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Do neurons have a reserve of sodium channels for the generation of action potentials? A study on acutely isolated CA1 neurons from the guinea‐pig hippocampus
Author(s) -
Madeja Michael
Publication year - 2000
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2000.00871.x
Subject(s) - sodium channel , tetrodotoxin , sodium , sodium channel blocker , neuron , chemistry , neuroscience , membrane potential , biophysics , ion channel , electrophysiology , hippocampal formation , resting potential , biology , receptor , biochemistry , organic chemistry
The density of voltage‐gated sodium channels is high in several regions of the neuronal membrane. It is unclear if this density of channels represents a reserve for the neuron, or if it fulfils a special role in action potential firing. This problem was addressed by studying sodium currents and action potentials in acutely isolated hippocampal CA1 neurons whose number of active sodium channels was acutely changed by applying the sodium channel blocker tetrodotoxin (TTX) at different concentrations. The results show that more than a third of the sodium channels can fail without affecting the single action potential. Thus, the neurons have a remarkable surplus of sodium channels. The surplus, however, is necessary for repetitive action potential firing, as every decrease in the fraction of sodium channels reduces the maximal frequency of action potentials that can be generated by the neuron.