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Nature. 1992 Mar 5;356(6364):60-3.

Delay in vesicle fusion revealed by electrochemical monitoring of single secretory events in adrenal chromaffin cells.

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1
Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.

Abstract

In synapses, a rise in presynaptic intracellular calcium leads to secretory vesicle fusion in less than a millisecond, as indicated by the short delay from excitation to postsynaptic signal. In nonsynaptic secretory cells, studies at high time resolution have been limited by the lack of a detector as fast and sensitive as the postsynaptic membrane. Electrochemical methods may be sensitive enough to detect catecholamines released from single vesicles. Here, we show that under voltage-clamp conditions, stochastically occurring signals can be recorded from adrenal chromaffin cells using a carbon-fibre electrode as an electrochemical detector. These signals obey statistics characteristic for quantal release; however, in contrast to neuronal transmitter release, secretion occurs with a significant delay after short step depolarizations. Furthermore, we identify a pedestal or 'foot' at the onset of unitary events which may represent the slow leak of catecholamine molecules out of a narrow 'fusion pore' before the pore dilates for complete exocytosis.

PMID:
1538782
DOI:
10.1038/356060a0
[Indexed for MEDLINE]
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