SECRETORY VESICLE POOLS AND RATE AND KINETICS OF SINGLE VESICLE EXOCYTOSIS IN NEUROSECRETORY-CELLS

Secretory vesicles are localized in specific compartments within neuro secretory cells. Morphometric, cytochemical and electrophysiological t echniques have allowed the definition of secretory Vesicle compartment s. These are different pools in which vesicles are in various states o f releasability. The transit of vesicles between compartments is not r andom, but an event controlled and regulated by Ca2+ and the cortical F-actin network. Cortical F-actin disassembly, a Ca2+-dependent event, controls the transit of secretory vesicles from the reserve compartme nt to the release-ready vesicle pool. Furthermore, the recent developm ent of new technical approaches (patch-clamp membrane capacitance, ele ctrochemical detection of amines with carbon-fibre microelectrodes) ha s now permitted us to understand the kinetics of single vesicle exocyt osis.