This investigation was to reveal the characteristics and mechanism of enzyme secretion and increase in [Ca2+], stimulated by saikosaponin (I) [SA(I)] 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 supematant was assyayed using starch iodide reaction Isolated acinar single cell was incubated with Fura-2/AM at 37℃, then cells were washed and resuspanded in fresh solution and attached to he chamber Cytoplasm [Ca2+], of a sngle cell was expressed by fluorescence ratio F340/F380 recorded in a Nikon Pl Ca2+ mesurement systm. RESULTS: Rate couse 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 1×10-5mol/L SAC (I) was 13. I-fold of basal and the rate decreased to basal level at 30min CCK-8 receptor antagonist Bt2-cGmp markedly inhibited amylse secretion stimulated by SA (I) and the dose effect relationship was sirrdlar to that by CCK-8[Ca2+]i in a single acinar cell to the peak at 5 min after 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 CDP could inhibit both the rote of amylase secretion and rising of [Ca2+] stimulated by SA (I) in a single pancreatic acinar ce11. CONCLUSION: SA(I)) is highly efficient in promting the secetion of enzymes synthesized in rat pancreatie acini and raising intracellular [Ca2+]i. Signaling transduction pathway of SA (I) involves activating special membrane receptor and increase in cytoplasm [Ca2+]i sequentially