, Volume 28, Issue 6, pp 193–201 | Cite as

Characterization of single K+ channels inHelix pomatia neurons

  • E. A. Lukyanetz
  • A. V. Sotkis


The measurements of unitary outward ion currents in unidentified neurons of the snailHelix pomatia with the patch-clamp technique in a cell-attached configuration showed the presence of several types of K+ channels. We investigated three types of K+ channels: with big (75 pS, BKC), medium (22 pS, MKC), and small (6.2 pS, SKC) unitary conductance. BKC and MKC were activated at a membrane potential of about −30 mV, whereas SKC were activated at more negative potentials, with opening probability of the latter channels significantly decreasing at potentials more positive than −30 mV. Pharmacological investigation showed that BKC and MKC channel activity disappeared after 8–10 min of cell patching with a pipette solution containing 60 mM Cs+, whereas MKC channels remained unaffected. BKC and MKC were proved to be more sensitive to TEA (20 mM), whereas SKC were selectively sensitive to 4-AP (10 mM). Cd2+ (100 µM) in the pipette solution decreased the unitary conductance of BKC channels by 55 % and that of MKC channels by about 31 %. In contrast, the unitary conductance of SKC channels was not changed by the above blocker. Bath application of 10 µM 5-HT showed that MKC were suppressed by 5-HT, whereas SKC and BKC were insensitive to this transmitter. It is supposed that BKC can be classified as big-conductance Ca2+-dependent K+ channels (KCa) or to 5-HT-sensitive K+ channels (S-type channels), while MKC correspond to intermediate-conductance KCa, and SKC channels comply well with the characteristics of A-type K+ current.


