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Louvenia D. Carter-Dawson, Yenabi J. Keflemariam, Laura J. Frishman, Ronald S. Harwerth; Localization of Potassium Channels Kir2.1 and Kir4.1 in Monkey Retina. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4132. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate distribution of Kir2.1 and Kir4.1 inwardly rectifying potassium channels in primate retina.
Posterior segments from monkey eyes were fixed in 4% paraformaldehyde in phosphate buffer. Retina samples were taken along the horizontal meridian of each eye. The sections were exposed to polyclonal antibody to Kir2.1 or Kir4.1 and monoclonal antibody to glutamine synthetase (GS), a marker for Müller cells. Antibody binding in retina was visualized with a Cy3 conjugated secondary antibody. Images of immunolabeled retina were captured by confocal microscopy and converted to 3D-projections using Image J software.
Kir4.1 was broadly expressed in Müller cells, in the somas in the inner nuclear layer (INL), processes and trunks in the inner plexiform layer, end-feet, and surrounding blood vessels. Kir2.1was predominately localized to bipolar cell dendrites, somas, axons and terminals. In several samples, Kir2.1 was detected in some neurons in the ganglion cell layer and neurons other than bipolar cells in the INL. GS co-localized with Kir4.1, but not with Kir2.1.
The distribution of Kir4.1 channels in monkey retina is consistent with reports for mouse and rat, thus indicating similar distributions across mammalian species. Kir2.1 distribution in monkey retina is similar to that reported for rat, except for prominent labeling of bipolar cell dendrites in monkey. Müller cells are reported to express Kir2.1 in mouse, but the lack of co-localization between GS and Kir2.1 indicates that these cells may not express Kir2.1 in monkey. Kir2.1 and Kir4.1 contribute to the generation of scotopic and photopic negative responses in the rat ERG. Since their distribution is similar in monkey, investigating alterations in their expression in glaucoma monkey retinas may provide insight into the changes in these negative ERG responses observed in monkeys with experimental glaucoma.
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