Phosphorylation-dependent differences in the activation properties of distal and proximal dendritic Na+ channels in rat CA1 hippocampal neurons

At distal dendritic locations, the threshold for action potential generation is higher and the amplitude of back-propagating spikes is decreased. To study whether these characteristics depend upon Na + channels, their voltage-dependent properties at proximal and distal dendritic locations were compa...

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Bibliographic Details
Published in:The Journal of physiology 2002-06, Vol.541 (3), p.665-672
Main Authors: Gasparini, Sonia, Magee, Jeffrey C.
Format: Article
Language:English
Subjects:
Algorithms
Animals
Axons - physiology
Dendrites - physiology
Electrophysiology
Enzyme Inhibitors - pharmacology
Hippocampus - cytology
Hippocampus - physiology
In Vitro Techniques
Membrane Potentials - physiology
Neurons - physiology
Patch-Clamp Techniques
Phosphorylation
Protein Kinase Inhibitors
Rapid Report
Rats
Rats, Sprague-Dawley
Sodium Channels - physiology
Staurosporine - pharmacology
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Summary:At distal dendritic locations, the threshold for action potential generation is higher and the amplitude of back-propagating spikes is decreased. To study whether these characteristics depend upon Na + channels, their voltage-dependent properties at proximal and distal dendritic locations were compared in CA1 hippocampal neurons. Distal Na + channels activated at more hyperpolarized voltages than proximal (half-activation voltages were −20.4 ± 2.4 mV vs. −12.0 ± 1.7 mV for distal and proximal patches, respectively, n = 16, P < 0.01), while inactivation curves were not significantly different. The resting membrane potential of distal regions also appeared to be slightly but consistently more hyperpolarized than their proximal counterpart. Staurosporine, a non-selective protein kinase inhibitor, shifted the activation curves for both proximal and distal Na + channels to the left so that they overlapped and also caused the resting potentials to be comparable. Staurosporine affected neither the inactivation kinetics of Na + currents nor the reversal potential for Na + . These results suggest that the difference in the voltage dependence of activation of distal and proximal Na + channels can be attributed to a different phosphorylation state at the two locations.
ISSN:0022-3751
1469-7793
DOI:10.1113/jphysiol.2002.020503