The effects of Ca++ on release of amylase by mouse pancreas in vitro were studied. The cholinergic agonist bethanechol increased release of amylase in a parallel manner in both normal and O Ca++ medium; however, release at all concentrations of bethanechol was depressed about 50% in O Ca++ medium. When pancreatic fragments were superfused with O Ca++ medium, bethanechol still produced a normal stimulation of amylase release after half of the total tissue Ca++ was washed out. This Ca++ loss included both extracellular and some intracellular Ca++. Uptake and equilibration of 45Ca++ into pancreatic fragments was multiphasic, with total equilibration with stable Ca++ still not reached after 3 hr. Addition of bethanechol had no effect on the rate of 45Ca uptake and equilibration. 45Ca++ efflux was not influenced by superfusion in O Ca++ medium, while the stimulation of 45Ca++ efflux by bethanechol was enhanced. It is concluded that extracellular Ca++ and/or Ca++ influx is not of major importance in triggering pancreatic enzyme release, but that extracellular Ca++ may regulate the release process thus accounting for the parallel changes in unstimulated and stimulated amylase release.
|Original language||English (US)|
|Title of host publication||American Journal of Physiology|
|Number of pages||4|
|State||Published - 1975|
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