Neuron Glia Signaling Pathways 101

4.1. Membrane Transport 102

4.1.1. Uptake of Radioactive Tracers 103

4.1.2. GABA and Glutamate Transporters 106

4.1.3. Localization of GABA Transporters 107

4.1.4. Localization of Glutamate Transporters 109

4.2. Electrophysiology of Membrane Transport 110

4.2.1. Glutamate Transport 111

4.2.2. Anion Conductance and Glutamate Transport 115

4.2.3. GABA Transport 116

4.3. Transmitter-operated Ion Channels 119

4.3.1. GABA Receptors 120

4.3.2. Glutamate Receptors 122

4.4. A Calcium-based Intercellular Signal Pathway 124

4.4.1. Ca2+ Waves in Retinal Glia 126

4.5. Nitric Oxide 127

4.5.1. General Features 128

4.5.2. Nitric Oxide in Retina 129

5. K+ Dynamics, Ion Channels, and Transretinal Potentials 135

5.1. Regulation of Extracellular Potassium 137

5.1.1. K+ Regulation in Retina 138

5.1.2. Directionality of Potassium Siphoning 141

5.2. Voltage-activated Ion Channels 143

5.2.1. Voltage-dependent Channels of Müller Cells 144

5.2.2. Inward-rectifying Potassium Channels 146

5.2.3. KIR Channels and K+Buffering Currents 148

5.3. Other Voltage-dependent Ion Channels 148

5.3.1. The Delayed Rectifier Channel (KDR) 149

5.3.3. Ca2+Channels and Ca2+-activated K+Channels 151

5.3.4. Sodium Channels 153

5.3.5. Chloride Channels 154

5.5. Why Voltage-dependent Ion Channels? 157

5.5.1. Spreading Depression 159

5.5.2. Spreading Depression Propagation in Retina 160

5.5.3. Translocation of Ion Channels 161

5.6. Light-evoked Changes in Extracellular K+ 162

5.7. Cellular Origins of the Electroretinogram 166

6. Role in Retinal Pathophysiology 181

6.1. Retinal Ischemia and Excitotoxicity 181

6.2. The Immune Response 186

6.3. Phagocytosis 190

6.4. Retinal Conditions with Potential Müller Cell Involvement 192

6.4.1. X-linked Juvenile Retinoschisis 192

6.4.2. Cystoid Macular Edema 193

6.4.3. Müller Cell Sheen Dystrophy 195

6.4.4. Retinal Detachment 197

6.4.5. Müller Cells in Retinal Membranes 197

6.5. Reactive Gliosis 198

6.5.1. Morphological Changes 200

6.5.2. Müller Cell Proliferation 201

6.5.3. Müller Cell Proliferation: Putative Mitogens 203

6.5.4. Cytokines-Growth Factors 204

6.5.5. Other Mitogens 206

6.5.6. Re-entry into Mitosis 207

6.5.7. Molecular Changes 209

6.5.8. GFAP-inductive Signal 211

6.5.9. GFAP Function 214

Appendix: On the Histology of the Retina 217

References 225

Index 273

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