[Pharmacological studies on terminal biliary duct with particular reference to effects of prostaglandins and a few other drugs (author's transl)].

Numerous studies have been reported on the roles of the terminal portion of biliary duct in the mechanism of bile excretion. There is as yet no generally agreed conclusion as to functional independence of terminal biliary duct, however. The present study has been performed in rabbits to investigate the effects of prostaglandins and a few other drugs on the terminal portion of common bile duct, with the results leading to the following conclusions: 1) The group of muscles comprising the terminal biliary duct of rabbit intercommunicate with the duodenal longitudinal muscle and no histologic evidence has been observed for the presence of any independent sphincter in this portion. 2) The terminal biliary duct and the adjoining segment of the duodenum display practically the same attitudes on electromyograms. 3) The internal pressures of the duodenum and common bile duct were noted to show changes coinciding with electric discharges in the duodenum or terminal biliary duct, respectively, and not to affect each other. 4) The interrelations observed between discharge and flow rate or internal pressure of the terminal biliary duct indicate that the muscles of this portion possess the function as sphincter. It is suggested, therefore, that bile excretion into the duodenal lumen is effected primarily by relaxation of the terminal biliary duct. 5) Prostaglandin E2 has proven to behave differently toward discharges in the duodenum and terminal biliary duct, viz., facilitation in the former and inhibition in the latter. It would follow that these structures serve mutually independent functions. 6) The effects of prostaglandins on the duodenum and the terminal portion of common bile duct are considered to stem from their direct actions on the musculatures of these regions. 7) The findings stress importance of observations with biologically active substances in tissues in the study aimed at clarification of the biliary excretory function.