Effects Produced on Inhibitory Postsynaptic Potentials by the Coupled Injections of Cations and Anions into Motoneurons

Ions have been injected into cat motoneurons impaled by a double microelectrode. Current has been passed down one barrel and up the other, so injecting cations out of the former and anions out of the latter. The injection of (K+ + Cl-) ions gave a depolarizing shift of the EIPSP almost as large as f...

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Bibliographic Details
Published in:Proceedings of the Royal Society of London. Series B, Biological sciences Biological sciences, 1964-05, Vol.160 (979), p.197-210
Main Authors: Eccles, John Carew, Eccles, Rosamond M., Ito, M.
Format: Article
Language:English
Subjects:
Anions
Cations
Cats
Cell membranes
Chlorides
Chlorine
Electric current
Electrodes
Electrophysiology
Extracellular Space
Histocytochemistry
Inhibitory Postsynaptic Potentials
Injections
Ion currents
Ion Exchange
Ion injection
Ions
Membrane potential
Motor Neurons
Neurons
Permeability
Potassium
Pumps
Sodium
Time constants
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Summary:Ions have been injected into cat motoneurons impaled by a double microelectrode. Current has been passed down one barrel and up the other, so injecting cations out of the former and anions out of the latter. The injection of (K+ + Cl-) ions gave a depolarizing shift of the EIPSP almost as large as for a Cl- ion injection, and with a time course comparable with that for injections of Cl- or K+ ions alone. The injection of (Na+ + Cl-) ions displaced the EIPSP by much the same amount and again the recovery time was almost as fast as after a Cl- ion injection, and much faster than after the injection of Na+ ions alone. On the other hand injection of (2Na+ + SO24- ions caused a slight displacement of the EIPSP in the hyperpolarizing direction. It was postulated that, when (K+)i is depleted, there is an accelerated operation of an inward pump for (K+ + Cl-) ions with the consequence that the decline of high (Cl-)i is slowed by a factor of three or more. The ion injection procedures did not provide evidence for or against the participation of K+ ion movements in the generation of the IPSP, but this participation at a level comparable with that of Cl- ions had to be postulated in order to account for the normal hyperpolarizing character of the IPSP.
ISSN:0962-8452
0080-4649
0950-1193
1471-2954
2053-9193
DOI:10.1098/rspb.1964.0036