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Potential changes recorded from the frog motor nerve terminal during its activation

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Zusammenfassung

1. Aktive synaptische Stellen auf Endplatten von Nerv-Muskel-Präparaten (meistens M. cutaneus pectoris) des Frosches wurden durch extracelluläre Ableitung von min.e.p.p. identifiziert. Zur Lokalisation der Endigungen wurde ein stark vergrößerndes Präpariermikroskop und durchfallende Beleuchtung benützt.

2. Das präsynaptische Nervenaktionspotential (PNAP) konnte nach orthodromer Reizung von aktiven synaptischen Stellen als kleine Potentialschwankung vor dem e.p.p. abgeleitet werden. Das PNAP war nahe dem markhaltigen Motoaxon triphasisch, positiv-negativ-positiv, mit einem überwiegend negativen Anteil, während es gegen das Ende der marklosen Fasern mehr und mehr einphasisch positiv wurde.

3. Die Leitungsgeschwindigkeit des PNAP hatte ihren kleinsten Wert am Übergang vom markhaltigen Axon zu den marklosen Zweigen und nahm dann im Verlauf der marklosen Fasern wieder zu. Die durchschnittliche Leitungsgeschwindigkeit im Verlauf der gesamten Endplatte betrug etwa 30 cm/sec.

4. Während tetanischer Reizung mit mehr als 5 Hz war das PNAP fast immer kleiner als sein Kontrollwert bei 1 Hz, während das e.p.p. die erwartete Zunahme zeigte. Die jeweilige Größe des PNAP hing ab von: der Reizfrequenz, der Zahl der vorhergegangenen Reize und von der Mg-Konzentration der Badelösung.

5. Nach Reizung blieb das PNAP zunächst klein und kehrte dann innerhalb 30–60 msec nach Einzelreiz bis zu einigen hundert msec nach langer tetanischer Reizung zur ursprünglichen Amplitude zurück. Das verkleinerte PNAP war nicht von einem anschließenden vergrößerten PNAP gefolgt.

6. Wurden aktive synaptische Stellen durch die Mikroelektrode gereizt, so konnte bei 30% aller Stellen ein antidromes Aktionspotential ausgelöst werden. Der Verlauf der Erregbarkeit nach einem Vorreiz wurde untersucht.

7. Aus diesen Versuchen wurde geschlossen: a) das PNAP wird aktiv in die marklosen Nervenfasern der Endplatte hinein- und mindestens über weite Strecken auch aktiv weitergeleitet; b) während und nach tetanischer Reizung wird die Amplitude des PNAP durch negative Nachpotentiale (Nachdepolarisationen), die sich bei repetitiver Reizung addieren, reduziert; c) die Größe des PNAP scheint keinen entscheidenden Einfluß auf die Menge des ACh zu haben, das durch einen präsynaptischen Impuls freigesetzt wird.

Summary

1. Active synaptic regions were identified in Mg-blocked nerve-muscle preparations (mainly M. cutaneous pectoris) of the frog by the recording of extracellular min.e.p.p.s. The search for these regions was helped by the use of high power dissecting microscopes and transmitted illumination.

2. E.p.p.s evoked by orthodromic stimulation and recorded at active synaptic regions were preceded by small all-or-nothing potential changes, the presynaptic nerve action potential (PNAP). Near the myelinated portion of the motor axon the PNAP had a triphasic positive-negative-positive shape with a predominantly negative deflection, whereas towards the ultimate end of the terminal the PNAP became more and more monophasic positive.

3. The conduction velocity of the PNAP was minimal near the transition from the myelinated axon to the non-myelinated nerve twigs and increased towards the end of the motor nerve terminal. The overall conduction velocity was around 30 cm/sec.

4. During repetitive stimulation at frequencies above 5/sec the PNAP was almost always smaller than its control value at 1/sec, whereas the e.p.p. showed the expected increase in amplitude. The actual size of the PNAP depended on the frequency of stimulation, on the number of preceding volleys, and on the Mg-concentration of the bathing solution.

5. After stimulation the PNAP remained depressed for periods from 30–60 msec after a single stimulus to some hundreds of msec after prolonged stimulation. There was no period of an increased PNAP following the period of the reduced PNAP.

6. Stimulating active synaptic regions through the recording microelectrode resulted in 30% of the trials in the appearance of antidromic spike potentials. The excitability cycle was investigated following single conditioning pulses.

7. It was concluded that: a) the PNAP actively invaded nerve terminals and was actively conducted over most of the length of the non-myelinated nerve twigs; b) negative afterpotentials (afterdepolarizations) which built up considerably during repetitive stimulation, reduced the size of the PNAP during and after tetanic trains; c) the size of the PNAP did not play a significant role in determining the amount of transmitter released by a presynaptic impulse.

