The kinetics of synaptic vesicle reacidification at hippocampal nerve terminals.

TitleThe kinetics of synaptic vesicle reacidification at hippocampal nerve terminals.
Publication TypeJournal Article
Year of Publication2006
AuthorsAtluri PP, Ryan TA
JournalJ Neurosci
Date Published2006 Feb 22
KeywordsAnimals, Animals, Newborn, Cells, Cultured, Electric Stimulation, Endocytosis, Hippocampus, Hydrogen-Ion Concentration, Kinetics, Neuronal Plasticity, Neurons, Presynaptic Terminals, Rats, Rats, Sprague-Dawley, Synaptic Transmission, Synaptic Vesicles

After exocytosis, synaptic vesicles are recycled locally in the synaptic terminal and are refilled with neurotransmitter via vesicular transporters. The biophysical mechanisms of refilling are poorly understood, but it is clear that the generation of a proton gradient across the vesicle membrane is crucial. To better understand the determinants of vesicle refilling, we developed a novel method to measure unambiguously the kinetics of synaptic vesicle reacidification at individual synaptic terminals. Hippocampal neurons transfected with synapto-pHluorin (SpH), a synaptic vesicle-targeted lumenal GFP (green fluorescent protein), whose fluorescence is quenched when protonated (pKa approximately 7.1), were rapidly surface-quenched immediately after trains of repetitive electrical stimulation. The recently endocytosed alkaline pool of SpH is protected from such surface quenching, and its fluorescence decay reflects reacidification kinetics. These measurements indicate that, after compensatory endocytosis, synaptic vesicles reacidify with first-order kinetics (tau approximately 4-5 s) and that their rate of reacidification is subject to slowing by increased external buffer.

Alternate JournalJ. Neurosci.
PubMed ID16495458
Grant ListR01 NS036942 / NS / NINDS NIH HHS / United States