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PMID: 2416920 Published · ppublish English Journal Article

A calcium-activated potassium current in motor nerve terminals of the mouse.

The Journal of physiology ·Vol. 368 ·1985-11-00 ·Pages 577-91

Mallart A

Abstract

Local circuit currents involving presynaptic terminals were recorded by micro-electrodes inserted into the perineurium of nerves from the triangularis sterni muscle of the mouse. A transient outward current component was isolated by blocking the voltage-activated (delayed rectifier) K current by 3,4-diaminopyridine (3,4-DAP). The amplitude of this component depended on external K concentration and fell to zero at [K]o = 15 mM. Since it also depended on [Ca]o, it was identified as a Ca-activated K current (IK(Ca)). Tetraethylammonium (TEA) (2 mM), Ba (2 mM), Co (10 mM) and Mn (2.5 mM) blocked IK(Ca). IK(Ca) decayed to zero in approximately 12 ms and recovered from inactivation in about 100 ms. Ca current was enhanced in inverse proportion to the degree of IK(Ca) depression. The possible role of IK(Ca) in the process of neuromuscular facilitation is briefly discussed.

MeSH Terms
4-Aminopyridine/analogs & derivatives Action Potentials/drug effects Amifampridine Aminopyridines/pharmacology Animals Barium/pharmacology Calcium/pharmacology Cobalt/pharmacology In Vitro Techniques Ion Channels/drug effects Manganese/pharmacology Mice Motor Endplate/physiology Neuromuscular Junction/physiology Potassium/physiology Synaptic Transmission Tetraethylammonium Tetraethylammonium Compounds/pharmacology
Chemicals
Aminopyridines Ion Channels Tetraethylammonium Compounds Barium Cobalt Manganese Tetraethylammonium 4-Aminopyridine Amifampridine Potassium Calcium
Authors & Affiliations
1 authors, click to expand affiliations / ORCID
Mallart A
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39 references, click to expand
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Article Info
Journal
The Journal of physiology
Abbr.
J Physiol
ISSN
0022-3751
DOI
10.1113/jphysiol.1985.sp015877
Published
1985-11-00
Pages
577-91
Language
English
Region
England
NLM ID
0266262
PMCID
PMC1192616
Subset
IM
External Links
PubMed source DOI: 10.1113/jphysiol.1985.sp015877 PMC Full Text View journal details
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