Fig. 3. [Ca²⁺]i dynamics in ducts and acini in response to the consecutive application of CCh and ATP in the presence or absence of extracellular Ca²⁺. (A) Transmitted light image. (B) Fluorescence image. Ductal area (red) and acinar area (blue) were selected and measured. The application protocol was as follows: (C) CCh in the absence of extracellular Ca²⁺. (D) CCh in the presence of extracellular Ca²⁺. (E) ATP in the absence of extracellular Ca²⁺. (F) ATP in the presence of extracellular Ca²⁺. Arrows denote the application time of each reagent.