Kinetics and steady‐state properties of the charged system controlling sodium conductance in the squid giant axon

@article{Keynes1974KineticsAS,
  title={Kinetics and steady‐state properties of the charged system controlling sodium conductance in the squid giant axon},
  author={Richard Darwin Keynes and Eduardo Rojas},
  journal={The Journal of Physiology},
  year={1974},
  volume={239}
}
1. Asymmetries in the early time course of the displacement current passing across the membrane after application of equal voltage‐clamp pulses in the two directions have been investigated in the squid giant axon. Before making the measurements, Na current was blocked by removal of external Na and treatment with tetrodotoxin. Potassium current was usually blocked by perfusion with CsF, but some experiments were done with intact axons. A signal averaging technique was used to eliminate the… 
Kinetics of activation of the sodium conductance in the squid giant axon.
TLDR
Comparisons of the voltage dependence of tau m with that of the time constant tAU 1 of the fast relaxation of the asymmetry current measured in the same axon showed that tau 1 was smaller than taum except at positive potentials, was less steeply voltage‐dependent, and reached its maximum at a more positive potential.
The temporal and steady‐state relationships between activation of the sodium conductance and movement of the gating particles in the squid giant axon.
TLDR
In the perfused axons the state of the membrane was better described by the constant field equation than by gNa, and the gating current time constant tau(V) was found to lie on a very similar bell‐shaped curve.
On the relation between displacement currents and activation of the sodium conductance in the squid giant axon.
  • E. Rojas, R. Keynes
  • Biology, Physics
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 1975
TLDR
It is proposed that these displacement currents arise from a redistribution of the charges involved in the sodium gating system, consistent with a Boltzmann distribution of charges between two states characterized by different energy levels.
Potassium and sodium ion current noise in the membrane of the squid giant axon.
TLDR
The spectral density of current noise power from 20 mm segments of giant axons of the squid Loligo vulgaris has been measured and the measured noise is larger by several orders of magnitude than the theoretical thermal noise.
Asymmetry currents in intracellularly perfused squid giant axons.
  • H. Meves
  • Biology
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 1975
TLDR
Asymmetry currents were recorded from intracellularly perfused squid axons subjected to exactly equal positive and negative voltage clamp pulses at a temperature close to 0 degrees C and experiments showed that the voltage dependence of the asymmetrical charge movement is different from the voltage dependent of the m system.
The effect of holding potential on the asymmetry currents in squid giant axons
  • H. Meves
  • Biology
    The Journal of physiology
  • 1974
1. Asymmetry currents were recorded from intracellularly perfused squid axons subjected to an equal number of exactly equal positive and negative voltage clamp pulses. The asymmetry currents
Fractionation of the asymmetry current in the squid giant axon into inactivating and non-inactivating components
The operation of the voltage-sensitive sodium gating system in the nerve membrane involves conformational changes that are accompanied by small asymmetrical displacement currents. The asymmetry
The early phase of sodium channel gating current in the squid giant axon
TLDR
The property of kinetic independence allows subtraction of this component from the total displacement current to reveal a rising phase in the early time course of the remaining current, which will have to be taken into account when modelling the voltage-dependent sodium channel.
Gating currents in the node of Ranvier: voltage and time dependence.
TLDR
The results suggest that the presence of ten times more sodium channels in the node of Ranvier than in the squid giant axon with similar sodium conductance per channel is suggested.
Kinetic analysis of the sodium gating current in the squid giant axon
A critical study has been made of the characteristics of the kinetic components of the sodium gating current in the squid giant axon, of which not less than five can be resolved. In addition to the
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