[Changes in the concentration of extracellular potassium in the cerebral cortex with different parameters of electrical stimulation]

In anesthetized cats, a recording macroelectrode, a K+-sensitive microelectrode and a stimulating electrode were placed on the surface of the suprasylvian gyrus. As the duration or intensity of stimulus increased, the amplitude of K+-potential reflecting the changes in the extracellular concentration of K+ ions (delta [K+]o) was augmented, while the half time of decay decreased. delta [K+]o also increased when the number of stimuli increased. Repetitive tetanic stimulation resulted in impairment of the effect also in the case when [K+]o following the preceding stimulus, reached the initial level. K-potential started to decay in the course of prolonged tetanic stimulation; impairment of the neuronal activity is supposed to underlie this event.