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Effects of Ba 2+ and tetraethylammonium on cortical neurones
Author(s) -
Krnjević K.,
Pumain R.,
Renaud L.
Publication year - 1971
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1971.sp009466
Subject(s) - tetraethylammonium , chemistry , cortical neurons , neuroscience , biophysics , potassium , biology , organic chemistry
1. Ba 2+ , applied by micro‐iontophoresis, excites most cortical neurones that are excitable by ACh; other neurones tend to be depressed. 2. The discharges evoked by Ba 2+ resemble those evoked by ACh, but they have an even slower time course and are characterized by firing in high frequency bursts. 3. The excitatory action of Ba 2+ , unlike that of ACh, is not abolished by muscarine antagonists; but it can be prevented with dinitrophenol. 4. The depolarizing effect of Ba 2+ is associated with a rise in membrane resistance and it has a reversal level 24 mV more negative than the resting potential. 5. These observations suggest that, as in other tissues, Ba 2+ reduced the K + conductance by a direct action on the cell membrane. Some diminution in Na + inactivation is indicated by the repetitive firing at high frequency. 6. TEA has a predominantly depressant effect on all neurones tested. Like Ba 2+ , it often increases greatly the duration of spikes, but there is no regular change in resting membrane resistance and no tendency to repetitive firing. TEA probably reduces only the delayed K + current. 7. Even in large doses neither Ba 2+ nor TEA interferes with the conductance increase that generates the typical prolonged IPSPs recorded in cortical neurones.