Inhibition of Enzyme Secretion and Autophagy of Secretory Granules Caused by Action of High Concentration of Secretory Hormones on Rat Pancreatic Slices

This chapter discusses the inhibition of enzyme secretion and autophagy of secretory granules caused by action of high concentration of secretory hormones on rat pancreatic slices. Secretagogues at high concentration cause inhibition of pancreatic enzyme secretion, which does not occur at the receptor level. The supraoptimal concentration of secretagogues causes morphological changes at the luminal area, which eventually collapses, and the lumen becomes filled with secretory material. The second phenomenon observed in pancreatic slices in the presence of high concentration of secretagogues is the activation of the lysosomal system concomitant with myocardial depressant factor (MDF) production and release to the medium. The lysosomal system, which is activated by the high concentration of secretagogues, takes up secretory granules to form autophagic vacuoles, resulting in MDF production. The supraoptimal concentration of secretagogues increases the intracellular level of calcium that in turn causes disaggregation and disruption of the filamentous system.