Table I.

Proportion of all exocytic events attributable to sequential exocytosis under various experimental conditions

Proportion of sequential exocytosis
ConditionExocytosisEn face eventsaTotal eventsa
events cell−1 min−1%%
Acinar cells
100 pM cholecystokinin>50>50
Islet cells
20 mM glucose11.22.6 (77)1.9 (693)
20 mM glucose + 2 μM forskolin26.72.4 (84)1.0 (964)
20 mM glucose + 400 nM PMA44.82.0 (51)2.3 (651)
20 mM glucose (35°C)21.51.9 (92)3.6 (388)
20 mM glucose + 2 μM forskolin (35°C)454.5 (224)
20 mM glucose + 400 nM PMA (35°C)403.9 (102)
60 mM KCl18.81.3 (521)
100 μM acetylcholine6.81.2 (243)
NP-EGTA48.62.4 (83)3.3 (563)
20 mM glucose + 2 μM forskolin
 (15 mM methyl-β-cyclodextrin)4.88.9 (416)
  • a Numbers in parentheses refer to the number of events analyzed.

  • The data for acinar cells are from Nemoto et al. (2001). The contribution of sequential exocytosis to total exocytic events was significantly different from the value (2.6%) for en face events during glucose stimulation only in methyl-β-cyclodextrin–treated preparations (χ2 test, P < 0.01).