Voltage-clamped steps in the electric potential difference (PD) across the membrane in cells of the green alga,Chara inflata, cause voltage- and time-dependent current flows, interpreted to arise from opening and closing of various types of ion channel in the membrane. With cells in the light, these channels are normally closed, and the resting PD is probably determined by the operation of an H+ efflux pump. Positive steps in PD from the resting level often caused the opening of K+ channels with sigmoid kinetics. The channels began to show opening when the PD≃−120 mV for an external concentration of K+ of 1.0mm. Return of the PD to the resting level caused closing of the channels with complex kinetics. Various treatments of the cell could cause these K+ channels to open, and remain open continuously, with the PD then lying closer to the Nernst PD for K+. The K+ channels have been identified by the blocking effects of TEA+. Another group of channels, probably Cl− and Ca2+ associated with the action potential open when the PD is stepped to values less negative than ≃−50 mV. Negative steps from the resting PD cause the slow opening, with a time course of seconds, of yet another type of channel, probably Cl−.
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Armstrong, C.M. 1975. Ionic pores, gates and gating currents.Q. Rev. Biophys. 7:179–210
Beilby, M.J., Beilby, B.N. 1983. Potential dependence of the admittance ofChara plasmalemma.J. Membrane Biol. 74:229–245
Beilby, M.J., Coster, H.G.L. 1979. The action potential inChara corallina. II. Two activation-inactivation transients in voltage clamps of the plasmalemma.Aust. J. Plant Physiol. 6:323–335
Coster, H.G.L. 1969. The role of pH in the punch-through effect in the electrical characteristics ofChara australis.Aust. J. Biol. Sci. 22:365–374
Findlay, G.P. 1982. Electrogenic and diffusive components of the membrane ofHydrodictyon africanum.J. Membrane Biol. 68:179–189
Findlay, G.P., Coleman, H.A. 1983. Potassium channels in the membrane ofHydrodictyon africanum.J. Membrane Biol. 75:241–251
Findlay, G.P., Hope, A.B. 1964. Ionic relation of cells ofChara australis. VII. The separate electrical characteristics of the plasmalemma and tonoplast.Aust. J. Biol. Sci. 17:62–77
Findlay, G.P., Hope, A.B. 1976. Electrical properties of plant cells: Methods and findings.In: Encyclopedia of Plant Physiology. New Series, Vol. 2, Part A. Transport in Plants II. U. Lüttge and M.G. Pitman, editors. pp. 53–92. Springer. Berlin-Heidelberg-New York
Findlay, G.P., Tyerman, S.D. 1984. Voltage-dependent inward current in the membrane ofChara inflata.In: Membrane Permeability: Experiments and Models. A. Bretag, editor. pp. 39–42. Techsearch, Adelaide
Hodgkin, A.L., Huxley, A.F. 1952. Currents carried by sodium and potassium ions through the membrane of the giant axon ofLoligo.J. Physiol. (London) 116:449–472
Hope, A.B. 1965. Ionic relation of cells ofChara australis. X. Effects of bicarbonate ions on electrical properties.Aust. J. Biol. Sci. 18:789–801
Hope, A.B., Findlay, G.P. 1964. The action potential inChara.Plant Cell Physiol. 5:377–379
Keifer, D.W., Lucas, W.J. 1982. Potassium channels inChara corallina.Plant Physiol. 69:781–788
Kishimoto, U. 1966. Hyperpolarising response inNitella internodes.Plant Cell Physiol. 7:429–439
Latorre, R., Coronado, R., Vergara, C. 1984. K+ channels gated by voltage and ions.Annu. Rev. Physiol. 46:485–495
Ohkawa, T., Kishimoto, U. 1977. Breakdown phenomena in theChara membrane.Plant Cell Physiol 18:67–80
Smith, P.T., Walker, N.A. 1981. Studies on the perfused plasmalemma ofChara corallina: I. Current-voltage curves: ATP and potassium dependence.J. Membrane Biol. 60223–236
Tazawa, M., Shimmen, T. 1980. Action potential in characeae: Some characteristics revealed by internal perfusion studies.In: Plant Membrane Transport: Current Conceptual Issues. R.M. Spanswick, W.J. Lucas and J. Dainty, editors. pp. 349–362. Elsevier-North Holland Biomedical, Amsterdam
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Coleman, H.A., Findlay, G.P. Ion channels in the membrane ofChara inflata . J. Membrain Biol. 83, 109–118 (1985). https://doi.org/10.1007/BF01868743
- K+ channels
- ion channels
- Chara inflata
- TEA+ effects