Abstract
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 α-excitatory and β-inhibitory 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 a and p-blockade or a combination of both. Sympathomimetic amines caused contraction and relaxation on the common bile duct of rabbits. Transmural stimulation to guineapig gallbladder and rabbit common bile duct is mediated by cholinergic and adrenergic nerves. α-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.
