Hodgkin and Huxley established that sodium currents in the squid giant
axons activate after a delay, which is explained by the model of a
channel with three identical independent gates that all have to open
before the channel can pass current (the HH model). It is assumed that
this model can adequately describe the sodium current activation time
course in all mammalian central neurons, although there is no
experimental evidence to support such a conjecture. We performed high
temporal resolution studies of sodium currents gating in three types
of central neurons. ... These results can be explained by a model with
two closed states and one open state. ... This
model captures all major properties of the sodium current
activation. In addition, the proposed model reproduces the observed
action potential shape more accurately than the traditional HH model.
See paper for more and details.
Baranauskas G, Martina M (2006) Sodium currents activate without a Hodgkin-and-Huxley-type delay in central mammalian neurons. J Neurosci 26:671-84 [PubMed]