1 Introduction.- 2 Ion-Selective Microelectrodes.- 3 K+ Homeostasis in the ECS.- 3.1 Stability of K+ in the Extracellular Fluid.- 3.2 Sources of [K+]e Increases.- 3.3 Redistribution of Extracellularly Accumulated K+.- 3.3.1 Role of Active Transport.- 3.3.2 Role of Glial Cells in K+ Homeostasis.- 3.3.2.1 The Spatial Buffer Mechanism.- 3.3.2.2 Active K+ Transport.- 3.3.2.3 Channel-Mediated KCl Uptake.- 3.3.3 K+ Diffusion in the ECS.- 3.3.4 K+ Exchange Between Extracellular Fluid and Blood.- 4 Dynamic [K+]e Changes.- 4.1 Dynamic [K+]e Changes in the Spinal Cord...- 4.1.1 [K+]e Changes Induced by Electrical Stimulation of Peripheral Nerves.- 4.1.2 Depth Profile of [K+]e Changes in the Spinal Cord.- 4.1.3 Electrical Stimulation of Descending Pathways.- 4.1.4 [K+]e Changes Induced by Adequate Stimulation.- 4.1.4.1 Acute Nociceptive and Non-Nociceptive Stimuli.- 4.1.4.2 Chronic Nociceptive Stimuli.- 4.1.5 [K+]e Changes Associated with Spontaneous Activity in the Dorsal Horns of the Spinal Cord.- 4.1.6 [K+]e Changes Induced by Systemic Administration of Drugs, Transmitters, and Neuropeptides.- 4.2 Dynamic [K+]e Changes in the Brain.- 4.2.1 Dynamic [K+]e Changes in the Cerebral Cortex and Striatum.- 4.2.2 Dynamic [K+]e Changes in the Mesencephalic Reticular Formation.- 4.2.3 Dynamic [K+]e Changes in the Cerebellum and Hippocampus.- 4.3 Functional Significance of [K+]e Changes in the CNS.- 4.3.1 Role of K+ in Presynaptic Inhibition.- 4.3.1.1 Depolarization of Primary Afferents.- 4.3.1.2 Effect of Picrotoxin and Bicuculline.- 4.3.2 Effect of K+ Accumulation on Synaptic Transmission.- 4.3.2.1 Effect of K+ on Neuronal Membrane Potential.- 4.3.2.2 Effect of K+ on Synaptic Potentials and Spontaneous Activity.- 4.3.2.3 Effect of K+ on Flexor Reflex.- 4.3.3 K+ Accumulation and Glial Cell Function.- 4.3.4 K+ Accumulation and the Therapeutic Effect of Electrostimulation.- 4.3.5 Other Functional Correlates of a [K+]e Increase.- 4.3.6 K+ Accumulation and Its Functional Significance in Pathological Processes.- 4.3.6.1 [K+]e Changes During Ischaemia and Hypoxia.- 4.3.6.2 K+, Epilepsy, and Epileptiform Activity.- 4.3.6.3 [K+]e and Spreading Depression.- 4.4 Dynamic K+ Changes in the Organ of Corti.- 4.4.1 Resting K+ Concentration in the Inner Ear.- 4.4.2 Dynamic Changes in K+ Concentration in the Organ of Corti Evoked by Acoustic Stimuli.- 4.4.3 Functional Significance of Dynamic [K+]e Changes in the Organ of Corti.- 4.5 Changes in K+ Concentration in the Retina.- 4.5.1 Regulation of [K+]e by Glial Cells in the Retina.- 5 Dynamic Changes in Extracellular Na+, Cl-, and Ca2+ Concentration.- 5.1 Changes Induced in Resting [Ca2+]e During Stimulation of Afferent Input.- 5.2 [Ca2+]e Changes in Pathological States.- 5.3 Functional Significance of Dynamic [Ca2+]e Changes.- 6 Dynamic pHe Changes.- 6.1 Extracellular Buffering Power.- 6.2 Activity-Related Dynamic pHe Changes in Nervous Tissue.- 6.2.1 Resting pHe.- 6.2.2 pHe Changes Evoked by Stimulation of Afferent Input.- 6.2.2.1 pHe Changes Evoked by Adequate Stimulation of Skin Nociceptors.- 6.2.3 Effect of Block of Synaptic Transmission on pHe Changes.- 6.2.4 pHe Changes Induced by K+ Depolarization.- 6.3 Mechanisms of pHe Changes in the CNS.- 6.3.1 Effect of Sodium Fluoride.- 6.2.3 Effect of Ouabain.- 6.3.3 Effect of Amiloride.- 6.3.4 Effect of SITS and DIDS.- 6.3.5 Effect of Acetazolamide.- 6.3.6 Effect of Furosemide.- 6.3.7 Effect of Block of H+ Channels.- 6.4 Role of Glial Cells in pHe Homeostasis.- 6.5 pHe Changes in the Retina.- 6.6 pHe Changes During Anoxia, Ischaemia, Epilepsy, and SD.- 6.7 Functional Significance of pHe Changes.- 7 Dynamic Changes in Size of the ECS.- 7.1 Measurement of Changes in Size of the ECS by Means of K+-ISMs.- 7.2 Changes Induced in Size of the ECS by Electrical Stimulation.- 7.3 Changes Induced in Size of the ECS by Adequate Stimulation.- 7.4 Mechanisms of Dynamic Changes in Size of the ECS.- 7.4.1 Volume Changes Induced by Changes in Extracellular Osmolarity.- 7.4.2 Volume Changes During Neuronal Activity.- 7.4.3 Transport Systems of Glial Cells and Regulation of Their Volume.- 7.4.4 Changes in Cell Volume Induced by Inhibition of Na+/K+ ATPase.- 7.5 Functional Significance of Dynamic Volume Changes in the Microenvironment of Nerve Cells.- 8 Conclusion.- References.
