Pflügers Archiv

, Volume 400, Issue 1, pp 8–13 | Cite as

Presynaptic currents in frog motor endings

  • A. Mallart
Excitable Tissues And Central Nervous Physiology

Abstract

Membrane currents were recorded from nonmyelinated frog endings by external electrodes. Changes in shape of the signals recorded at varying distances from the myelin end could be explained by assuming a non uniform distribution of Na and K channels along the presynaptic terminal. Specific channel blocking agents revealed that Na channels are present in highest density in the first half of each terminal branch and at almost undetectable levels near the extreme end, while K channels show a more widespread distribution with higher density at medial parts. Suppression of K conductance revealed Ca current which was seen as outward current near the myelin end.

Key words

Motor endings Ionic channel Membrane currents 

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References

  1. Atwood HL (1976) Organization and synaptic physiology of crustacean neuromuscular systems. Progr Neurobiol 7:291–391Google Scholar
  2. Benoit PR, Mabrini J (1970) Modification of transmitter release by ions which prolong the presynaptic action potential. J Physiol (Lond) 210:681–695Google Scholar
  3. Bostock H, Searts TA, Sherratt RM (1981) The effects of 4-aminopyridine and tetraethylammonium ions normal and demyelinated mammalian nerve fibres. J Physiol (Lond) 313:301–315Google Scholar
  4. Braun M, Schmidt RF (1966) Potential changes recorded from the motor nerve terminal during its activation. Pflügers Arch 287:56–80Google Scholar
  5. Brigant JL, Mallart A (1982) Presynaptic currents in mouse motor endings. J Physiol (Lond) 333:619–636Google Scholar
  6. Brismar T (1980) Potential clamp analysis of membrane currents in rat myelinated nerve fibres. J Physiol (Lond) 298:171–184Google Scholar
  7. Burley ES, Jacobs RS (1981) Effects of 4-aminopyridine on nerve terminal action potentials. J Pharmacol Exper Ther 219:268–273Google Scholar
  8. Chiu SY, Ritchie JM, Rogart RB, Stagg D (1979) A quantitative description of membrane currents in rabbit myelinated nerve. J Physiol (Lond) 292:149–166Google Scholar
  9. Dudel J (1982) Transmitter release by graded local depolarization of presynaptic nerve terminals at the crayfish neuromuscular junction. Neurosci Lett 32:181–186Google Scholar
  10. Eccles JC (1964) The physiology of synapses. Academic Press, New York, p 124Google Scholar
  11. Gundersen CB, Katz B, Miledi R (1982) The antagonism of botulinium toxin and calcium in motor nerve terminals. Proc R Soc Lond B 216:369–376Google Scholar
  12. Hodgkin AL, Huxley AF (1952) A quantitative description of membrane currents and its application to conduction and excitation in nerve. J Physiol (Lond) 117:500–544Google Scholar
  13. Katz B, Miledi R (1965) Propagation of electric activity in motor nerve terminals. Proc R Soc (Lond) B 161:453–482Google Scholar
  14. Katz B, Miledi R (1968) The effect of local blockage of motor nerve terminals. J Physiol (Lond) 199:729–741Google Scholar
  15. Kirsch GE, Narahashi T (1978) 3,4-diaminopyridine. A potent new potassium channel blocker. Biophys J 22:507–512Google Scholar
  16. Landh H, Thesleff S (1977) The mode of action of 4-aminopyridine and guanidine on transmitter release from motor nerve terminals. Eur J Pharmacol 42:411–412Google Scholar
  17. Mallart A, Brigant JL (1982) Electrical activity at motor nerve terminals of the mouse. J Physiol (Paris) 78:407–411Google Scholar
  18. Molgo J (1982) Effects of aminopyridines in neuromuscular transmission. In: Bowman WC, Lechat P, Thesleff S (eds) Aminopyridines and similary acting drugs. Pergamon Press, Oxford, p 95Google Scholar
  19. Smith KJ, Schauf CL (1981) Size dependent variation of nodal properties in myelinated nerve. Nature Lond 293:297–298Google Scholar
  20. Stämpfli R, Hille B (1976) Electrophysiology of the peripheral nerve. In: Llinás R, Precht W (eds) Frog neurobiology. Springer, Berlin Heidelberg New York, p 3Google Scholar
  21. Thieffry M, Bruner J (1978) Direct evidence for a presynaptic action of glutamate at a crayfish neuromuscular junction. Brain Res 156:402–406Google Scholar
  22. Zucker R (1974) Crayfish neuromuscular facilitation activated by constrant presynaptic action potentials and depolarizing pulses. J Physiol (Lond) 241:69–89Google Scholar

Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • A. Mallart
    • 1
  1. 1.Unité de Physiologie Neuromusculaire, Laboratoire de Neurobiologie CellulaireC.N.R.SGif-sur-YvetteFrance

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