---
_id: '3467'
abstract:
- lang: eng
  text: The effects of mast cell degranulating peptide (MCDP), a toxin from the honey
    bee, and of dendrotoxin (DTX), a toxin from the green mamba snake, were studied
    in voltage-clamped experiments with myelinated nerve fibres of Xenopus. MCDP and
    DTX blocked part of the K+ current. About 20% of the K+ current, however, was
    resistant to the toxins even in high concentrations. In Ringer solution half-maximal
    block was reached with concentrations of 33 nM MCDP and 11 nM DTX. In high-K+
    solution the potency of both toxins was lower. β-Bungarotoxin (β-BuTX), another
    snake toxin, also blocked part of the K+ current, but was less potent than MCDP
    and DTX. Tail currents in high-K+ solution were analysed and three K+ current
    components were separated according to Dubois (1981b). Both MCDP and DTX selectively
    blocked a fast deactivating, slowly inactivating K+ current component which steeply
    activates between E = -60 mV and E = -40 mV (component f1). In concentrations
    around 100 nM, MCDP and DTX blocked neither the slow K+ current (component s)
    nor the fast deactivating, rapidly inactivating K+ current which activates between
    E = -40 mV and E = 20 mV (component f2). Similar results could be derived from
    K+ outward currents in Ringer solution. In high-K+, IC50 of MCDP for component
    f1 was 99 nM, whereas it was 7.6 μM for f2. Corresponding values for DTX are 68
    nM and 1.8 μM. Binding studies with nerve fibre membranes of Xenopus reveal high-affinity
    binding sites for 125I-labelled DTX )K(D) = 22 pM in Ringer solution and 81 pM
    in high-K+ solution). 125I-labelled DTX can be displaced from its sites completely
    by unlabelled DTX, toxin I (black mamba toxin), MCDP, and partially by β-BuTX.
    Immunocytochemical staining demonstrates that binding sites for DTX are present
    in nodal and paranodal regions of the axonal membrane. The axonal membrane of
    motor and sensory nerve fibres is equipped with three types of well-characterized
    K+ channels and constitutes so far the best preparation to study MCDP- and DTX-sensitive
    K+ channels with electrophysiological and biochemical methods.
acknowledgement: "We thank Professor E. Habermann for critical reading of the manuscript
  and E. Schmidt and J. Schafer for technical assistance. Financial support by the
  Deutsche Forschungsgemeinschaft (Vo 188/13-1 and SFB 249) is gratefully acknowledged.\r\n"
article_processing_charge: No
article_type: original
author:
- first_name: Michael
  full_name: Bräu, Michael
  last_name: Bräu
- first_name: Florian
  full_name: Dreyer, Florian
  last_name: Dreyer
- first_name: Peter M
  full_name: Jonas, Peter M
  id: 353C1B58-F248-11E8-B48F-1D18A9856A87
  last_name: Jonas
  orcid: 0000-0001-5001-4804
- first_name: Holger
  full_name: Repp, Holger
  last_name: Repp
- first_name: Werner
  full_name: Vogel, Werner
  last_name: Vogel
citation:
  ama: 'Bräu M, Dreyer F, Jonas PM, Repp H, Vogel W. A K+ channel in Xenopus nerve
    fibres selectively blocked by bee and snake toxins: binding and voltage-clamp
    experiments. <i>Journal of Physiology</i>. 1990;420:365-385. doi:<a href="https://doi.org/10.1113/jphysiol.1990.sp017918">10.1113/jphysiol.1990.sp017918</a>'
  apa: 'Bräu, M., Dreyer, F., Jonas, P. M., Repp, H., &#38; Vogel, W. (1990). A K+
    channel in Xenopus nerve fibres selectively blocked by bee and snake toxins: binding
    and voltage-clamp experiments. <i>Journal of Physiology</i>. Wiley-Blackwell.
    <a href="https://doi.org/10.1113/jphysiol.1990.sp017918">https://doi.org/10.1113/jphysiol.1990.sp017918</a>'
  chicago: 'Bräu, Michael, Florian Dreyer, Peter M Jonas, Holger Repp, and Werner
    Vogel. “A K+ Channel in Xenopus Nerve Fibres Selectively Blocked by Bee and Snake
    Toxins: Binding and Voltage-Clamp Experiments.” <i>Journal of Physiology</i>.
    Wiley-Blackwell, 1990. <a href="https://doi.org/10.1113/jphysiol.1990.sp017918">https://doi.org/10.1113/jphysiol.1990.sp017918</a>.'
  ieee: 'M. Bräu, F. Dreyer, P. M. Jonas, H. Repp, and W. Vogel, “A K+ channel in
    Xenopus nerve fibres selectively blocked by bee and snake toxins: binding and
    voltage-clamp experiments,” <i>Journal of Physiology</i>, vol. 420. Wiley-Blackwell,
    pp. 365–385, 1990.'
  ista: 'Bräu M, Dreyer F, Jonas PM, Repp H, Vogel W. 1990. A K+ channel in Xenopus
    nerve fibres selectively blocked by bee and snake toxins: binding and voltage-clamp
    experiments. Journal of Physiology. 420, 365–385.'
  mla: 'Bräu, Michael, et al. “A K+ Channel in Xenopus Nerve Fibres Selectively Blocked
    by Bee and Snake Toxins: Binding and Voltage-Clamp Experiments.” <i>Journal of
    Physiology</i>, vol. 420, Wiley-Blackwell, 1990, pp. 365–85, doi:<a href="https://doi.org/10.1113/jphysiol.1990.sp017918">10.1113/jphysiol.1990.sp017918</a>.'
  short: M. Bräu, F. Dreyer, P.M. Jonas, H. Repp, W. Vogel, Journal of Physiology
    420 (1990) 365–385.
date_created: 2018-12-11T12:03:29Z
date_published: 1990-01-01T00:00:00Z
date_updated: 2022-02-23T16:10:03Z
day: '01'
doi: 10.1113/jphysiol.1990.sp017918
extern: '1'
external_id:
  pmid:
  - '2324990'
intvolume: '       420'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1190055/
month: '01'
oa: 1
oa_version: None
page: 365 - 385
pmid: 1
publication: Journal of Physiology
publication_identifier:
  eissn:
  - 1469-7793
  issn:
  - 0022-3751
publication_status: published
publisher: Wiley-Blackwell
publist_id: '2920'
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'A K+ channel in Xenopus nerve fibres selectively blocked by bee and snake
  toxins: binding and voltage-clamp experiments'
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 420
year: '1990'
...