FIGURE 12. Regulation of exocytosis.


Regulation of exocytosis. Digestive enzymes are stored in zymogen granules at the apical surface of the acinar cell. Regulated secretion occurs through exocytosis stimulated by neurohumoral agents. These agents include gastrin-releasing peptide (GRP), cholecystokinin (CCK), acetylcholine (Ach), secretin and vasoactive intestinal polypeptide (VIP). Each acts to mediate secretion through interacting with its specific receptor. For example, specific interaction of CCK with its receptor (CCK1 receptor) leads to activation of intracellular signaling systems that mediate the exocytosis response. Interactions of GRP, CCK and Ach with their receptors leads to changes in intracellular which, in turn, mediates exocytosis. On the other hand, secretin and VIP increase intracellular cAMP which, in turn, mediates the exocytosis response. Of note, an increase in both calcium and cAMP simultaneously results in synergistic response. That is, the response with both is greater than the expected additive effect. Adapted from Gorelick F, Pandol, SJ, Topazian M. Pancreatic physiology, pathophysiology, acute and chronic pancreatitis. Gastrointestinal Teaching Project, American Gastroenterologic Association. 2003.

From: Digestive Enzymes

Cover of The Exocrine Pancreas
The Exocrine Pancreas.
Pandol SJ.
San Rafael (CA): Morgan & Claypool Life Sciences; 2010.
Copyright © 2011 by Morgan & Claypool Life Sciences.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.