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Presynaptic currents in frog motor endings

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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.

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References

  1. Atwood HL (1976) Organization and synaptic physiology of crustacean neuromuscular systems. Progr Neurobiol 7:291–391

  2. Benoit PR, Mabrini J (1970) Modification of transmitter release by ions which prolong the presynaptic action potential. J Physiol (Lond) 210:681–695

  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) 313:301–315

  4. Braun M, Schmidt RF (1966) Potential changes recorded from the motor nerve terminal during its activation. Pflügers Arch 287:56–80

  5. Brigant JL, Mallart A (1982) Presynaptic currents in mouse motor endings. J Physiol (Lond) 333:619–636

  6. Brismar T (1980) Potential clamp analysis of membrane currents in rat myelinated nerve fibres. J Physiol (Lond) 298:171–184

  7. Burley ES, Jacobs RS (1981) Effects of 4-aminopyridine on nerve terminal action potentials. J Pharmacol Exper Ther 219:268–273

  8. Chiu SY, Ritchie JM, Rogart RB, Stagg D (1979) A quantitative description of membrane currents in rabbit myelinated nerve. J Physiol (Lond) 292:149–166

  9. Dudel J (1982) Transmitter release by graded local depolarization of presynaptic nerve terminals at the crayfish neuromuscular junction. Neurosci Lett 32:181–186

  10. Eccles JC (1964) The physiology of synapses. Academic Press, New York, p 124

  11. Gundersen CB, Katz B, Miledi R (1982) The antagonism of botulinium toxin and calcium in motor nerve terminals. Proc R Soc Lond B 216:369–376

  12. Hodgkin AL, Huxley AF (1952) A quantitative description of membrane currents and its application to conduction and excitation in nerve. J Physiol (Lond) 117:500–544

  13. Katz B, Miledi R (1965) Propagation of electric activity in motor nerve terminals. Proc R Soc (Lond) B 161:453–482

  14. Katz B, Miledi R (1968) The effect of local blockage of motor nerve terminals. J Physiol (Lond) 199:729–741

  15. Kirsch GE, Narahashi T (1978) 3,4-diaminopyridine. A potent new potassium channel blocker. Biophys J 22:507–512

  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 42:411–412

  17. Mallart A, Brigant JL (1982) Electrical activity at motor nerve terminals of the mouse. J Physiol (Paris) 78:407–411

  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 95

  19. Smith KJ, Schauf CL (1981) Size dependent variation of nodal properties in myelinated nerve. Nature Lond 293:297–298

  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 3

  21. Thieffry M, Bruner J (1978) Direct evidence for a presynaptic action of glutamate at a crayfish neuromuscular junction. Brain Res 156:402–406

  22. Zucker R (1974) Crayfish neuromuscular facilitation activated by constrant presynaptic action potentials and depolarizing pulses. J Physiol (Lond) 241:69–89

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Correspondence to A. Mallart.

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Mallart, A. Presynaptic currents in frog motor endings. Pflugers Arch. 400, 8–13 (1984). https://doi.org/10.1007/BF00670529

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Key words

  • Motor endings
  • Ionic channel
  • Membrane currents