Neuronal Signaling. A Simple Thermodynamic Process Involving Complex Membrane Proteins

  • Franco Conti


Since the classical work of Hodgkin and Huxley1 the complex phenomenology of the transmission of electrical signals along nerve fibers is fully understood in terms of voltage and time dependence of the nerve membrane conductance. Also included in the Hodgkin-Huxley description of nerve excitation was the notion that the time delays characterizing the changes in membrane permeability must arise from simple voltage-dependent reactions involving specific molecular structures within the membrane itself. What could not be foreseen in 1952 was the fact that these structures, nowadays named ion channels, were bound to become one of the most important unifying concepts of membrane biophysics. It is now known that most functions of biological membranes are based on the performance of such specialized proteins, embedded in a common lipid bilayer matrix and characterized by their capability of assuming different conformations with probabilities which are determined, and thereby modulated, by the chemical and physical properties of their environment. Thus, both propagating action potentials (purely electrically driven) and synaptic signals (mediated by chemical agonists) are based on the same type of molecular event involving the opening of an aqueous pore within a membrane-spanning protein. With the advent of the patch-clamp technique pioneered by Neher and Sakmann2 the unitary electrical events produced by several kinds of ionic channels can be directly observed on the screen of an oscilloscope.3


Sodium Channel Channel Protein Sodium Current Neuronal Signaling Charge Redistribution 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    A.L. Hodgkin and A.F. Huxley, A quantitative description of membrane current and its application to conduction and excitation in nerve, J. Physiol. (Lond.), 117, 500 (1952).Google Scholar
  2. 2.
    E. Neher and B. Sakmann, Single-channel currents recorded from membrane of denervated frog muscle fibres, Nature, 260, 779 (1976).CrossRefGoogle Scholar
  3. 3.
    B. Sakmann and E. Neher, eds., Single channel recording, Plenum Press, New York (1983).Google Scholar
  4. 4.
    B. Hille, Ionic channels of excitable membranes, Sinauer Assoc. Inc., Suderland, Mass. (1984).Google Scholar
  5. 5.
    M. Noda, H. Takahashi, T. Tanabe, M. Toyosato, S. Kikyotani, Y. Furautani, T. Hirose, H. Takashima, W. Inazama, T. Miyata and S. Numa, Structural homology of Torpedo californica acetylcholine receptor subunits, Nature (Lond.), 302a, 528 (1983).CrossRefGoogle Scholar
  6. 6.
    M. Noda, S. Shimizu, T. Tanabe, T. Takai, T. Kayano, T. Ikeda, H. Takahashi, H. Nakayama, Y. Kanaoka, N. Minamino, K. Kangava, H. Matsuo, M.A. Raftery, T. Hirose, S. Inayma, H. Hayashida, T. Miyata and S. Numa, Primary structure of Electrophorus electricus sodium channel deduced from cDNA sequence, Nature (Lond.), 312, 121 (1984).CrossRefGoogle Scholar
  7. 7.
    B. Sakmann, C. Methfessel, M. Mishina, T. Takahashi, T. Takai, M. Kurasaki, K. Fukada and S. Numa, Role of acetylcholine receptor subunits in gating of the channel, Nature (Lond.), 318, 538 (1985).CrossRefGoogle Scholar
  8. 8.
    W. Stühmer, The effect of high extracellular potassium on the kinetics of potassium conductance of the squid axon membrane, Ph.D. Thesis, Technische Universität München, München, RFG (1980).Google Scholar
  9. 9.
    R.P. Swenson and C.M. Armstrong, K+ channels close more slowly in the presence of external K+ and Rb+, Nature (Lond.), 291, 427 (1981).CrossRefGoogle Scholar
  10. 10.
    J.M. Ritchie and R.B. Rogart, The binding of saxitoxin and tetrodotoxin to excitable tissue, Rev. Physiol. Biochem. Pharmacol., 79, 1 (1977).PubMedCrossRefGoogle Scholar
  11. 11.
    F. Conti, Noise analysis and single channel recordings, Current Topics in Membrane and Transport, 22, 371 (1984).CrossRefGoogle Scholar
  12. 12.
    W. Aimers, Gating currents and charge movements in excitable membranes, Rev. Physiol. Biochem. Pharmacol., 82, 96 (1978).CrossRefGoogle Scholar
  13. 13.
    F.J. Sigworth, Open channel noise I. Noise in acetylcholine receptor currents suggests conformational fluctuations, Biophys. J., 47, 709 (1985).PubMedCrossRefGoogle Scholar
  14. 14.
    F. Conti and E. Wanke, Channel noise in nerve membranes and lipid bilayers, Q. Rev. Biophys., 8, 451 (1975).PubMedCrossRefGoogle Scholar
  15. 15.
    F. Conti, The relationship between electrophysiological data and thermodynamics of ion channel conformations, Neurol. Neurobiol., 20, 25 (1986).Google Scholar
  16. 16.
    T.L. Hill, An introduction to statistical thermodynamics, Addison-Wesley, Reading, Mass (1960).Google Scholar
  17. 17.
    A.L. Hodgkin and A.F. Huxley, The dual effect of membrane potential on sodium conductance in the giant axon of Loligo, J. Physiol. (Lond.), 116, 497 (1952).Google Scholar
  18. 18.
    C.M. Armstrong and F. Bezanilla, Inactivation of the sodium channel. II. Gating current experiments, J. Gen. Physiol., 70, 567 (1977).PubMedCrossRefGoogle Scholar
  19. 19.
    J.E. Kimura and H. Meves, The effect of temperature on the asymmetrical charge movement in squid giant axons, J. Physiol. (Long.), 289, 479 (1979).Google Scholar
  20. 20.
    C.M. Armstrong and W.F. Gilly, Fast and slow steps in the activation of Na channels, J. Gen. Physiol., 74, 691 (1979).PubMedCrossRefGoogle Scholar
  21. 21.
    R.D. Keynes, Voltage-gated ion channels in the nerve membrane, Proc. R. Soc. Lond., 220, 1 (1983).PubMedCrossRefGoogle Scholar
  22. 22.
    F. Conti, I. Inoue, F. Kukita and W. Stühmer, Pressure dependence of sodium gating currents in the squid giant axon, Eur. Biophys. J., 11, 137 (1984).PubMedCrossRefGoogle Scholar
  23. 23.
    K.T. Wann and A.G. Macdonald, The effects of pressure on excitable cells, Comp. Biochem. Physiol., 66A, 1 (1980).CrossRefGoogle Scholar
  24. 24.
    F. Conti, R. Fioravanti, J.R. Segal and W. Stühmer, Pressure dependence of the socium current of squid giant axon, J. Membr. Biol., 69, 23 (1982).PubMedCrossRefGoogle Scholar
  25. 25.
    F. Conti, R. Fioravanti, J.R. Segal and W. Stühmer, Pressure dependence of the potassium currents of squid giant axon, J. Membr. Biol., 69, 35 (1982).PubMedCrossRefGoogle Scholar
  26. 26.
    R. Benz, F. Conti and R. Fioravanti, Extrinsic charge movement in the squid axon membrane: effect of pressure and temperature, Eur. Biophys. J., 11, 51 (1984).PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1986

Authors and Affiliations

  • Franco Conti
    • 1
  1. 1.Istituto di Cibernetica e BiofisicaCNRGenovaItaly

Personalised recommendations