In pancreatic acini, administration of the phospholipase C inhibitor, U-73122, abolished Ca²⁺ oscillations and amylase secretion induced by CCK but had much less effect on the action of CCK analog JMV-180. In contrast, the phospholipase A₂ inhibitor, ONO-RS-082, inhibited both Ca²⁺ spikes and amylase secretion induced by JMV-180, but it had little effect on the action of CCK-8. Both arachidonic acid (AA) and a cytochrome P-450 inhibitor, SKF-96365, generated Ca²⁺ spikes from the agonist-sensitive pool. AA was capable of releasing Ca²⁺ from the endoplasmic reticulum (ER), suggesting the direct Ca²⁺ releasing pathway. There is no evidence of Ca²⁺-induced Ca²⁺ release (CICR) since neither caffeine, a CICR potentiator, nor ryanodine, a CICR inhibitor, modulated agonist-induced Ca²⁺ oscillations and Ca²⁺ release from the ER. On the contrary, increasing concentrations of caffeine abolished agonist-induced Ca²⁺ spikes. Therefore we have demonstrated that depending on the agonists used, CCK receptor activation may result in the differential involvement of the phosphoinositol and arachidonic acid pathways to mediate calcium oscillation and amylase secretion.