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References

  • Armett, C. J., and J. M. Ritchie: The action of acetylcholine on conduction in mammalian non-myelinated fibres and its prevention by an anticholinesterase. J. Physiol. (Lond.) 152, 141–158 (1960).

    Google Scholar 

  • — The action of acetylcholine and some related substances on conduction in mammalian non-myelinated nerve fibres. J. Physiol. (Lond.) 155, 372–384 (1961).

    Google Scholar 

  • Birks, R. I.: The role of sodium ions in the metabolism of acetylcholine. Canad. J. Biochem. 41, 2573–2597 (1963).

    Google Scholar 

  • Braun, M., u. R. F. Schmidt: Präsynaptische Aktionspotentiale der neuromuskulären Endplatte des Frosches. Pflügers Arch. ges. Physiol. 281, 21–22 (1964).

    Google Scholar 

  • -- -- Präsynaptische Veränderungen an der motorischen Endplatte des Frosches nach repetitiver Reizung. Pflügers Arch. ges. Physiol. 283, R41 (1965).

  • —, and M. Zimmermann: Facilitation at the frog neuromuscular junction during and after repetitive stimulation. Pflügers Arch. ges. Physiol. 287, 41–55 (1966).

    Google Scholar 

  • Brooks, C. McC., and J. C. Eccles: Electrical investigation of the monosynaptic pathway through the spinal cord. J. Neurophysiol. 10, 251–274 (1947).

    Google Scholar 

  • Brown, G. L., and O. Holmes: The effects of activity on mammalian nerve fibres of low conduction velocity. Proc. roy. Soc. B 145, 1–14 (1956).

    Google Scholar 

  • Cole, W. V.: Structural variations of nerve endings in the striated muscles of the rat. J. comp. Neurol. 108, 445–464 (1957).

    Google Scholar 

  • Dettbarn, W. D., and F. A. Davis: Effect of acetylcholine on axonal conduction of lobster nerve. Biochem. biophys. Acta (Amst.) 66, 397–405 (1963).

    Google Scholar 

  • Dudel, J.: Presynaptic inhibition of the excitatory nerve terminal in the neuromuscular junction of the crayfish. Pflügers Arch. ges. Physiol. 277, 537–557 (1963).

    Google Scholar 

  • — Die synaptische Bahnung nach einer Reizserie am Krebsmuskel. Pflügers Arch. ges. Physiol. 281, 29 (1964).

    Google Scholar 

  • — Potential changes in the crayfish motor nerve terminal during repetitive stimulation. Pflügers Arch. ges. Physiol. 282, 323–337 (1965).

    Google Scholar 

  • —, and S. W. Kuffler: The quantal nature of transmission and spontaneous miniature potentials at the crayfish neuromuscular junction. J. Physiol. (Lond.) 155, 514–529 (1961).

    Google Scholar 

  • Eccles, J. C.: The neurophysiological basis of mind. The principles of neurophysiology. Oxford: Clarendon Press 1953.

    Google Scholar 

  • — The Physiology of Nerve Cells. Baltimore: John Hopkins Press 1957.

    Google Scholar 

  • — The Physiology of Synapses. Berlin, Göttingen, Heidelberg: Springer 1964.

    Google Scholar 

  • — P. G. Kostyuk, and R. F. Schmidt: The effect of electric polarization of the spinal cord on central afferent fibres and on their excitatory synaptic action. J. Physiol. (Lond.) 162, 138–150 (1962).

    Google Scholar 

  • —, and K. Krnjević: Presynaptic changes associated with post-tetanic potentiation in the spinal cord. J. Physiol. (Lond.) 149, 274–287 (1959).

    Google Scholar 

  • —, and W. Rall: Effects induced in a monosynaptic reflex path by its activation. J. Neurophysiol. 14, 353–376 (1951).

    Google Scholar 

  • Ecker, A.: Anatomie des Frosches. Braunschweig: Fr. Vieweg und Sohn 1888.

    Google Scholar 

  • Ehrenpreis, S.: Acetylcholine and nerve activity. Nature (Lond.) 201, 887–893 (1964).

    Google Scholar 

  • Erlanger, J., and H. S. Gasser: Electrical signs of nervous activity. Philadelphia: University of Pennsylvania Press 1937.

    Google Scholar 

  • Frankenhaeuser, B., and A. L. Hodgkin: The after-effects of impulses in the giant axon of Loligo. J. Physiol. (Lond.) 131, 341–376 (1956).

    Google Scholar 

  • Graham, H. T.: Supernormality, a modification of the recovery process in nerve. Amer. J. Physiol. 110, 225 (1934).

