Calcium causes the biphasic dose-response curve for pancreatic amylase secretion.

High concentrations of bethanechol (10(-4) to 10(-3) M) were effective stimulants of amylase secretion from the mouse pancreas if incubations are performed in low [Ca2+] (0.1 mM) solutions but not if normal Krebs solution (2.56 mM Ca2+) was used. This inhibitory effect of Ca2+ at high secretagogue concentrations did not appear to be mediated through the microtubules or microfilaments.