Digital image analysis with fura-2 was made to investigate early stage of secretagogue-induced [Ca2+], increase in pancreatic acinar cells. When isolated acini dissociated with collagenase were stimulated with l0 pM CCK-8 or l0 nM ACh, the initial rise in [Ca2+], occurred in the region beneath the basolateral plasma membrane. When the acinar cells isolated with collagenase, trypsin and EGTA were stimulated with 1 mM ACh, the rise started at the luminal region. Morphological deteriorations were

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... etected in the latter preparation. Possible causes for the opposite [Ca2+], gradient may be in procedures of isolation, destruction of acinar constitution, and composition of perifusing solution.