Properties of the voltage sensor for the opening and closing of the sodium channels in the squid giant axon

1993 ◽  
Vol 253 (1336) ◽  
pp. 61-68 ◽  
Keyword(s):  
Sodium Channels ◽  
Giant Axon ◽  
Squid Giant Axon ◽  
Voltage Sensor ◽  
Opening And Closing

scholarly journals Analysis of sodium current fluctuations in the cut-open squid giant axon.

1984 ◽  
Vol 83 (2) ◽  
pp. 133-142 ◽  
Author(s):  
I Llano ◽  
F Bezanilla
Keyword(s):  
Sodium Channel ◽  
Sodium Channels ◽  
Sodium Current ◽  
Giant Axon ◽  
Squid Giant Axon ◽  
Statistical Techniques ◽  
Current Fluctuations ◽  
Small Populations ◽  
Squid Axon ◽  
Single Sodium Channel

Patch pipettes were used to record the current arising from small populations of sodium channels in voltage-clamped cut-open squid axons. The current fluctuations associated with the time-variant sodium conductance were analyzed with nonstationary statistical techniques in order to obtain an estimate for the conductance of a single sodium channel. The results presented support the notion that the open sodium channel in the squid axon has only one value of conductance, 3.5 pS.

Interaction of DDT with sodium channels in squid giant axon membranes

Neuroscience ◽  
1981 ◽  
Vol 6 (11) ◽  
pp. 2253-2258 ◽  
Author(s):  
A.E. Lund ◽  
T. Narahashi
Keyword(s):  
Sodium Channels ◽  
Giant Axon ◽  
Squid Giant Axon ◽  
Axon Membranes

The rate of action of tetrodotoxin on sodium conductance in the squid giant axon

1975 ◽  
Vol 270 (908) ◽  
pp. 365-375 ◽  
Keyword(s):  
Schwann Cell ◽  
Sodium Channels ◽  
Binding Sites ◽  
Node Of Ranvier ◽  
Giant Axon ◽  
Squid Giant Axon ◽  
Free Diffusion ◽  
Sodium Conductance ◽  
In Series ◽  
Order Of Magnitude

When tetrodotoxin is applied to or washed away from the squid giant axon, the rates at which the sodium conductance is blocked and unblocked are an order of magnitude smaller than those reported for the isolated node of Ranvier. This slowing is to be expected if in squid the tetrodotoxin binding sites act as a saturable sink in series with the barrier to free diffusion imposed by the presence of the Schwann cell. A comparison has been made between the rates observed experimentally and those calculated for a computer model of the system, in order to estimate the apparent density in the membrane of both specific and non-specific tetrodotoxin binding sites. The figure thus obtained for the number of sodium channels in the squid giant axon, several hundred per square micrometre, agrees well with those derived from other lines of argument.

The relationship between the inactivating fraction of the asymmetry current and gating of the sodium channel in the squid giant axon

1982 ◽  
Vol 215 (1200) ◽  
pp. 391-404 ◽  
Keyword(s):  
Conformational Changes ◽  
Voltage Dependence ◽  
Ionic Currents ◽  
Giant Axon ◽  
Quantitative Comparison ◽  
Squid Giant Axon ◽  
Relative Timing ◽  
Sodium System ◽  
Opening And Closing ◽  
The Relationship

A quantitative comparison between the voltage dependence of the inactivating component of the asymmetrical charge transfer in the squid giant axon and that of the sodium conductance indicates that activation of the sodium system involves either three subunits operating in parallel or a three-step series mechanism. This is confirmed by an examination of the relative timing of the flow of asymmetry and ionic currents during the opening and closing of the sodium channels. In agreement with previous suggestions, inactivation is coupled sequentially to activation. The evidence appears to argue against a trimeric system with three wholly independent subunits and favours a monomeric system that undergoes a complex sequence of conformational changes.

scholarly journals The conductance and density of sodium channels in the cut-open squid giant axon.

1986 ◽  
Vol 377 (1) ◽  
pp. 463-486 ◽  
Author(s):  
J M Bekkers ◽  
N G Greeff ◽  
R D Keynes
Keyword(s):  
Sodium Channels ◽  
Giant Axon ◽  
Squid Giant Axon
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