    Google Scholar 

  • Greengard, P., and R. W. Straub: After-potentials in mammalian non-myelinated nerve fibres. J. Physiol. (Lond.) 144, 442–462 (1958).

    Google Scholar 

  • Grundfest, H., and H. S. Gasser: Properties of mammlian nerve fibres of slowest conduction. Amer. J. Physiol. 123, 307–318 (1938).

    Google Scholar 

  • Hagiwara, S., and I. Tasaki: A study of the mechanism of impulse transmission across the giant synapse of the squid. J. Physiol. (Lond.) 143, 114–137 (1958).

    Google Scholar 

  • Holmes, O.: Effects of pH, changes in potassium concentration and metabolic inhibitors on the after-potentials of mammalian non-medullated nerve fibres. Arch. int. Physiol. 70, 211–245 (1962).

    Google Scholar 

  • Hubbard, J. I.: Repetitive stimulation at the mammalian neuromuscular junction, and the mobilization of transmitter. J. Physiol. (Lond.) 169, 641–662 (1963).

    Google Scholar 

  • —, and R. F. Schmidt: An electrophysiological investigation of mammalian motor nerve terminals. J. Physiol. (Lond.) 166, 145–165 (1963).

    Google Scholar 

  • Hubbard, J. I., R. F. Schmidt, and T. Yokota: The effect of acetylcholine upon mammalian motor nerve terminals. J. Physiol. (Lond.) (in press) (1965).

  • Katz, B.: The transmission of impulses from nerve to muscle, and the subcellular unit of synaptic action. Proc. roy. Soc. B 155, 455–479 (1962).

    Google Scholar 

  • —, and R. Miledi: Propagation of electric activity in motor nerve terminals. Proc. roy. Soc. B 161, 453–482 (1965a).

    Google Scholar 

  • — The measurement of synaptic delay, and the time course of acetylcholine release at the neuromuscular junction. Proc. roy. Soc. B 161, 483–495 (1965b).

    Google Scholar 

  • — The effect of calcium on acetylcholine release from motor nerve terminals. Proc. roy. Soc. B 161, 496–503 (1965c).

    Google Scholar 

  • Liley, A. W.: The effects of presynaptic polarization on the spontaneous activity at the mammalian neuromuscular junction. J. Physiol. (Lond.) 134, 427–443 (1956).

    Google Scholar 

  • Lloyd, D. P. C.: Post-tetanic potentiation of response in monosynaptic reflex pathways of the spinal cord. J. gen. Physiol. 33, 147–170 (1949).

    Google Scholar 

  • Lorente de Nó, R.: A study of nerve physiology I + II. Stud. Rockefeller Inst. med. Res. 131 (1947); 132 (1947).

  • Martin, A. R., and G. Pilar: Presynaptic and post-synaptic events during post-tetanic potentiation and facilitation in the avian ciliary ganglion. J. Physiol. (Lond.) 175, 17–30 (1964).

    Google Scholar 

  • McLennan, H.: Synaptic Transmission. Philadelphia: W. B. Sauders Co. 1963.

    Google Scholar 

  • Ritchie, J. M., and C. J. Armett: On the role of acetylcholine in conduction in mammalian non-myelinated nerve fibers. J. Pharmacol. exp. Ther. 139, 201–207 (1963).

    Google Scholar 

  • —, and R. W. Straub: The after-effects of repetitive stimulation on mammalian non-medullated fibres. J. Physiol. (Lond.) 134, 698–711 (1956).

    Google Scholar 

  • Shanes, A. M.: Electrical phenomena in nerve. I. Squid giant axon. J. gen. Physiol. 33, 57–73 (1949a).

    Google Scholar 

  • — Electrical phenomena in nerve. II. Crab nerve. J. gen. Physiol. 33, 75–102 (1949b).

    Google Scholar 

  • — Potassium movements in relation to nerve activity. J. gen. Physiol. 34, 795–807 (1951).

    Google Scholar 

  • Takeuchi, A., and N. Takeuchi: Electrical changes in pre- and postsynaptic axons of the giant synapse of Loligo. J. gen. Physiol. 45, 1181–1193 (1962).

    Google Scholar 

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Authors and Affiliations

  1. Institut für Allgemeine Physiologie der Universität Heidelberg, Germany

    M. Braun & R. F. Schmidt

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  1. M. Braun
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  2. R. F. Schmidt
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With 9 Figures in the Text

This work was supported by the Deutsche Forschungsgemeinschaft.

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Braun, M., Schmidt, R.F. Potential changes recorded from the frog motor nerve terminal during its activation. Pflügers Archiv 287, 56–80 (1966). https://doi.org/10.1007/BF00362454

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