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Electrophysiological properties of rat retinal Müller (glial) cells in postnatally developing and in pathologically
F Felmy1, T Pannicke, J A Richt
1Forschungsstelle für Experimentelle Ophthalmologie, Universitäts-Augenklinik Abt. II, Labor für Zellphysiologie und Molekularbiologie, Tübingen, Germany.
Abstract:
Retinal glial Müller cells are characterized by dominant K(+) conductances. The cells may undergo changes of their membrane currents during ontogeny and gliosis as described in rabbit and man. Although the rat retina is often used in physiological experiments, the electrophysiology of rat Müller cells is less well studied. The aim of the present study was to characterize their membrane currents in postnatal development and in two models of retinal degeneration. Freshly isolated cells were subjected to whole-cell patch clamp recordings. During the first 4 weeks after birth of rats, their Müller cells displayed an increase in all membrane currents, particularly in the inward currents elicited at hyperpolarizing potentials. The decrease of the membrane resistance from more than 760 MOmega to less than 50 MOmega was accompanied by a shift of the zero current potential from about -20 mV to -80 mV, similar as earlier observed in developing rabbit Müller cells. These developmental changes were found in pigmented Brown Norway rats as well as in rats with inherited retinal dystrophy (RCS rats). Moreover, an infection of Lewis rats with the Borna disease virus caused substantial neuroretinal degeneration but did not result in a strong reduction of inward currents and of the zero current potential of the Müller cells. Thus, rat Müller cells fail to change their basic membrane properties in two different models of retinal pathology. This is in contrast to human and rabbit Müller cells, which have been shown to undergo dramatic changes of their membrane physiology in response to retinal diseases and injuries.
Insights
Rat Müller cells (retinal glial cells) show developmental changes in membrane currents. Unlike rabbit and human cells, rat Müller cells do not significantly alter membrane properties during retinal degeneration.
Area of Science:
- Neuroscience
- Cell Physiology
- Retinal Biology
Background:
- Retinal Müller cells possess prominent K+ conductances.
- Müller cell membrane currents can change during development and gliosis in rabbits and humans.
- Rat retinal electrophysiology is less studied, particularly Müller cell membrane currents.
Purpose of the Study:
- To characterize rat Müller cell membrane currents during postnatal development.
- To investigate changes in rat Müller cell membrane currents in two models of retinal degeneration.
Main Methods:
- Whole-cell patch clamp recordings on freshly isolated rat Müller cells.
- Studies included postnatal development (first 4 weeks) and two retinal degeneration models (inherited retinal dystrophy and Borna disease virus infection).
Main Results:
- Rat Müller cells showed increased membrane currents, especially inward currents, during the first 4 weeks post-birth.
- Membrane resistance decreased, and zero current potential shifted significantly during development.
- These developmental changes occurred in both pigmented and dystrophic rats.
- Borna disease virus infection caused degeneration but minimal changes in Müller cell inward currents and zero current potential.
Conclusions:
- Rat Müller cells exhibit developmental changes in membrane currents similar to other species.
- Unlike human and rabbit Müller cells, rat Müller cells do not undergo significant membrane property alterations in response to the studied retinal pathologies.
- This suggests a species-specific difference in Müller cell response to retinal injury or disease.