The potassium channel Kv4.2 is expressed in subtypes of retinal ganglion cells
Abstract
Fast transient potassium currents (IA ) contribute to neuronal plasticity by regulating action potential generation and signal processing in dendrites. Kv4.2 channels generate transient potassium currents. Kv4.2 is expressed in the somas of some retinal ganglion cells (RGCs) and in two bands in the inner plexiform layer (IPL). This suggests expression in functional subtypes of RGCs. We characterized which RGC subtypes express Kv4.2; and IA in RGCs that express or do not express Kv4.2. Kv4.2 and melanopsin expression were assayed with immunohistochemistry. RGC morphology was determined using transgenic mice in which some RGCs are filled with yellow fluorescent protein (YFP), or by filling RGCs with Alexa dye via patch pipette after recording potassium currents. Three morphological RGC subtypes with predominantly Kv4.2-positive cells were identified: intrinsically-photosensitive RGCs (ipRGCs), a subtype with small dendritic field sizes and highly branched dendrites, and a previously unidentified subtype with sparse and thin dendrites. Occasional Kv4.2-positive RGCs occurred in subtypes with predominantly Kv4.2-negative RGCs. RGCs with somatic Kv4.2 expression also expressed Kv4.2 in the dendrites. The expression of Kv4.2 in ipRGCs was further confirmed by co-expression with melanopsin, a photopigment specific to ipRGCs. Of the RGCs in which I A was assayed, all of the RGCs that expressed Kv4.2 also had I A . None of the RGCs that lacked IA expressed Kv4.2. Some RGCs without Kv4.2 did have IA .
Recommended Citation
Lin Chen,
"The potassium channel Kv4.2 is expressed in subtypes of retinal ganglion cells"
(January 1, 2009).
ETD Collection for Wayne State University.
Paper AAI1464953.
http://digitalcommons.wayne.edu/dissertations/AAI1464953
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