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Energy-Efficient Action Potentials in Hippocampal Mossy Fibers

Science  11 Sep 2009:
Vol. 325, Issue 5946, pp. 1405-1408
DOI: 10.1126/science.1174331

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Abstract

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.

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

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