FIGURE 2.

Acetylcholine-induced Ca²⁺ increase in PC12 cells is mediated by cADPR. A, ACh (50 μm), ATP (100 μm), or bradykinin (50 μm) induced a Ca²⁺ increase in PC12 cells as measured by the Ca²⁺ indicator, Fura-2 AM. B, pretreatment of PC12 cells with either 8-Br-cADPR (100 μm), nicotinamide (20 mm), or ryanodine (20 μm) inhibited the ACh-induced Ca²⁺ increase compared with untreated cells. C, inhibition of the ACh-induced Ca²⁺ increase in Fura-2-loaded PC12 cells by either removal of external Ca²⁺ (Ca²⁺-free HBSS with 0.2 mm EGTA), pretreatment with PTX (1 μg/ml) or atropine (10 μm). The graphs represent data from five independent experiments expressed as means ± S.E., n = 20–50 cells.