Extracellular magnesium regulates acetylcholine-evoked amylase secretion and calcium mobilization in rat pancreatic acinar cells.

Application of ACh (10(-6) M) to the isolated rat pancreas elicited large increases in amylase secretion, radiolabelled 45Ca influx and cytosolic free Ca2+ levels in zero and normal (1.1 mM) extracellular magnesium (Mg2+). Elevated (10 mM) Mg2+ significantly (P less than 0.001) reduced the ACh-induced amylase output and Ca2+ mobilization. Similarly, ACh (10(-5) M) caused a transient increase in 45Ca efflux from pre-loaded pancreatic segments in normal Mg2+ compared with the much reduced effect in elevated Mg2+. The results suggest that a modification in Mg2+ influences ACh-evoked amylase secretion by regulating Ca2+ mobilization.