Relation of Secretin to the Parasympathetic Mechanism for Pancreatic Secretion

Abstract

By injecting 20 U of secretin intravenously into the anesthetized pancreatic fistula dog every 20 minutes for 2–5 hours, a basal condition is reached in which reproducible amylase and volume outputs are obtained in response to secretin and certain drugs. During the response to large doses of secretin given as a single dose or by continuous intravenous infusion, the administration of pancreozymin, methacholine, Urecholine (bethanacol) or acetylcholine caused an increase in amylase concentration with no increase in volume output. The parasympathomimetic agents produced a slight increase in volume output only when given with small doses of secretin. With large doses of secretin, peripheral stimulation of the vagus above the diaphragm caused either a decrease or no change in the total volume output; amylase concentration was always increased with an adequate stimulus. The same holds for acetylcholine. The record of drops of pancreatic secretion does not always accurately reflect the actual change in volume output. In the pentobarbitalized dog weighing 10 kg 1 µg of methacholine or Urecholine consistently increased the concentration of amylase. Urecholine given alone had only an ecbolic effect.