The mobility and diffusion coefficient of potassium in giant axons from Sepia

  title={The mobility and diffusion coefficient of potassium in giant axons from Sepia},
  author={Alan Lloyd Hodgkin and Richard Darwin Keynes},
  journal={The Journal of Physiology},
The object of the experiments described here is to measure the mobility and diffusion coefficient of the potassium ions inside the giant axons of Sepia officinalis. The principle of the method is to make a short length of axoplasm radioactive by allowing internal potassium to exchange with externally applied 42K in a restricted region. If a fibre which has been treated in this way is washed with sea water and placed in oil, most of the 42K remains in the axoplasm since the extracellular space… 
Diffusion of ions in myelinated nerve fibers.
Electrophoretic migration of intracellular cations in the toad sartorius muscle.
  • K. Noda
  • Biology
    The Kurume medical journal
  • 1965
The results thus obtained suggest that the cell contains a considerable quantity of freely diffusible ions, and may also offer a suggestion as to the concept that the driving force on the potassium ion in an outward direction is the potential energy.
Diffusion of sodium in axoplasm of myelinated nerve fibre. Potential clamp analysis.
  • P. Århem
  • Biology
    Acta physiologica Scandinavica
  • 1976
The diffusion of sodium and lithium in the axoplasm of myelinated fibres of Xenopus laevis was investigated and it was found that the experimental results were satisfactorily predicted by this model axon.
The permeability of the squid giant axon to radioactive potassium and chloride ions
The purpose of this paper is to give a brief account of the preliminary influx determinations, and of a few experiments on the K efflux from axons into which 42K had been injected.
  • A. Huxley
  • Biology
    Annals of the New York Academy of Sciences
  • 1959
There are several different ways in which the electric activity of a nerve fiber depends on movements of inorganic ions, including in the maintenance of the resting potential, which Bernstein (1902) suggested was a concentration potential.
Ionophoresis along frog muscle
Hodgkin & Keynes (1950, 1953), working with isolated nerve fibres from Sepia, were able to show that the diffusion constant and the mobility of the radioactive K ions they had introduced into the nerve were little, if at all, less than those of K ions in free solution.
Movement of radioactive potassium and membrane current in a giant axon
The experiments described here were designed to test the point that the prolonged outward current associated with depolarization is carried by potassium ions and the affirmative answer which they provide has already been mentioned in earlier papers.
The measurement of sodium and potassium activities in the squid axon by means of cation‐selective glass micro‐electrodes
The aim of the experiments in this paper was to measure sodium and potassium activities inside and outside the isolated giant axon of the squid in order to relate the cation equilibrium potentials to the resting and action potential of the cell membrane.
Potassium movements in washed erythrocytes
  • T. I. Shaw
  • Biology, Environmental Science
    The Journal of physiology
  • 1955
Results have been extended to cover a wider range of potassium concentrations using horse, ox and sheep red cells as experimental material and the relationship between potassium influx and efflux studied.
Transport of Na+ inside the giant axon of squid
  • D. Chang
  • Biology
    Cell Biochemistry and Biophysics
  • 2007
Results of this study indicate that the intracellular transport of Na+ and the fast axonal transport are two independent processes.


The electrical constants of a crustacean nerve fibre
  • A. Hodgkin, W. Rushton
  • Biology
    Proceedings of the Royal Society of London. Series B - Biological Sciences
  • 1946
The behaviour of lobster axons agreed with theoretical predictions in the following respects: (a) the steady extrapolar potential declined exponentially with distance; (b) the voltage gradient midway between two distant electrodes was uniform; (c) the rise and fall of the extrapolars at different distances conformed to the correct theoretical curves.
  • K. Cole
  • Biology
    The Journal of general physiology
  • 1941
A formal analogy is found between the calculated membrane potential and the excitability defined by the two factor formulations of excitation and several excitation phenomena may be explained semi-quantitatively by further assuming the excitable proportional to the membrane potential.
The sodium and potassium content of cephalopod nerve fibres
The ionic movements during nervous activity
  • R. Keynes
  • Psychology
    The Journal of physiology
  • 1951
Studies on permeability in relation to nerve function, axonal conduction and synaptic transmission.
Electrical characteristics of sepia axons
  • S. Weidmann
  • Chemistry, Medicine
    The Journal of physiology
  • 1951