3H-ACh from the contracting ileum, under conditions of loading with 3H-choline. As both the GABA-evoked release of 3H-ACh and the contractions were inhibited by bicuculline, tetrodotoxin and furosemide, but not by hexamethonium, this release seems to be evoked through GABA receptors which are bicuculline sensitive and associated with the Cl- ion channel.