Mechanisms determining the time course of secretion in neuroendocrine cells.
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.
Chow
R H
RH
Max Planck Institute for Biophysical Chemistry, Department of Membrane Biophysics, Goettingen, Germany.
Klingauf
J
J
Heinemann
C
C
Zucker
R S
RS
Neher
E
E
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
D002021:Buffers; D002614:Chelating Agents; D009761:Nystatin; D002118:Calcium; D016257:Fura-2