Presynaptic currents in frog motor endings

Membrane currents were recorded from non-myelinated frog endings by external electrodes. Changes in shape of the signals recorded at varying distances from the myelin end could be explained by assuming a non uniform distribution of Na and K channels along the presynaptic terminal. Specific channel b...

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Bibliographic Details
Published in:Pflügers Archiv 1984, Vol.400 (1), p.8-13
Main Author: MALLART, A
Format: Article
Language:English
Subjects:
4-Aminopyridine - analogs & derivatives
Action Potentials
Amifampridine
Aminopyridines - pharmacology
Animals
Biological and medical sciences
Electric Conductivity
Fundamental and applied biological sciences. Psychology
Ion Channels - drug effects
Motor Neurons - physiology
Nerve Endings - physiology
Peripheral nervous system. Autonomic nervous system. Neuromuscular transmission. Ganglionic transmission. Electric organ
Rana esculenta
Synapses - drug effects
Synapses - physiology
Tetraethylammonium
Tetraethylammonium Compounds - pharmacology
Tetrodotoxin - pharmacology
Vertebrates: nervous system and sense organs
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Summary:Membrane currents were recorded from non-myelinated frog endings by external electrodes. Changes in shape of the signals recorded at varying distances from the myelin end could be explained by assuming a non uniform distribution of Na and K channels along the presynaptic terminal. Specific channel blocking agents revealed that Na channels are present in highest density in the first half of each terminal branch and at almost undetectable levels near the extreme end, while K channels show a more widespread distribution with higher density at medial parts. Suppression of K conductance revealed Ca current which was seen as outward current near the myelin end.
ISSN:0031-6768
1432-2013
DOI:10.1007/BF00670529