Brain extracellular potassium and genera anaesthetics

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Abstract
General anaesthetic agents (halothane, trichlorethylene, methohexital, pentobarbital, and alphaxalone–alphadolone) depress the extracellular accumulations (ΔEk) and associated focal potentials (ΔV) which are evoked in the cuneate nucleus by tetanic stimulation of peripheral nerves. Depressions of ΔV are significantly greater than those of ΔEk; at the same time there is a dissociation of the relation between ΔV and ΔEk. There are no detectable changes in the resting levels of K+ or the small voltage shifts evoked by low-frequency intranuclear stimulation with a microelectrode. When anaesthesia produces severe hypotension, augmentations of [K+]0 occur which can be attributed to depression of electrogenic Na–K pumping. A possible explanation of the reduction in K+ release resulting from afferent fibre activity would be failure of conduction caused by membrane stabilization or hyperpolarization.