Membrane Potential Channel Activity Negative Potential Pipette Solution Bath Application 
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  1. 1.
    M. J. Christie, “Molecular and functional diversity of K+ channels,”Clin. Exp. Pharmacol. Physiol.,22, 944–951 (1995).Google Scholar
  2. 2.
    G. Edwards and A. H. Weston, “The role of potassium channels in excitable cells,”Diabetes Res. Clin. Pract.,28, S57–66 (1995).Google Scholar
  3. 3.
    E. Neher, “Two fast transient current components during voltage clamp on snail neurons,”J. Gen. Physiol.,58, 36–53 (1971).Google Scholar
  4. 4.
    S. H. Thompson, “Three pharmacologically distinct potassium channels in molluscan neurons,”J. Physio.,265, 465–488 (1977).Google Scholar
  5. 5.
    A. Hermann and K. Hartung, “Ca2+ activated K+ conductance in molluscan neurons,”Cell Calcium,4, 387–405 (1983).Google Scholar
  6. 6.
    A. N. Kachman, M. V. Samoilova, and V. A. Snetkov, “Single potassium channel of anomalous (inward) rectification in molluscan neurons,”Neirofiziologiya,21, No. 1, 31–38 (1989).Google Scholar
  7. 7.
    M. Klein and E. R. Kandel, “Presynaptic modulation of voltagedependent Ca2+ current, mechanism for behavioral sensitization inAplysia californica,”Proc. Natl. Acad. Sci. USA,75, 3512–3516 (1978).Google Scholar
  8. 8.
    D. Pollock and J. S. Camardo, “Regulation of single potassium channels by serotonin in the cell bodies of the tail mechanosensory neurons ofAplysia californica,”Brain Res.,410, 367–370 (1987).Google Scholar
  9. 9.
    M. J. Shuster and S. A. Siegelbaum, “Pharmacological characterization of the serotonin-sensitive potassium channel ofAplysia sensory neurons,”J. Gen. Physiol.,90, No. 4, 587–608 (1987).Google Scholar
  10. 10.
    A. Voltera and S. A. Siegelbaum, “Role of two different guanine nucleotide-binding proteins in the antagonistic modulation of the S-type K+ channel by cAMP and arachidonic acid metabolities inAplysia sensory neurons,”Proc. Natl. Acad. Sci. USA,85, 7810–7814 (1988).Google Scholar
  11. 11.
    P. G. Kostyuk and A. E. Martynyuk, “Potassium outward current dependent on extracellular calcium in snall neuronal membrane,”Neuroscience,24, 1081–1087 (1988).Google Scholar
  12. 12.
    A. H. Drummond, J. A. Benson, and I. B. Levitan, “Serotonininduced hyperpolarization of an identifiedAplysia neuron is mediated by cyclic AMP,”Proc. Natl. Acad. Sci. USA,77, 5013–5017 (1980).Google Scholar
  13. 13.
    P. Deterre, D. Paupardin-Tritsch, J. Bockaert, and H. M. Gerschenfeld, “Role of cyclic AMP in serotonin-evoked slow inward current in snail neurons,”Nature,290, 783–785 (1981).Google Scholar
  14. 14.
    J. S. Lemos, I. Novak-Hofer, and I. B. Levitan, “Phosphoproteins associated with the regulation of a specific potassium channel in the identifiedAplysia neuron R15,”J. Biol. Chem,260, No. 10, 3207–3214 (1985).Google Scholar
  15. 15.
    E. A. Luk'yanets (Lukyanetz) and P. G. Kostyuk, “Two distinct receptors operate the cAMP cascade to up-regulate L-type Ca channels,”Pflügers Arch.,432, 174–181 (1996).Google Scholar
  16. 16.
    O. P. Hamill, A. Marty, E. Neher, et al., “Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches,”Pflügers Arch.,391, 85–100 (1981).Google Scholar
  17. 17.
    M. Crest and M. Gola, “Large conductance Ca2+-activated K+ channels are involved in both spike shaping and firing regulation inHelix neurons,”J. Physiol.,465, 265–287 (1993).Google Scholar
  18. 18.
    B. Hille,Ionic Channels in Excitable Membranes, Sinauer Inc., Sunderland MA, USA (1984).Google Scholar
  19. 19.
    P. G. Kostyuk, A. I. Vislobokov, P. A. Doroshenko, et al., “The action of 3,5-diamino-2-thio-2,4-diazole on the electrically excitable membrane of molluscan nerve cells,”Biol. Membrany,5, No. 12, 1297–1303 (1988).Google Scholar
  20. 20.
    H. Reuter and C. F. Stevens, “Ion conductance and ion selectivity of potassium channels in snail neurons,”J. Membrane Biol.,57, 103–118 (1980).Google Scholar
  21. 21.
    C. L. Johnson, T. A. Kuntzweiler, J. B. Lingrel, et al., “Glutamic acid 327 in the sheep alpha 1 isoform of Na+, K+-ATPase is a pivotal residue for cation-induced conformational changes,”Biochem. J.,309, 187–194 (1995).Google Scholar
  22. 22.
    A. L. F. Gorman, J. C. Woolum, and M. C. Cornwall, “Selectivity of the Ca2+-activated and light-dependent K+ channels for monovalent cations,”Biophs. J.,38, 319–322 (1982).Google Scholar
  23. 23.
    A. Hermann and A. L. F. Gormann, “Effects of tetraethylammonium on potassium currents in molluscan neurone,”J. Gen. Physiol.,78, 87–110 (1978).Google Scholar
  24. 24.
    D. A. Baxter and J. H. Byrne, “Differential effects of cAMP and serotonin on membrane current, action potential duration, and excitability in somata of pleural sensory neurons ofAplysia,”J. Neurophysiol.,64, No. 3, 978–990 (1990).Google Scholar
  25. 25.
    D. J. Adams, S. J. Smith, and S. H. Thompson, “Ionic currents in molluscan soma,”Annu. Rev. Neurosci.,3, 141–167 (1980).Google Scholar
  26. 26.
    H. Chagneux, C. Ducreux, and M. Gola, “Voltage-dependent opening of single calcium-activated potassium channels inHelix neurons,”Brain Res.,488, No. 1/2, 336–340 (1989).Google Scholar
  27. 27.
    M. Gola, C. Ducreux, and H. Chagneux, “Ca2+-activated K+ current involvement in neuronal function revealed byin situ single-channel analysis inHelix neurons,”J. Physiol.,420, 73–109 (1990).Google Scholar
  28. 28.
    H. D. Lux, E. Neher, and A. Marty, “Single channel activity associated with the calcium-dependent outward current inHelix pomatia,”Pflügers Arch.,389, 293–295 (1981).Google Scholar
  29. 29.
    N. S. Cook, “The pharmacology of potassium channels and their therapeutic potential,”Trends Biochem. Sci.,9, 21–28 (1988).Google Scholar
  30. 30.
    N. A. Castle, D. G. Haylett, and D. H. Jenkinson, “Toxins in the characterization of potassium channels,”Trends Neurosci.,12, 59–65 (1989).Google Scholar
  31. 31.
    Y. Furukawa and M. Kobayashi, “Two serotonin-sensitive potassium channels in the identified heart excitatory neurone of the African giant snail,Achatina fulica Ferussac,”Experientia,44, No. 9, 738–740 (1988).Google Scholar

Copyright information

© Plenum Publishing Corporation 1997

Authors and Affiliations

  • E. A. Lukyanetz
    • 1
  • A. V. Sotkis
    • 1
  1. 1.Bogomolets Institute of PhysiologyNational Academy of Sciences of UkraineKievUkraine

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