Agonist-induced changes in cell shape during regulated secretion in rat pancreatic acini

The actin cytoskeleton plays an important role in the mediation of exocytos is and the determination of cell shape. Experimentally induced changes in c ell shape have been shown to affect stimulated secretion in pancreatic acin i. In this study, we have examined whether physiologic agonists induce chan ges in acinar cell shape to modulate secretion. Computer-enhanced video mic roscopy, immunofluorescence confocal microscopy, and quantitative Western b lotting were used to study cell shape changes and cytoskeletal dynamics in rat pancreatic acini. Amylase assays were performed to study the effect of the actin-myosin cytoskeletal antagonists latrunculin A, BDM, and ML-9 on s ecretion. We found that pancreatic acini underwent a prominent and reversib le shape change in response to the physiologic secretory agonist cholecysto kinin. This was accompanied by an apical activation of myosin II as well as a basolateral redistribution of both actin and myosin II. Cytoskeletal ant agonists inhibited this shape change and attenuated stimulated amylase secr etion. Therefore, in addition to acting as a barrier at the apex, the actin -myosin cytoskeleton may also function to modulate cell shape to further re gulate stimulated secretion. (C) 2000 Wiley-Liss, Inc.