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Science 11 September 2009:
Vol. 325. no. 5946, pp. 1405 - 1408
DOI: 10.1126/science.1174331
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Reports

Energy-Efficient Action Potentials in Hippocampal Mossy Fibers

Henrik Alle,1,*,{dagger} Arnd Roth,2 Jörg R. P. Geiger1,*

Action potentials in nonmyelinated axons are considered to contribute substantially to activity-dependent brain metabolism. Here we show that fast Na+ current decay and delayed K+ current onset during action potentials in nonmyelinated mossy fibers of the rat hippocampus minimize the overlap of their respective ion fluxes. This results in total Na+ influx and associated energy demand per action potential of only 1.3 times the theoretical minimum, in contrast to the factor of 4 used in previous energy budget calculations for neural activity. Analysis of ionic conductance parameters revealed that the properties of Na+ and K+ channels are matched to make axonal action potentials energy-efficient, minimizing their contribution to activity-dependent metabolism.

1 Independent Hertie Research Group, Max-Planck-Institute for Brain Research, 60528 Frankfurt, Germany.
2 Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.

* Present address: Institute of Neurophysiology, Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.

{dagger} To whom correspondence should be addressed. E-mail: henrik.alle{at}charite.de

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