Important basic physiological mechanisms of exocrine pancreas secretio
n were delineated in a canine model. However, dogs have been considere
d unsuitable for the study of the controversial feedback regulation of
exocrine pancreas secretion. The present study reveals a marked modif
ication of pancreas secretion following the intraduodenal instillation
of lipase: The postprandial lipase secretion decreases from 2,421 U x
180 min-1 to 1,490 U x 180 min-1, but simultaneously determined chole
cystokinin (CCK) concentrations in plasma do not increase under these
circumstances. The intraduodenal application of a protease inhibitor (
800 mg camostate) significantly stimulates the secretion of the exocri
ne pancreas in the fasting dog: After 15 min the protein release incre
ased to 133 +/- 30 mg. Intravenous atropine blocks this increase. The
plasma concentrations of CCK are not significantly influenced. These r
esults in our canine model show that the secretory activity of the exo
crine pancreas depends on the intraduodenal enzyme content. CCK is irr
elevant in this context.