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Role of glial K(+) channels in ontogeny and gliosis: a hypothesis based upon studies on Müller cells
- Source :
- Glia. 29(1)
- Publication Year :
- 1999
-
Abstract
- The electrophysiological properties of Müller cells, the principal glial cells of the retina, are determined by several types of K(+) conductances. Both the absolute and the relative activities of the individual types of K(+) channels undergo important changes in the course of ontogenetic development and during gliosis. Although immature Müller cells express inwardly rectifying K(+) (K(IR)) currents at a very low density, the membrane of normal mature Müller cells is predominated by the K(IR) conductance. The K(IR) channels mediate spatial buffering K(+) currents and maintain a stable hyperpolarized membrane potential necessary for various glial-neuronal interactions. During "conservative" (i.e., non-proliferative) reactive gliosis, the K(IR) conductance of Müller cells is moderately reduced and the cell membrane is slightly depolarized; however, when gliotic Müller cells become proliferative, their K(IR) conductances are dramatically down-regulated; this is accompanied by an increased activity of Ca(2+)-activated K(+) channels and by a conspicuous unstability of their membrane potential. The resultant variations of the membrane potential may increase the activity of depolarization-activated K(+), Na(+) and Ca(2+) channels. It is concluded that in respect to their K(+) current pattern, mature Müller cells pass through a process of dedifferentiation before proliferative activity is initiated.
Details
- ISSN :
- 08941491
- Volume :
- 29
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Glia
- Accession number :
- edsair.pmid..........e6e71c342bb67c21b27b22bbbacd3fe2