Characteristics and mechanism of enzyme secretion and increase in Ca^(2+)_i in Saikosaponin.(I)stimulated rat pancreatic acinar cells

摘要

AIM:This investigation was to reveal the characteristics and mechanism of enzyme secretion and increase in [Ca^2+]i stimulated by saikosaponin(1)[SA(1)] in rat pancreatic acini.METHODS:Pancreatic acini were prepared from male Wistar rats.Isolated acinar cells were suspended in Eagle's MEM solution,After adding drugs,the incubation was performed at 37℃for a set period of time.Amylase of supermatant was assayed using starch-iodide reaction.Isolated acinar single cell was incubated with Fura-2/AM at 37℃,then cells were wasthed and resuspended in fresh sulution and attached to the chamber,Cytoplasm [Ca^2+]i of a single cell was expressed by fluorescence ratio F340/F380 recorded in a Nikon PI Cd^2+ measurement system.RESULTS:Rate course of amylase secretion stimulated by SA(I) in rat pancreatic acini appeared in bell-like shape,The peak amplitude increased depended on SA(I) concentration.The maximum rate responded to 1^10moll/L SA(I) was 13.1-forld of basal and the rate decreased to basal level at 30min.CCK-8 receptor antagonist Bt2-cGMP markedly inhibited amylase secretion stimulated by SA(I)and the dose-effect relationship was similar th that by CCK-8,[Ca^2+]i in a single acinar cell rose to the peak at 5min afer adding 5×10^-6mol/L SA(I) and was 5.1-fold of basal level.In addition,there was a secondary increase after the initial peak.GDP could inhibit both the rate of amylase secretion and rising of [Ca^2+]i stmulated by SA(I) in a single pancreatic acinar cell.