Advertisement

The Journal of Membrane Biology

, Volume 109, Issue 1, pp 9–19 | Cite as

Current-voltage relationships of a sodium-sensitive potassium channel in the tonoplast ofChara corallina

  • Adam Bertl
Articles

Summary

The membrane of mechanically prepared vesicles ofChara corallina has been investigated by patch-clamp techniques. This membrane consists of tonoplast as demonstrated by the measurement of ATP-driven currents directed into the vesicles as well as by the ATP-dependent accumulation of neutral red. Addition of 1mm ATP to the bath medium induced a membrane current of about 3.2 mA·m−2 creating a voltage across the tonoplast of about −7 mV (cytoplasmic side negative). On excised tonoplast patches, currents through single K+-selective channels have been investigated under various ionic conditions. The open-channel currents saturate at large voltage displacements from the equilibrium voltage for K+ with limiting currents of about +15 and −30 pA, respectively, as measured in symmetric 250mm KCl solutions. The channel is virtually impermeable to Na+ and Cl. However, addition of Na+ decreases the K+ currents. TheI–V relationships of the open channel as measured at various K+ concentrations with or without Na+ added are described by a 6-state model, the 12 parameters of which are determined to fit the experimental data.

Key Words

Chara corallina tonoplast K+ channel Na+ effect cyclic model 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Beilby, M. J. 1985. Potassium channels atChara plasmalemma.J. Exp. Bot. 36:228–239Google Scholar
  2. Bertl, A., Gradmann, D. 1987. Current-voltage relationships of potassium channels in the plasmalemma ofAcetabularia.J. Membrane Biol. 99:41–49Google Scholar
  3. Bertl, A., Klieber, H.G., Gradmann, D. 1988. Slow kinetics of a potassium channel inAcetabularia.J. Membrane Biol. 102:141–152Google Scholar
  4. Coster, H.G.L., Smith, J.R. 1977. Low-frequency impedance ofChara corallina: Simultaneous measurements of the separate plasmalemma and tonoplast capacitance and conductance.Aust. J. Plant Physiol. 4:667–674Google Scholar
  5. Coyaud, L., Kurkdjian, A., Kado, R., Hedrich, R. 1987. Ion channels and ATP-driven pumps involved in ion transport across the tonoplast of sugar beet vacuoles.Biochim. Biophys. Acta 902:263–268Google Scholar
  6. Findlay, G.P., Hope, A.B. 1964. Ionic relations of cells ofChara australis VII. The separate electrical characteristics of the plasmalemma and tonoplast.Aust. J. Biol. Sci. 17:62–77Google Scholar
  7. Gradmann, D., Klieber, H.G., Hansen, U.P. 1987. Reaction kinetic parameters for ion transport from steady state currentvoltage curves.Biophys. J. 51:569–585Google Scholar
  8. Hamill, O.P., Marty, A., Neher, E., Sakmann, B., Sigworth, F.J. 1981. Improved patch-clamp techniques for high resolution current recording from cells and cell-free membrane patches.Pfluegers Arch. 391:85–100Google Scholar
  9. Hansen, U.P., Gradmann, D., Sanders, D., Slayman, C.L. 1981. Interpretation of current-voltage relationships for “active” ion transport systems: I. Steady-state reaction-kinetic analysis of Class-I mechanisms.J. Membrane Biol. 63:165–190Google Scholar
  10. Hedrich, R., Barbier-Brygoo, H., Felle, H., Flügge, U.I., Lüttge, U., Maathuis, F.J.M., Marx, S., Prins, H.B.A., Raschke, K., Schnabl, H., Schroeder, J.I., Struve, I., Taiz, L., Ziegler, P. 1988. General mechanisms for solute transport across the tonoplast of plant vacuoles: A patch-clamp survey of ion channels and proton pumps.Botan. Acta 1:7–13Google Scholar
  11. Hedrich, R., Flügge, U.I., Fernandez, J.M. 1986. Patch-clamp studies of ion transport in isolated plant vacuoles.FEBS Lett. 204:228–232Google Scholar
  12. Hedrich, R., Neher, E. 1987. Regulation of voltage-dependent ion channels in plant vacuoles by cytoplasmic calcium.Nature (London) 329:834–836Google Scholar
  13. Homble, F., Ferrier, J.M., Dainty, J. 1987. Voltage-dependent K+-channel in protoplasmic droplets ofChara corallina. A single channel patch clamp study.Plant Physiol. 83:53–57Google Scholar
  14. Hope, A.B., Walker, N.A. 1975. The Physiology of Giant Algal Cells. Cambridge University Press, LondonGoogle Scholar
  15. Läuger, P. 1976. Diffusion-limited ion flow through pores.Biochim. Biophys. Acta 455:493–509Google Scholar
  16. Läuger, P., Stark, G. 1970. Kinetics of carrier-mediated transport across lipid bilayer membranes.Biochim. Biophys. Acta 211:458–466Google Scholar
  17. Laver, D.R., Walker, N.A. 1987. Steady state voltage-dependent gating and conduction kinetics of single K+ channels in the membrane of cytoplasmic drops ofChara australis.J. Membrane Biol. 100:31–42Google Scholar
  18. Lühring, H. 1986. Recording of single K+ channels in the membrane of cytoplasmic drop ofChara australis.Protoplasma 133:19–28Google Scholar
  19. Moriyasu, Y., Shimmen, T., Tazawa, M. 1984. Electrical characteristics of the vacuolar membrane ofChara in relation to pHv regulation.Cell Struct. Funct. 9:235–246Google Scholar
  20. Reeves, M., Shimmen, T., Tazawa, M. 1985. Ionic activity gradients across the surface membrane of cytoplasmic droplets prepared fromChara australis.Plant Cell Physiol. 26:1185–1193Google Scholar
  21. Sakano, K., Tazawa, M. 1986. Tonoplast origin of the envelope membrane of cytoplasmic droplets prepared fromChara internodal cells.Protoplasma 113:247–249Google Scholar
  22. Sakmann, B., Neher, E. 1983. Single-Channel Recording. Plenum, New YorkGoogle Scholar
  23. Shimmen, T., Tazawa, M. 1983. Control of cytoplasmic streaming by ATP, Mg2+ and cytochalasin B in permeabilizedCharaceae cell.Protoplasma 115:18–24Google Scholar
  24. Svintitskikh, V.A., Andrionov, V.K., Bulychev, A.A. 1985. Photo-induced H+ transport between chloroplasts and the cytoplasm in a protoplasmic droplet ofCharaceae.J. Exp. Bot. 36:1414–1429Google Scholar
  25. Tazawa, M., Kikuyama, M., Shimmen, T. 1976. Electrical characteristics and cytoplasmic streaming ofCharaceae cells lacking tonoplast.Cell Struct. Funct. 1:167–176Google Scholar
  26. Tester, M., Beilby, M., Shimmen, T. 1987. Electrical characteristics of the tonoplast ofChara corallina: A study using permeabilised cells.Plant Cell Physiol. 28:1555–1568Google Scholar

Copyright information

© Springer-verlag New York Inc. 1989

Authors and Affiliations

  • Adam Bertl
    • 1
  1. 1.Pflanzenphysiologisches Institut und Botanischer Garten der Universität GöttingenGöttingenFederal Republic of Germany

Personalised recommendations