[Adrenoceptors and autonomic nerve control mechanisms in the biliary tract]

Effects of sympathomimetics and sympatholitics were studied on the biliary system of guinea-pigs (in vitro) and rabbits (in vitro and in vivo). Contractions and relaxations produced by sympathomimetic amines are mediated by alpha-excitatory and beta-inhibitoray adrenoceptors in the biliary system (gallbladder, common bile duct and sphinctor of oddi) of guinea-pigs. Sympathomimetic amines caused relaxations in the sphincter of oddi in rabbits (in vitro and in vivo) and responses were antagonized by alpha- and beta-blockade or a combination of both. Sympathomimetic amines caused contraction and relaxation on the common bile duct of rabbits. Transmural stimulation to guinea-pig gallbladder and rabbit common bile duct is mediated by cholinergic and adrenergic nerves, alpha-inhibitory adrenoceptor would thus be involved in the postanglionic cholinergic nerve endings in the gallbladder of guinea-pig. No difference was observed in mechanical responses to transmural stimulation in either the isolated sphincter of oddi or the duodenum of rabbits. It is concluded that the guinea-pig biliary system is functionally independent of the gastro-intestinal system and that the rabbit sphincter of oddi is functionally similar to the duodenal wall.