Article abstract
Nature Neuroscience 10, 196 - 205 (2007)
Published online: 14 January 2007 | doi:10.1038/nn1839
Presynaptic Ca2+ buffers control the strength of a fast post-tetanic hyperpolarization mediated by the 
3 Na+/K+-ATPase
Jun Hee Kim1, Igor Sizov2, Maxim Dobretsov2 & Henrique von Gersdorff1
Abstract
The excitability of CNS presynaptic terminals after a tetanic burst of action potentials is important for synaptic plasticity. The mechanisms that regulate excitability, however, are not well understood. Using direct recordings from the rat calyx of Held terminal, we found that a fast Na+/K+-ATPase (NKA)-mediated post-tetanic hyperpolarization (PTH) controls the probability and precision of subsequent firing. Notably, increasing the concentration of internal Ca2+ buffers or decreasing Ca2+ influx led to larger PTH amplitudes, indicating that an increase in [Ca2+]i regulates PTH via inhibition of NKAs. The characterization for the first time of a presynaptic NKA pump current, combined with immunofluorescence staining, identified the 
3-NKA isoform on calyx terminals. Accordingly, the increased ability of the calyx to faithfully fire during a high-frequency train as it matures is paralleled by a larger expression of 3-NKA during development. We propose that this newly discovered Ca2+ dependence of PTH is important in the post-burst excitability of nerve terminals.
- The Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
- Department of Anesthesiology, University of Arkansas for Medical Sciences, 4301 Weat Markham Street, Little Rock, Arkansas 72205, USA.
Correspondence to: Henrique von Gersdorff1 e-mail: vongersd@ohsu.edu
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