Effects of Extracellular Calcium and Magnesium on Bile-Salt-Stimulated Amylase Release from Rat Pancreatic Acini

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Abstract
The effects of extracellular calcium and magnesium on bile salt-induced amylase release from rat pancreatic acini have been studied. The amylase releases caused by from 0.25 mM to 1.0 mM taurodeoxycholate (TDC) and by taurochenodeoxycholate (TCDC) at a concentration of more than 0.75 mM were reduced by ethylene-diaminetetraacetic acid (EDTA) and increased by verapamil. EDTA and verapamil had no significant effect on the taurocholate (TC) (1.0-5.0 mM)-stimulated amylase release. The inhibiting effect of EDTA began to appear already during the initial 5 min and was not parallel to any change of lactate dehydrogenase release. The TDC- and TCDC-stimulated amylase release was strongly dependent on the concentrations of extracellular calcium and was only weakly dependent on extracellular magnesium. The TC-induced amylase release was slightly increased only at high concentrations of calcium and magnesium. It is suggested that the mechanism of dihydroxy bile salt-induced amylase release from rat pancreatic acini is different from that of trihydroxy bile salt. The dihydroxy bile salt-stimulated amylase release is dependent on extracellular calcium but does not seem to be related to the uptake of calcium by the acini.