Light-induced changes of extracellular ions and volume in the isolated chick retina–pigment epithelium preparation
| Autor: | Roy H. Steinberg, Victor I. Govardovskii, H.N. Schwahn, A.V. Dmitriev |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Light
Physiology Sodium chemistry.chemical_element Calcium Retina chemistry.chemical_compound Chlorides Cations Extracellular medicine Animals Pigment Epithelium of Eye Tetramethylammonium Calcium metabolism Ion Transport Anatomy Sensory Systems Epithelium Quaternary Ammonium Compounds medicine.anatomical_structure chemistry Potassium Biophysics sense organs Extracellular Space Chickens Ion-Selective Electrodes Intracellular |
| Zdroj: | Visual Neuroscience. 16:1157-1167 |
| ISSN: | 1469-8714 0952-5238 |
| DOI: | 10.1017/s095252389916615x |
| Popis: | To better understand the mechanisms of extracellular space volume regulation and their possible effects on retinal function, light-induced changes in the concentrations of the principal extracellular ions (Na+, K+, Ca2+, and Cl−) were measured with ion-sensitive microelectrodes in the chick retina–pigment epithelium–choroid preparation. Changes of extracellular space volume were assessed by measuring the concentration of an impermeant marker, tetramethylammonium. In the inner retina, transient ON/OFF Na+ decrease was about twice as large as K+ increase, and the charge difference was compensated by a decrease in Cl− concentration. The ion changes were accompanied by extracellular space-volume decreases here. In the subretinal space, [Na+]o increase was about twice as large as K+ decrease, yet [Cl−]o also decreased; this was accompanied by a sustained extracellular space-volume increase. The ionic changes in the inner retina are consistent with a model of extracellular space-volume regulation which assumes that neuronal depolarization causes net uptake of NaCl, cell swelling, and extracellular space shrinkage. However, to prevent the apparent violation of electroneutrality in the subretinal space, our simple model should be expanded to include the involvement of unidentified anion(s). Substantial changes in the subretinal space volume may influence interaction between the neural retina and pigment epithelium. Among ionic changes, only the light-induced [K+]o decrease around the photoreceptors and the [Ca2+]o increase near the photoreceptor bodies and synaptic terminals are large enough (−25% and 7.5%, respectively) to be likely candidates for integrated intercellular signaling. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|