Sphincteric mechanism of the main pancreatic duct in the dog. An experimental model of the isolated sphincteric preparation.

This study describes an in vitro experimental model of the sphincter at the lower end of the main pancreatic duct in the dog. This model, employing a drop counter to measure the drop rate, monitors the perfusion rate of Tyrode through the sphincter. Acetylcholine (ACh), employed to establish the sensitivity and viability of the isolated sphincter, produced a contraction of the sphincter which was concentration-response related. Saline, as a control, atropine and hexamethonium did not affect the drop rate. Atropine (20 microgram) partially abolished the contraction produced by 50 microgram of ACh; hexamethonium (50 microgram) did not have an effect. Caerulein 50 microgram produced a relaxation of the sphincter; adrenaline 50 microgram a contraction. Both sympathetic and parasympathetic mechanisms seem to play a role in the regulation of sphincteric activity of the main pancreatic duct in dogs.