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The motility of the bile ducts of the pigeon and the effects of autonomic drugs on it were studied in vivo and in vitro. Peristalses which originated rhythmically at the hepatic end of the duct propagated to the duodenal end and excreted the bile into it. Antiperistalses did not occur in vivo. The intervals of peristalses of the duct in vivo changed variably while those of the spontaneous contractions in the isolated duct were fairly constant. No synchronization between the electrical activities recorded at the duodenal end of the duct and the duodenum close to the duct was observed. Cholinergic drugs increased motilities of the duct and duodenum. Adrenaline, noradrenaline and phenylephrine induced the excitation of the duct and isoprenaline slight inhibition. All of these sympathomimetic drugs inhibited duodenal motility. The excitatory effect was abolished by alpha-adrenergic blocking agent, and the inhibitory one was abolished by alpha- and/or beta- adrenergic blocking agents. These results suggest that the bile duct is functionally independent of the duodenum and responsibility of the adrenergic drugs are different between two organs.

The isolated bile duct preparations, which contain the duodenal circular muscle, and the proper bile duct muscle preparations in the dolphin (Stenella caeruleoalbus) were used and their longitudinal motilities were recorded by means of strain gauge transducer. 1. Raising the intraluminal pressure produced the augmentation of the motility of the bile duct preparation. 2. Acetylcholine and carbamylcholine caused the increase of the motility of the bile duct preparations. After atropinization the excitatory response was completely abolished. 3. Adrenaline caused the inhibitory response more predominantly than the excitatory one in the bile duct preparations, while in the proper bile duct muscle preparations it induced the excitatory response more predominantly than the inhibitory one. Phenylephrine produced mainly the excitatory effect in both preparations, while isoprenaline did chiefly the inhibitory one. These experimental results suggest that activation of alpha- and beta-adrenergic receptors in the bile duct muscle causes the excitatory and inhibitory responses, respectively. 4. Transmural electric stimulation induced both excitatory and inhibitory responses in the bile duct preparation. The former response was abolished after atropinization, while the latter one was not. It may be, therefore, suggested that the excitatory response was induced by stimulation of cholinergic neurons, while the inhibitory one was produced by that of the adrenergic fibers and non-adrenergic inhibitory neurons.