Energy-efficient action potentials in hippocampal mossy fibers.
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.
Alle
Henrik
H
Independent Hertie Research Group, Max-Planck-Institute for Brain Research, 60528 Frankfurt, Germany. henrik.alle@charite.de
Roth
Arnd
A
Geiger
Jörg R P
JR
D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000502:physiology; D004734:Energy Metabolism; D019599:Mossy Fibers, Hippocampal / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism; D017729:Presynaptic Terminals / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D009435:Synaptic Transmission
D015221:Potassium Channels; D015222:Sodium Channels; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium