The Journal of Membrane Biology

, Volume 64, Issue 1–2, pp 55–66 | Cite as

Effects of divalent cations on toad end-plate channels

  • Ken Takeda
  • Peter W. Gage
  • Peter H. Barry


Miniature end-plate currents (MEPCs) and acetylcholine-induced current fluctuations were recorded in voltageclamped, glycerol-treated toad sartorius muscle fibers in control solution and in solutions with added divalent cations. In isosmotic solutions containing 20mm Ca or Mg, MEPCs had time constants of decay (τ D ) which were about 30% slower than normal. In isotonic Ca solutions (Na-free), greater increases in both τ D and channel lifetime were seen; the null potential was −34 mV, and single-channel conductance decreased to approximately 5 pS. Zn or Ni, at concentrations of 0.1–5mm, were much more effective in increasing τ D than Ca or Mg, although they did not greatly affect channel conductance. The normal temperature and voltage sensitivity of τ was not significantly altered by any of the added divalent cations. Surface potential shifts arising from screening of membrane fixed charge by divalent cations cannot entirely explain the observed increases in τ, especially when taken together with changes in channel conductance.

Key words

endplate channel divalent cations AChnoise calcium 


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  1. Adams, D.J., Dwyer, T.M., Hille, B. 1980. The permeability of end-plate channels to monovalent and divalent metal cations.J. Gen. Physiol. 75:493–510PubMedGoogle Scholar
  2. Adams, P.R. 1976. Drug blockade of open end-plate channels.J. Physiol. (London) 260:531–552Google Scholar
  3. Adams, P.R., 1977. Voltage jump analysis of procaine action at frog end-plate.J. Physiol. (London) 268:291–318Google Scholar
  4. Adams, P.R., Sakmann, B. 1978. Decamethonium both opens and blocks end-plate channels.Proc. Natl. Acad. Sci. USA 75:2994–2998PubMedGoogle Scholar
  5. Anderson, C.R., Stevens, C.F. 1973. Voltage clamp analysia of acetylcholine produced end-plate current fluctuations at frog neuromuscular junction.J. Physiol. (London) 235:655–691Google Scholar
  6. Armstrong, C.M. 1975. Channels and voltage dependent gates in nerve.In: Membranes — A Series of Advances. Artificial and Biological Membranes. G. Eisenman, editor. Vol. 3, pp. 325–358. Marcel Dekker, N.Y.Google Scholar
  7. Armstrong, C.M., Gilly, W.F. 1979. Fast and slow steps in the activation of sodium channels.J. Gen. Physiol. 74:691–711PubMedGoogle Scholar
  8. Ascher, P., Marty, A., Neild, T.O. 1978. Lifetime and elementary conductance of the channels mediating the excitatory effects of acetylcholine inAplysia neurones.J. Physiol. (London) 278:177–206Google Scholar
  9. Bamberg, E., Läuger, P. 1977. Blocking of the Gramicidin channel by divalent cations.J. Membrane Biol. 35:351–375Google Scholar
  10. Barry, P.H., Gage, P.W., Van Helden, D.F. 1979a. Cation permeation at the amphibian motor end-plate.J. Membrane Biol. 45:245–276Google Scholar
  11. Barry, P.H., Gage, P.W., Van Helden, D.F. 1979b. Cation permeation through single end-plate channels.Excerpta Med. Int. Congr. Ser. 473:174–184Google Scholar
  12. Begenisich, T., Lynch, C. 1974. Effects of internal divalent cations on voltage-clamped squid axons.J. Gen. Physiol. 63:675–689Google Scholar
  13. Blaustein, M.P., Goldman, D.E. 1968. The action of certain polyvalent cations on the voltage-clamped lobster axon.J. Gen. Physiol. 51:279–291PubMedGoogle Scholar
  14. Bregestovski, P.D., Miledi, R., Parker, I. 1979. Calcium conductance of acetylcholine induced end-plate channels.Nature (London) 279:638–639Google Scholar
  15. Cohen, I., Van der Kloot, W.G. 1978. Effects of [Ca2+] and [Mg2+] on the decay of miniature end-plate currents.Nature (London) 271:77–79Google Scholar
  16. Dwyer, T.M., Adams, D.J., Hille, B. 1980. The permeability of end-plate channels to organic cations in frog muscle.J. Gen. Physiol. 75:469–492PubMedGoogle Scholar
  17. Frankenhaeuser, B., Hodgkin, A.L. 1957. The action of calcium on the electrical properties of squid axons.J. Physiol. (London) 137:218–244Google Scholar
  18. Gage, P.W., McBurney, R.N. 1975. Effects of membrane potential, temperature and neostigmine on the conductance change caused by a quantum of acetylcholine at the toad neuromuscular junction.J. Physiol. (London) 244:385–407Google Scholar
  19. Gage, P.W., McBurney, R.N., Van Helden, D.F. 1978. Octanol reduces end-plate channel lifetime.J. Physiol. (London) 274:279–298Google Scholar
  20. Gage, P.W., Van Helden, D.F. 1979. Effects of permeant monovalent cations on end-plate channels.J. Physiol. (London) 288:509–528Google Scholar
  21. Grahame, D.C. 1947. The electrical double layer and the theory of electrocapillarity.Chem. Rev. 41:441–501CrossRefGoogle Scholar
  22. Hille, B., Woodhull, A.M., Shapiro, B.I. 1975. Negative surface charge near sodium channels of nerve: Divalent ions, monovalent ions and pH.Philos. Trans. R. Soc. London B. 270:301–318Google Scholar
  23. Katz, B., Miledi, R. 1969. Spontaneous and evoked activity of motor nerve endings in calcium Ringer.J. Physiol. (London) 203:689–706Google Scholar
  24. Katz, B., Miledi, R. 1973. The binding of acetylcholine to receptors and its removal from the synaptic cleft.J. Physiol. (London) 231:549–574Google Scholar
  25. Kehoe, J.S. 1972. Ionic mechanisms of a two-component cholinergic inhibition inAplysia neurones.J. Physiol. (London) 225:85–114Google Scholar
  26. Kolb, H.A., Bamberg, E. 1977. Influence of membrane thickness and ion concentration on the properties of the Gramicidin A channel. Autocorrelation, spectral power density, relaxation and single channel properties.Biochim. Biophys. Acta 464:127–141PubMedGoogle Scholar
  27. Lewis, C.A. 1979. Ion-concentration dependence of the reversal potential and the single channel conductance of ion channels at the frog neuromuscular junction.J. Physiol. (London) 286:417–445Google Scholar
  28. Lewis, C.A., Stevens, C.F. 1979. Mechanism of ion permeation through channels in a postsynaptic membrane.In: Membrane Transport Processes. C.F. Stevens, and R.W. Tsien, editors. Vol. 3, pp. 133–151. Raven Press, N.Y.Google Scholar
  29. Linder, T.M., Quastel, D.M.J. 1978. A voltage-clamp study of the permeability change induced by quanta of transmitter at the mouse end-plate.J. Physiol. (London) 281:535–556Google Scholar
  30. Magleby, K.L., Stevens, C.F. 1972 A quantitative description of end-plate currents.J. Physiol. (London) 223:173–197Google Scholar
  31. Magleby, K.L., Weinstock, M.M. 1980. Nickel and calcium ions modify the characteristics of the acetylcholine receptor-channel complex at the frog neuromuscular junction.J. Physiol. (London) 299:203–218Google Scholar
  32. Mallart, A., Molgó, J. 1978. The effects of pH and curare on the time course of end-plate currents at the neuromuscular junction of the frog.J. Physiol. (London) 276:343–352Google Scholar
  33. Marchais, D., Marty, A. 1979. Interaction of permeant ions with channels activated by acetylcholine inAplysia neurones.J. Physiol. (London) 297:9–45Google Scholar
  34. McLaughlin, S.G.A., Szabo, G., Eisenman, G. 1971. Divalent ions and the surface potential of charged phospholipid membranes.J. Gen. Physiol. 58:667–687PubMedGoogle Scholar
  35. Miledi, R., Parker, I. 1980. Effects of strontium ions on end-plate channel properties.J. Physiol. (London) 306:567–577Google Scholar
  36. Neher, E., Steinbach, J.H. 1978. Local anaesthetics transiently block currents through single acetylcholine channels.J. Physiol. (London) 277:153–176Google Scholar
  37. Nonner, W., Adams, D.J., Dwyer, T.M., Hille, B. 1980. Conductance fluctuation measurements with organic cations at the end-plate channel.Fed. Proc. 39:2064Google Scholar
  38. Rang, H.P. 1975. Acetylcholine receptors.Quart. Rev. Biophys. 7:283–399Google Scholar
  39. Ruff, R.L. 1977. A quantitative analysis of local anaesthetic alteration of miniature end-plate currents and end-plate current fluctuations.J. Physiol. (London) 264:89–124Google Scholar
  40. Scuka, M. 1975. The amplitude and the time course of the end-plate current at various pH levels in the frog sartorius muscle.J. Physiol. (London) 249:183–195Google Scholar
  41. Takeda, K., Barry, P.H., Gage, P.W. 1980a. Effects of ammonium ions on end-plate channels.J. Gen. Physiol. 75:589–613PubMedGoogle Scholar
  42. Takeda, K., Barry, P.H., Gage, P.W. 1980b. Divalent cations lengthen channel lifetime at the toad neuromuscular junction.Proc. Aust. Soc. Biophys. 4:2AGoogle Scholar
  43. Takeda, K., Datyner, N.B., Barry, P.H., Gage, P.W. 1978. Postsynaptic effects of Zn2+ at the motor end-plate.Proc. Aust. Physiol. Pharmacol. Soc. 9:126PGoogle Scholar
  44. Takeuchi, A., Takeuchi, N. 1959. Active phase of frog's end-plate potential.J. Neurophysiol. 22:395–411PubMedGoogle Scholar
  45. Takeuchi, A., Takeuchi, N. 1960. On the permeability of end-plate membrane during the action of transmitter.J. Physiol. (London) 154:52–67Google Scholar
  46. Van der Kloot, W.G., Cohen, I. 1979. Membrane surface potential changes may alter drug interactions: An example, acetylcholine and curare.Science 203:1351–1353PubMedGoogle Scholar
  47. Van Helden, D.F., Hamill, O.P., Gage, P.W. 1977. Permeant cations alter end-plate channel characteristics.Nature (London) 269:711–713Google Scholar
  48. Watanabe, S., Narahashi, T. 1979. Cation selectivity of acetylcholine-activated ionic channels of frog end-plate.J. Gen. Physiol. 74:615–628PubMedGoogle Scholar

Copyright information

© Springer-Verlag New York Inc. 1982

Authors and Affiliations

  • Ken Takeda
    • 1
  • Peter W. Gage
    • 1
  • Peter H. Barry
    • 1
  1. 1.School of Physiology and PharmacologyUniversity of New South WalesKensingtonAustralia

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