Isolated rat pancreatic acinar cells were used to investigate the effect of basic fibroblast growth factor (bFGF) on both amylase secretion and intracellular free calcium concentration ([Ca2+]i) in response to the calcium-mobilizing secretagogue cholecystokinin-octapeptide (CCK-8). Our data show that bFGF inhibited CCK-8-induced amylase release in a concentration-dependent manner and decreased the CCK-8-induced rise in [Ca2+]i. This inhibitory effect of bFGF on both amylase secretion and [Ca2+]i increase in response to CCK-8 was reverted when acinar cells were pretreated with 100 microM tyrphostin A25, a tyrosine kinase inhibitor. Tyrphostin A25 also inhibited Ca2+ influx induced by CCK-8. These results show that bFGF inhibits CCK-8-induced pancreatic response by a tyrosine kinase-dependent mechanism. A role for tyrosine phosphorylation in capacitative Ca2+ entry is suggested.