Calcium-triggered exocytosis and endocytosis in an isolated presynaptic cell: Capacitance measurements in saccular hair cells

Thomas D. Parsons, David Lenzi, Wolfhard Almers, William M. Roberts

Research output: Contribution to journalArticle

208 Scopus citations

Abstract

Depolarization of isolated frog saccular hair cells caused Ca2+-dependent increases in membrane capacitance that we interpret as the fusion of synaptic vesicles with the plasma membrane. During a maintained depolarization to -10 mV, the capacitance increased at a rate corresponding to the fusion of ∼500 vesicles per second at each active zone. Release continued at this high rate for up to 2 s, long enough to exhaust >5 times the number of vesicles initially in close apposition to the plasma membrane at active zones. We therefore propose that hair cells are specialized for rapid replenishment of vesicles at release sites. Upon repolarization to -70 mV, the capacitance returned exponentially (time constant, ∼14 s) to near the prestimulus level in perforated-patch recordings, but not in whole-cell recordings, suggesting that a mobile intracellular factor is required for membrane retrieval.

Original languageEnglish (US)
Pages (from-to)875-883
Number of pages9
JournalNeuron
Volume13
Issue number4
DOIs
StatePublished - Oct 1994

ASJC Scopus subject areas

  • Neuroscience(all)

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