Choledochal cyst. Its possible autonomic involvement in the bile duct.

The properties of the choledochal cyst were compared with those of the normal common bile duct. Cholecystokinin-octapeptide and a high concentration of acetylcholine produced smaller contractions in the strips of the narrow portion of the cyst than in the strips of the dilated portion and the normal common bile duct. Nicotine did not cause contractions in the strip of the narrow portion of the cyst. gamma-Aminobutyric acid (GABA) induced atropine-sensitive, tetrodotoxin-sensitive contractions in the bile ducts through bicuculline-sensitive, furosemide-sensitive GABAA receptors located on the postganglionic cholinergic neuron. The GABA did not induce contractions in the narrow portion of the cyst. The number of ganglion cells was decreased markedly in the same portion. These findings suggest that the choledochal cyst has postganglionic neural dysfunction. This character may be one of the causes of cyst formation.