LOCAL AND GLOBAL CYTOSOLIC CA-2+ OSCILLATIONS EVOKED BY AGONISTS AND INOSITOL TRISPHOSPHATE

The agonists acetylcholine (ACh) and cholecystokinin (CCK) evoke oscil lating cytosolic Ca2+ signals in pancreatic acinar cells. Low agonist concentrations evoke local cytosolic Ca2+ spikes confined to the secre tory pole region and intracellular inositol trisphosphate application can mimick this action. These spikes can occur alone, repetitively or precede longer lasting Ca2+ transients that spread throughout the cell . ACh and CCK evoke different Ca2+ signal patterns also influenced by the resting cytosolic Ca2+ concentration ([Ca2+]i). Ca2+ pump-mediated Ca2+ extrusion occurs in a pulsatile manner and is synchronous with t he transient elevations of [Ca2+]i.