Exocrine pancreatic secretion and immunoreactive secretin release after repeated intraduodenal infusions of bile in man.

The exocrine pancreatic secretion of water, bicarbonate, amylase, trypsin, chymotrypsin, and lipase and the plasma concentration of immunoreactive secretin (IRS) were studied before and after repeated intraduodenal infusions of cattle bile in man. After endoscopic cannulation of the main pancreatic duct, juice was collected in 5-min samples for 20 min. A solution of 6 g dried cattle bile in 60 ml water was then infused into the duodenum through a separate catheter attached to the outside of the duodenoscope. Juice was collected for another 20 min. After this period a solution of 6 g dried cattle bile in 40 ml water was infused into the duodenum, and juice again collected for 20 min. Blood was frequently drawn from an arm vein for estimation of plasma concentration of secretin by radioimmunoassay. Both bile infusions caused significant rises in flow rate, bicarbonate concentration and output, and IRS (p less than 0.05). Enzyme concentrations decreased significantly after intraduodenal bile infusions (p less than 0.05). Outputs of enzymes rose significantly after the first bile infusion; however, a rise after the second bile infusion was found only for amylase. Further, a significant decrease in amylase and lipase concentration was found after the second bile infusion. The findings indicate that the increase in proteolytic enzyme and lipase secretion was due to a washout phenomenon. The increase in the plasma concentration of secretin after repeated bile infusions, with a corresponding effect on flow rate and bicarbonate secretion, indicates that secretin may be the main factor responsible for the exocrine pancreatic secretion caused by intraduodenal bile infusions.