Voltage Dependent Conductances: Gating Currents and Single Channel Recordings
Since Hodgkin and Huxley published their famous series in 1952, we know that the generation and propagation of the nerve impulse, or action potential, is the result of transient permeability changes of the axon membrane to sodium and potassium. These authors studied the membrane currents of the squid axon as a function of membrane voltage using the “voltage clamp” technique. They found that the membrane permeability is voltage and time dependent and is the result of at least two different conduction systems for sodium and potassium (see Fig. 1). In this classical work, Hodgkin and Huxley introduced the concept of voltage dependent ionic conductances and they even separated the process of conduction from the process of opening and closing of the permeability pathway. Today the permeability pathway is called ionic channel of which a large number of different types have been identified and the primary structure has been determined for several of them (e.g. Noda et al., 1984).
KeywordsSodium Channel Ionic Current Single Channel Voltage Dependence Test Pulse
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- Bezanilla, F., 1985, Gating of Sodium and Potassium Channels. J. Membrane Biol. 88, 97–111.Google Scholar
- Colquhoun, D., 1971, “Lectures on Biostatistics”. Clarendon Press, Oxford.Google Scholar
- Hodgkin, A. L. and Huxley, A. F., 1952, A quantitative description of Membrane current and its application to conduction and excitation in nerve. J. Physiol (Loud). 117, 500–544.Google Scholar
- Llano, I, C. K. Webb and F. Bezanilla, 1988, Potassium Conductance of the squid giant axon: single channel studies. J. Gen. Physiol. 92, 179–196.Google Scholar
- Noda, M., Shimizu, S., Tanabe, T., Takai, T., Kayano, T., Ikeda, T., Takahashi, H., Nakayama, H., Kanaoka, Y., Minamino, M., Kangawa, K., Matsuo, H.,Raftery, M. A., Hirose, T., Inayama, S., Hayashida, H., Miyata, T. and Numa, S., 1984, Primary structure of the Electrophorus electricus sodium channel deduced from cDNA sequence. Nature 312, 12 1127.Google Scholar
- Sackmann, B. and E. Neher., 1983, “Single-Channel Recording”. Plenum Press, New York.Google Scholar
- Stuhmer, W., F. Conti, H. Suzuki and X. Wang, M. Noda, N. Yahagi, H. Kubo, and S. Numa., 1989, Structural parts involved in activation and inactivation of the sodium channel. Nature 339, 597–603.Google Scholar