Figure 5. Effects of Ca²⁺-free solution and a Ca²⁺ channel blocker on exocytotic events and cell shrinkage evoked by 10 μM ACh.

V/V₀ is denoted by ○, and the frequency of exocytotic events is denoted by •. A, Ca²⁺-free solution evoked shrinkage in unstimulated antral mucous cells. Subsequent ACh stimulation evoked transient cell shrinkage, but did not activate exocytotic events (n = 6). B, Ni²⁺ also evoked cell shrinkage in unstimulated antral mucous cells. ACh stimulation subsequent to the addition of Ni²⁺ evoked both exocytotic events and cell shrinkage (n = 4). However, both the frequency of exocytotic events and the extent of cell shrinkage were reduced compared with those in control experiments.