title: Mechanisms determining the time course of secretion in neuroendocrine cells.
abstract: Transmitter release from chromaffin cells differs from that in synapses in that it persists for a longer time after Ca2+ entry has stopped. This prolonged secretion is not due to a delay between vesicle fusion and transmitter release, nor to slow detection of released substance: step increases in capacitance due to single vesicle fusion precede the release detected by amperometry by only a few milliseconds. The persistence of secretion after a depolarization is reduced by addition of mobile calcium buffer. This suggests that most of the delay is due to diffusion of Ca2+ between channels and release sites, implying that Ca2+ channels and secretory vesicles are not colocalized in chromaffin cells, in contrast to presynaptic active zones.
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Department of Membrane Biophysics, Goettingen, Germany.
authors.forename: R H
authors.initials: RH
authors.lastname: Chow
authors.forename: J
authors.initials: J
authors.lastname: Klingauf
authors.forename: C
authors.initials: C
authors.lastname: Heinemann
authors.forename: R S
authors.initials: RS
authors.lastname: Zucker
authors.forename: E
authors.initials: E
authors.lastname: Neher
mesh_terms: D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002021:Buffers; D002118:Calcium; D002417:Cattle; D002614:Chelating Agents / Q000494:pharmacology; D002838:Chromaffin System / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D004553:Electric Conductivity; D004594:Electrophysiology; D016257:Fura-2 / Q000494:pharmacology; D009761:Nystatin / Q000494:pharmacology; D011930:Reaction Time; D013997:Time Factors
chemical_list: D002021:Buffers; D002614:Chelating Agents; D009761:Nystatin; D002118:Calcium; D016257:Fura-2