Intracellular Ca2+ in pancreatic acinar cells: Regulation and role in stimulation of enzyme secretion

Evidence for a primary role for intracellular Ca²⁺ in the stimulation of pancreatic enzyme secretion is reviewed. Measurements of cytoplasmic free Ca²⁺ concentration have allowed direct demonstration of its importance in triggering enzyme secretion and defined the concentration range over which membrane Ca²⁺ pumps must work to regulate intracellular Ca²⁺. Current evidence suggests a key role for the Ca²⁺ Mg-ATPase of rough endoplasmic reticulum in regulating intracellular Ca²⁺ and accumulating a Ca²⁺ store which is released by the action of inositol-l,4,5 trisphosphate following stimulation of secretion.Abbreviations Used EGTA (ethylene dioxy) diethylene-dinitrilotetraacetic acid - BAPTA 1,2-bis (2-aminophenoxy) ethane NNN,N-tetracetic acid - InsP₃ inositol trisphosphate - Ins-1,4,5P₃ and Ins-1,3,4P₃ isomers of inositol trisphosphate with the position of phosphate groups assigned - Ins-1,3,4,5P₄ inositol tetrakisphosphate