These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Threshold channels--a novel type of sodium channel in squid giant axon.
    Author: Gilly WF, Armstrong CM.
    Journal: Nature; ; 309(5967):448-50. PubMed ID: 6328313.
    Abstract:
    Sodium channels in nerve and muscle cells are functionally similar across wide phylogenetic boundaries and are usually thought to represent a single, homogeneous population that initiates the action potential at threshold and unerringly transmits it along the surface membrane. In marked contrast, many cell types are known to have several distinct potassium permeability systems. Distinguishable populations of Na channels have been reported in a few cell types, however, including denervated skeletal muscle, embryonic cardiac muscle, Purkinje cell somata and non-myelinated axons at low temperature. We report here that in squid giant axon, in standard experimental conditions, there are two functionally distinct populations of Na channels. The newly discovered population accounts for only a few per cent of the total Na permeability. The channels are selectively activated by small depolarizations and have very slow closing kinetics. Because these channels activate at voltages near the resting potential and tend to stay open for long times, they must dominate behaviour of the axon membrane in the threshold region for action potential initiation.
    [Abstract] [Full Text] [Related] [New Search]