AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 1 7-11, Copyright © 1988 by American Physiological Society
Release of secretin along the canine small intestine
M. Fried, A. S. Fink, L. R. DeSouza, C. Beglinger, K. Gyr and J. H. Meyer
Gastroenterology Service, Sepulveda Veterans Administration Medical Center, Los Angeles, California.
The profile of secretin release along the entire canine small intestine was
examined in this study. Four equal loops of the small gut, from the
duodenal bulb to the ileocoecal valve, were isolated. In eight anesthetized
dogs the four segments were perfused for 40 min each in random order with
an acidified (pH 2.5) emulsion of 20 mM oleic acid. In four dogs control
experiments were performed using 0.15 M saline. Secretin release in portal
venous blood was measured by a sensitive radioimmunoassay. Although
secretin was mainly released in the first quarter of the small intestine
(310 pM X 40 min), large amounts of secretin, 33% of the total secretin
release, were liberated in the second quarter of the small intestine (164
pM X 40 min). Minute amounts of secretin (23 pM X 40 min) were released in
the third quarter, whereas perfusion of the last quarter of the small gut
failed to release secretin. We conclude that the major portion of secretin
is releasable in the first quarter of the small gut. High amounts of
secretin can be liberated in the second quarter of intestine, an area that
is probably never exposed to pH below 4.5 (the known threshold for secretin
release by acid), but is still exposed to fatty acids (other releasers of
secretin).
