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PMID: 6276548 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

Effects of divalent cations on toad end-plate channels.

The Journal of membrane biology ·Vol. 64 ·No. 1-2 ·1982-00-00 ·Pages 55-66

Takeda K, Gage PW, Barry PH

Abstract

Miniature end-plate currents (MEPCs) and acetylcholine-induced current fluctuations were recorded in voltage-clamped, glycerol-treated toad sartorius muscle fibers in control solution and in solutions with added divalent cations. In isosmotic solutions containing 20 mM Ca or Mg, MEPCs had time constants of decay (tau D) which were about 30% slower than normal. In isotonic Ca solutions (Na-free), greater increases in both tau D and channel lifetime were seen; the null potential was -34 mV, and single-channel conductance decreased to approximately 5 pS. Zn or Ni, at concentrations of 0.1-5 mM, were much more effective in increasing tau D than Ca or Mg, although they did not greatly affect channel conductance. The normal temperature and voltage sensitivity of tau was not significantly altered by any of the added divalent cations. Surface potential shifts arising from screening of membrane fixed charge by divalent cations cannot entirely explain the observed increases in tau, especially when taken together with changes in channel conductance.

MeSH Terms
Acetylcholine/pharmacology Animals Bufo marinus Calcium/pharmacology Ion Channels/drug effects,physiology Kinetics Magnesium/pharmacology Membrane Potentials/drug effects Motor Endplate/drug effects,physiology Neostigmine/pharmacology Neuromuscular Junction/physiology Temperature
Chemicals
Ion Channels Neostigmine Magnesium Acetylcholine Calcium
Authors & Affiliations
3 authors, click to expand affiliations / ORCID
Takeda K
Gage P W
Barry P H
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41 references, click to expand
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Article Info
Journal
The Journal of membrane biology
Abbr.
J Membr Biol
ISSN
0022-2631
DOI
10.1007/BF01870768
Published
1982-00-00
Pages
55-66
Language
English
Region
United States
NLM ID
0211301
Subset
IM
External Links
PubMed source DOI: 10.1007/BF01870768 View journal details
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