Springer Nature is making Coronavirus research free. View research | View latest news | Sign up for updates

Effect of p-nitrophenyl diazonium fluoroborate on cholinergic mechanisms

  • 14 Accesses

  • 1 Citations


Electrophysiological experiments were done to investigate the effect of p-nitrophenyl diazonium fluoroborate (p-NPD) on motor endplates of the frog's m. cutaneus pectoris. The compound has no direct depolarizing effect on the postsynaptic membrane and stabilizes it irreversibly when added to the bath. Longtime iontophoretical applications of p-NPD produce a biphasic effect: initially a potentiation of the depolarizations due to acetylcholine (ACh) (both iontophoretically applied and presynaptically liberated), and subsequently an inhibition of the response to ACh. When the acetylcholinesterase (AChE) is inactivated previously, only the inhibiting effect of the compound is demonstrable.

The association constant of p-NPD to purified AChE and to membrane fragments of electroplax was determined by biochemical methods. The compound's affinity to the AChE was found to be about 20 times greater than to the acetylcholine receptor (AChR).

Iontophoretical application of p-NPD to cholinergic neurons in the hippocampal cortex of the cat also produced the characteristic biphasic effect on ACh-induced activity of these investigated neurons.

The results suggest that the biphasic effect depends on the capacity of p-NPD to combine with both the AChE and the AChR. The AChE is first inhibited with low concentrations thereby potentiating the ACh response. At higher concentrations the AChR's are progressively inhibited too, thereby diminishing the excitability of the postsynaptic membrane up to a complete block.

This is a preview of subscription content, log in to check access.


  1. Biscoe, T. J., Straughan, D. W.: Microelectrophoretic studies of neurones in cat hippocampus. J. Physiol. (Lond.)183, 341–359 (1966)

  2. Dixon, M., Webb, E. C.: Enzymes, London: Longmans 1964

  3. Ellman, G. L., Courtney, K. D., Andres, V., Featherstone, R. M.: A new and rapid colorimetric determination of acetylcholinesterase activity. Biochem. Pharmacol.7, 88–95 (1961)

  4. Gage, P. W., Eisenberg, R. S.: Action potentials without contraction in frog skeletal muscle fibres with disrupted transverse tubules. Science158, 1702–1703 (1967)

  5. Gage, P. W., Eisenberg, R. S.: Action potentials and excitationcontraction coupling in frog sartorius fibres without transverse tubules. J. gen. Physiol.53, 298–310 (1969)

  6. Herz, A., Wickelmaier, M., Nacimiento, A.: Über die Herstellung von Mehrfachelektroden für die Mikroelektrophorese. Pflügers Arch.284, 95–98 (1965)

  7. Hopff, W. H., Riggio, G., Waser, P. G.: Affinity chromatography of acetylcholine acetyl-hydrolase. FEBS Letters35, 220–222 (1973)

  8. Hopff, W. H., Riggio, G., Waser, P. G.: Progress in isolation of acetylcholinesterase. In: Cholinergic mechanisms. (P. G. Waser, ed.), New York: Raven Press 1975

  9. Kölliker, A.: Untersuchungen über die letzte Endigungen der Nerven. Mit 4 Kupfertafeln. Z. wiss. Zool.XII, 149–164 (1863)

  10. Lebbin, C., Hofmann, A., Waser, P. G.: Affinity-labeling of the muscarinic receptor of the guinea-pig ileum. Naunyn-Schmiedebergs Arch. Pharmac.289, 237–249 (1975)

  11. Lowry, O. H., Rosebrough, N. J., Farr, A. L., Randall, R. J.: Protein measurement with the Folin phenol reagent. J. biol. Chem.193, 265–275 (1951)

  12. McMahan, U. J., Spitzer, N. C., Peper, K.: Visual identification of nerve terminals in living isolated skeletal muscle. Proc. roy. Soc. B181, 421–430 (1972)

  13. Mautner, H. G., Bartels, E.: Interaction of p-nitrobenzene diazonium fluoroborate and analogues with the active site of ACh-receptor and AChE. Proc. nat. Acad. Sci. (Wash.)67, 74–78 (1970)

  14. Nastuk, W. L.: The electrical activity of the muscle cell membrane at the neuromuscular junction. J. cell. comp. Physiol.42, 249–272 (1953)

  15. Neilands, J. B., Cannon, M. D.: Automatic recording pH instrumentation. Industr. Chem. Analytical27, 29–33 (1955)

  16. Peper, K., McMahan, U. J.: Distribution of acetylcholine in the vicinity of nerve terminals on skeletal muscle of the frog. Proc. roy. Soc. B181, 431–440 (1972)

  17. Reichert, K. E.: Über das Verhalten der Nervenfasern bei dem Verlauf, der Vertheilung und Endigung in einem Hautmuskel des Frosches (Rana temporaria). Müller's Arch. Anat. Physiol. 29–73 (1851)

  18. Starkney, E. B.: p-Dinitrobenzene. In: Org. synth. coll. Vol. II, pp. 225–227 (A. H. Blatt, ed.), New York-London: Wiley and Sons 1961

  19. Walser, J. T., Schaub, M. C., Waser, P. G.: Binding studies on membrane fragments of electroplax from Torpedo marmorata. In: Cholinergic Mechanisms. (P. G. Waser, ed.), New York: Raven Press 1975

Download references

Author information

Correspondence to C. G. Caratsch.

Additional information

With the aid of grants No. 3.211.73 and No. 3.534.0.75 of the Swiss National Foundation for Scientific Research.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Caratsch, C.G., Waser, P.G., Spiess, C. et al. Effect of p-nitrophenyl diazonium fluoroborate on cholinergic mechanisms. Naunyn-Schmiedeberg's Arch. Pharmacol. 294, 61–68 (1976).

Download citation

Key words

  • p-Nitrophenyl diazonium fluoroborate
  • Cholinergic neurons
  • Acetylcholine receptor
  • Acetylcholinesterase
  • Affinity labelling