Adaptation of Ca(2+)-triggered exocytosis in presynaptic terminals.


Journal Article

Rapid increases in Ca2+ concentration, produced by photolysis of caged Ca2+, triggered exocytosis in squid nerve terminals. This exocytosis was transient in nature, decaying with a time constant of approximately 30 ms. The decay could not be explained by a decline in presynaptic Ca2+ concentration, depletion of synaptic vesicles, or desensitization of postsynaptic receptors. Experiments in which Ca2+ was increased either in a series of steps or continuously at different rates suggested that the decay is caused by adaptation of the exocytotic Ca2+ receptor to higher levels of Ca2+. This adjustable sensitivity to Ca2+ represents a novel property of the triggering mechanism that can be used to evaluate molecular models of exocytosis. Adaptation can limit the amount of transmitter released by a nerve terminal and permit the speed of a presynaptic Ca2+ rise to serve as a critical determinant of synaptic efficacy.

Full Text

Cited Authors

  • Hsu, SF; Augustine, GJ; Jackson, MB

Published Date

  • September 1996

Published In

Volume / Issue

  • 17 / 3

Start / End Page

  • 501 - 512

PubMed ID

  • 8816713

Pubmed Central ID

  • 8816713

Electronic International Standard Serial Number (EISSN)

  • 1097-4199

International Standard Serial Number (ISSN)

  • 0896-6273

Digital Object Identifier (DOI)

  • 10.1016/s0896-6273(00)80182-8


  • eng