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

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