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Outwardly rectifying K+ channels display clustering in guinea pig retinal Müller cells
T Pannicke1, A Reichenbach, W Reichelt
1Department of Neurophysiology, Paul-Flechsig-lnstitute for Brain Research, University of Leipzig, Germany. pant@server3.medizin.uni-leipzig.de
Abstract:
The cell-attached configuration of the patch-clamp technique was used to characterize the outward currents in acutely isolated Müller cells from the guinea pig retina. Sixty-five of 353 patches displayed macroscopic, outwardly rectifying currents due to depolarizing voltage steps. Single channel transitions were found in only two patches. The remaining patches did not reveal any voltage-dependent currents. Tail current analysis revealed a reversal potential close to the resting membrane potential. The currents disappeared if internal K+ was replaced by Cs+ in inside-out patches. From these results we conclude that guinea pig Müller cells possess voltage-dependent K+ channels that are distributed in clusters.
Insights
Guinea pig Müller cells possess voltage-dependent potassium channels. These channels, identified using patch-clamp electrophysiology, appear to be clustered in the retina.
Area of Science:
- Neuroscience
- Retinal Physiology
- Cellular Electrophysiology
Background:
- Müller cells are essential glial cells in the vertebrate retina.
- Their electrophysiological properties are crucial for retinal function and homeostasis.
- Understanding ion channel activity in Müller cells is key to retinal research.
Purpose of the Study:
- To characterize outward currents in guinea pig retinal Müller cells.
- To identify the presence and properties of voltage-dependent ion channels.
- To investigate the distribution of these channels.
Main Methods:
- Utilized the cell-attached patch-clamp technique on acutely isolated guinea pig Müller cells.
- Applied depolarizing voltage steps to evoke and analyze membrane currents.
- Performed tail current analysis and ion substitution experiments (K+ with Cs+) in inside-out patches.
Main Results:
- Outwardly rectifying currents were observed in 65 out of 353 patches upon depolarization.
- Single channel activity was rarely detected; most patches showed macroscopic currents.
- Tail current reversal potentials approximated the resting membrane potential.
- Observed currents were abolished by internal potassium ion (K+) replacement with cesium (Cs+).
Conclusions:
- Guinea pig Müller cells express voltage-dependent potassium channels.
- These potassium channels are likely distributed in clusters within the Müller cell membrane.
- The findings contribute to understanding Müller cell function and retinal ion transport.