Summary
In cats under pentobarbitone anaesthesia, GABA was tested on cortical, pericruciate neurones and its action compared with IPSPs evoked by surface stimulation. GABA was applied to individual cells by microiontophoresis, while recording the membrane potential and resistance. When K citrate-recording electrodes were used, GABA always hyperpolarized the cell and lowered its resistance, like the synaptic inhibitory effect. By adequate polarization both the action of GABA and the IPSP could be reversed, at a similar level of membrane potential. Both could also be reversed by injecting Cl− into a cell from a KCl recording electrode and the new reversal potentials also did not differ significantly from each other: after this treatment, some cells could be excited with GABA. All these effects of GABA were only seen when it was applied outside the neurones; intracellular injections were ineffective. Since the reversal potentials for the action of GABA and the IPSP are approximately similar, it is concluded that GABA could be the main cortical inhibitory transmitter.
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Krnjević, K., Schwartz, S. The action of γ-Aminobutyric acid on cortical neurones. Exp Brain Res 3, 320–336 (1967). https://doi.org/10.1007/BF00237558
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DOI: https://doi.org/10.1007/BF00237558