Electrophysiology of rabbit Müller (glial) cells in experimental retinal detachment and PVR.
OBJECTIVE
To determine the electrophysiological properties of Müller (glial) cells from experimentally detached rabbit retinas.


METHODS
A stable local retinal detachment was induced by subretinal injection of a sodium hyaluronate solution. Müller cells were acutely dissociated and studied by the whole-cell voltage-clamp technique.


RESULTS
The cell membranes of Müller cells from normal retinas were dominated by a large inwardly rectifying potassium ion (K+) conductance that caused a low-input resistance (<100 M(Omega)) and a high resting membrane potential (-82 +/- 6 mV). During the first week after detachment, the Müller cells became reactive as shown by glial fibrillary acidic protein (GFAP) immunoreactivity, and their inward currents were markedly reduced, accompanied by an increased input resistance (>200 M(Omega)). After 3 weeks of detachment, the input resistance increased further (>300 M(Omega)), and some cells displayed significantly depolarized membrane potentials (mean -69 +/- 18 mV). When PVR developed (in 20% of the cases) the inward K+ currents were virtually completely eliminated. The input resistance increased dramatically (>1000 MOmega), and almost all cells displayed strongly depolarized membrane potentials (-44 +/- 16 mV).


CONCLUSIONS
Reactive Müller cells are characterized by a severe reduction of their K+ inward conductance, accompanied by depolarized membrane potentials. These changes must impair physiological glial functions, such as neurotransmitter recycling and K+ ion clearance. Furthermore, the open probability of certain types of voltage-dependent ion channels (e.g., Ca2+-dependent K+ maxi channels) increases that may be a precondition for Müller cell proliferation, particularly in PVR when a dramatic downregulation of both inward current density and resting membrane potential occurs.
Paul Flechsig Institute for Brain Research and the. Department of Ophthalmology, Eye Hospital, University of Leipzig, Germany.
M
M
Francke
F
F
Faude
T
T
Pannicke
A
A
Bringmann
P
P
Eckstein
W
W
Reichelt
P
P
Wiedemann
A
A
Reichenbach
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D004594:Electrophysiology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006821:Hyaluronoglucosaminidase / Q000633:toxicity; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009457:Neuroglia / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012160:Retina / Q000187:drug effects; D012163:Retinal Detachment / Q000139:chemically induced / Q000503:physiopathology*; D018630:Vitreoretinopathy, Proliferative / Q000139:chemically induced / Q000503:physiopathology
D005904:Glial Fibrillary Acidic Protein; D006821:Hyaluronoglucosaminidase; D011188:Potassium