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.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
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
Benoit E, Legrand AM, Dubois JM (1986) Effects of ciguatoxin on current and voltage clamped frog myelinated nerve fibre. Toxicon 24:357–364
Cahalan MD (1975) Modification of sodium channel gating in frog myelinated nerve fibres by Centruroides sculpturatus scorpion venom. J Physiol (Lond) 244:511–534
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
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
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
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
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
Khodorov BI (1985) Batrachotoxin as a tool to study voltage-sensitive Na channels of excitable membranes. Prog Biophys Mol Biol 45:57–148
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
Patlak JB, Ortiz M (1986) Two modes of gating during late Na+ channel currents in frog sartorius muscle. J Gen Physiol 87:305–326
Piek T (1990) Neurotoxins from venoms of the Hymenoptera — Twenty-five years of research in Amsterdam. Comp Biochem Physiol [C] 96:223–233
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
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
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
Schmidt JO, Slum MS, Overal WL (1984) Hemolytic activities of stinging insect venoms. Arch Insect Biochem Physiol 1:155–160
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
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
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
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). https://doi.org/10.1007/BF00374453
- Skeletal muscle
- Ant toxin
- Na channels
- Fast and slow gating modes