Skip to main content

Poneratoxin, a new toxin from an ant venom, reveals an interconversion between two gating modes of the Na channels in frog skeletal muscle fibres


The effects of synthetic poneratoxin (PoTX), a new toxin isolated from the venom of the ant Paraponera clavata, were studied under current- and voltage-clamp conditions in frog skeletal muscle fibres. PoTX induces a concentration-dependent (10−9 M–5×10−6 M) prolongation of the action potentials and, at saturating concentration, a slow repetitive activity developing at negative potentials. PoTX specifically acts on voltage-dependent Na channels by decreasing the peak Na current (I Na) and by simultaneously inducing a slow I Na which starts to activate at −85 mV and inactivates very slowly. Both the fast and the slow components of I Na are suppressed by tetrodotoxin and reverse at the same potential corresponding to the equilibrium potential for Na ions. The fast component of I Na has voltage dependence, activation and steady-state inactivation almost similar to those of the control I Na. The voltage dependence of the slow Na conductance is 40 mV more negative than that of the fast one. The results suggest that PoTX affects all the Na channels and that the fast and the slow I Na components originate from a possible PoTX-induced interconversion between a fast and a slow operating mode of the Na channels.

This is a preview of subscription content, access via your institution.


  1. 1.

    Benoit E, Corbier A, Dubois JM (1985) Evidence for two transient sodium currents in the frog node of Ranvier. J Physiol (Lond) 361:339–360

    Google Scholar 

  2. 2.

    Benoit E, Legrand AM, Dubois JM (1986) Effects of ciguatoxin on current and voltage clamped frog myelinated nerve fibre. Toxicon 24:357–364

    Google Scholar 

  3. 3.

    Cahalan MD (1975) Modification of sodium channel gating in frog myelinated nerve fibres by Centruroides sculpturatus scorpion venom. J Physiol (Lond) 244:511–534

    Google Scholar 

  4. 4.

    Duval A, Malécot CO, Pelhate M, Rochat H (1989) Changes in Na channel properties of frog and rat skeletal muscles induced by the AaH II toxin from the scorpion Androctonus australis. Pflügers Arch 415:361–371

    Google Scholar 

  5. 5.

    Duval A, Malécot CO, Pelhate M, Piek T (1991) Poneratoxin (PoTX) converts fast voltage-dependent Na channels into slow operating ones at negative potentials. Pestic Sci 32:374–375

    Google Scholar 

  6. 6.

    Eitan M, Fowler E, Herrmann R, Duval A, Pelhate M, Zlotkin E (1990) A scorpion venom neurotoxin paralytic to insects that affects sodium current inactivation: purification, primary structure, and mode of action. Biochemistry 29:5941–5947

    Google Scholar 

  7. 7.

    Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100

    Google Scholar 

  8. 8.

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

    Google Scholar 

  9. 9.

    Khodorov BI (1985) Batrachotoxin as a tool to study voltage-sensitive Na channels of excitable membranes. Prog Biophys Mol Biol 45:57–148

    Google Scholar 

  10. 10.

    Malécot CO, Duval A (1992) A macro cell-attached patch-clamp study of the properties of the Na current in the vicinity of the motor endplate region of frog single interosseal skeletal muscle fibres. Pflügers Arch 420:231–238

    Google Scholar 

  11. 11.

    Patlak JB, Ortiz M (1986) Two modes of gating during late Na+ channel currents in frog sartorius muscle. J Gen Physiol 87:305–326

    Google Scholar 

  12. 12.

    Piek T (1990) Neurotoxins from venoms of the Hymenoptera — Twenty-five years of research in Amsterdam. Comp Biochem Physiol [C] 96:223–233

    Google Scholar 

  13. 13.

    Piek T, Duval A, Hue B, Karst H, Lapied B, Mantel P, Nakajima T, Pelhate M, Schmidt JO (1991) Poneratoxin, a novel peptide neurotoxin from the venom of the ant, Paraponera clavata. Comp Biochem Physiol [C] 99:487–495

    Google Scholar 

  14. 14.

    Piek T, Hue B, Mantel P, Nakajima T, Schmidt JO (1991) Pharmacological characterization and chemical fractionation of the venom of the ponerine ant, Paraponera clavata (F.). Comp Biochem Physiol [C] 99:481–486

    Google Scholar 

  15. 15.

    Schmidt JO (1986) Chemistry, pharmacology and chemical ecology of ant venoms. In: Piek T (ed) Venom of the Hymenoptera (Chap 9). Academic Press, London, pp 425–508

    Google Scholar 

  16. 16.

    Schmidt JO, Slum MS, Overal WL (1984) Hemolytic activities of stinging insect venoms. Arch Insect Biochem Physiol 1:155–160

    Google Scholar 

  17. 17.

    Treherne JE (1985) Blood-Brain Barrier. In: Kerkut GA, Gilbert LI (eds) Comprehensive insect physiology biochemistry and pharmacology (vol 5). Nervous system: structure and motor function. Pergamon, Oxford New York Toronto Sydney Paris Frankfurt, pp 115–137

    Google Scholar 

  18. 18.

    Vijverberg HPM, Pauron D, Lazdunski M (1984) The effect of Tityus serrulatus scorpion toxin γ on Na channels in neuroblastoma cells. Pflügers Arch 401:297–303

    Google Scholar 

  19. 19.

    Wang GK, Strichartz G (1985) Kinetic analysis of the action of Leiurus scorpion α-toxin on ionic currents in myelinated nerve. J Gen Physiol 86:739–762

    Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Claire O. Malécot.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Duval, A., Malécot, C.O., Pelhate, M. et al. Poneratoxin, a new toxin from an ant venom, reveals an interconversion between two gating modes of the Na channels in frog skeletal muscle fibres. Pflügers Arch 420, 239–247 (1992).

Download citation

Key words

  • Skeletal muscle
  • Ant toxin
  • Poneratoxin
  • Na channels
  • Fast and slow gating modes