Sodium channels amplify spine potentials
- Departments of *Howard Hughes Medical Institute and
- †Biological Sciences and
- ‡Chemistry, Columbia University, New York, NY 10027
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Contributed by Kenneth B. Eisenthal, June 11, 2007 (received for review January 25, 2007)
Abstract
Dendritic spines mediate most excitatory synapses in the brain. Past theoretical work and recent experimental evidence have suggested that spines could contain sodium channels. We tested this by measuring the effect of the sodium channel blocker tetrodotoxin (TTX) on depolarizations generated by two-photon uncaging of glutamate on spines from mouse neocortical pyramidal neurons. In practically all spines examined, uncaging potentials were significantly reduced by TTX. This effect was postsynaptic and spatially localized to the spine and occurred with uncaging potentials of different amplitudes and in spines of different neck lengths. Our data confirm that spines from neocortical pyramidal neurons are electrically isolated from the dendrite and indicate that they have sodium channels and are therefore excitable structures. Spine sodium channels could boost synaptic potentials and facilitate action potential backpropagation.
Footnotes
- §To whom correspondence may be addressed. E-mail: kbe1{at}columbia.edu or rmy5{at}columbia.edu
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Author contributions: R.A. and V.N. contributed equally to this work; R.A., V.N., K.B.E., and R.Y. designed research; R.A. and V.N. performed research; R.A., V.N., K.B.E., and R.Y. analyzed data; and R.A., V.N., K.B.E., and R.Y. wrote the paper.
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The authors declare no conflict of interest.
- Abbreviations:
- AP,
- action potential;
- TTX,
- tetrodotoxin.
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Freely available online through the PNAS open access option.
- © 2007 by The National Academy of Sciences of the USA
