Agonist-induced cytosolic Ca2+ (Ca2+(i)) signals begin as apical-to- basal Ca2+(i) waves in pancreatic acinar cells and in other polarized epithelia. However, the basis of this polarized Ca2+(i) signaling pattern is unknown. Here we use immunocytochemistry to demonstrate that the type 3 inositol trisphosphate receptor is localized to the extreme apex of pancreatic acinar cells, the region which corresponds to the trigger zone from which Ca2+(i) signals originate in this cell type (Kasai, H., Li, Y. X., and Miyashita, Y. (1993) Cell 74, 669-677). We also show that inositol trisphosphate-mediated Ca2+ release induces amylase release from permeabilized pancreatic acini. Since Ca2+(i) signals begin by inositol trisphosphate-mediated Ca2+ release, these findings suggest that localization of the type 3 inositol trisphosphate receptor to the trigger zone is responsible for the generation of apical-to-basal Ca2+(i) waves, and that this organization may be important for regulating apical exocytosis in pancreatic acinar cells.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|State||Published - Jan 1 1994|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology