ARTICLE Multivesicular exocytosis in rat pancreatic beta cells

Aims/hypothesis To establish the occurrence, modulation and functional significance of compound exocytosis in insulin-secreting beta cells. Methods Exocytosis was monitored in rat beta cells by electrophysiological, biochemical and optical methods. The functional assays were complemented by three-dimensional reconstruction of confocal imaging, transmission and block face scanning electron microscopy to obtain ultrastructural evidence of compound exocytosis. Results Compound exocytosis contributed marginally (<5% of events) to exocytosis elicited by glucose/membrane depolarisation alone. However, in beta cells stimulated by a combination of glucose and the muscarinic agonist carbachol, 15–20 % of the release events were due t