In‐Vitro Motility Studies on the Canine and Human Extrahepatic Biliary Tracts

The spontaneous and stimulated in vitro activity of the common bile duct, the sphincter, choledochus and the gallbladder of the dog, the in vitro activity of the common bile duct of man and the histological appearances of canine and human common bile ducts were studied. All parts of the extrahepatic biliary tract exhibited spontaneous activity and were stimulated by acetylcholine, acetyl beta‐methyl‐choline, noradrenaline tartrate, adrenaline tartrate, isoprenaline hydrochloride and 5‐hydroxy‐tryptamine. Morphine sulphate was found to be a weak stimulant of the biliary tract in vitro. Histological examination of the common bile duct in both man and dog showed the presence of small amounts of smooth muscle, maximal in quantity near the duodenum and minimal at the hepatic end, and arranged chiefly in a longitudinal direction. The results suggest that the common bile duct, along with the gallbladder and sphincter choledochus, has a role in the dynamics of the extrahepatic biliary tract of both man and dog.