[Non-synaptic inhibition in the cortex of the cat]

Experiments were carried out on cats under pentobarbital anaesthesia. Two stimulating electrodes (S1 and S2), a recording macroelectrode and K+-selective microelectrode were placed on g. suprasylvius. A strong stimulus applied through S1 elicited slow negativity (SN) and increase in [K+]o. At that time the dendritic potential (DP) evoked by stimulation through S2 was depressed. The depression of DP correlated with the voltage of SN and with the level of [K+]o. It is suggested that DP depression is caused by presynaptic action of K+ ions.