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Expression and polarized distribution of an inwardly rectifying K + channel, Kir4.1, in rat retinal pigment epithelium
Author(s) -
Kusaka Shunji,
Horio Yoshiyuki,
Fujita Akikazu,
Matsushita Kenji,
Inanobe Atsushi,
Gotow Takahiro,
Uchiyama Yasuo,
Tano Yasuo,
Kurachi Yoshihisa
Publication year - 1999
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1999.00373.x
Subject(s) - retinal pigment epithelium , pigment , chemistry , biophysics , retinal , biology , microbiology and biotechnology , anatomy , biochemistry , organic chemistry
1 In the eye, different substances and ions including potassium (K + ) are transported between neural retina and choroid via the subretinal space. Inwardly rectifying K + channels (Kir) on the apical membrane of retinal pigment epithelial (RPE) cells are thought to play an essential role in K + transport in the subretinal space. 2 Single‐channel recordings from the apical membrane of RPE cells exhibited functional expression of a Kir channel with properties identical to those of Kir4.1, while recordings from the basolateral membrane showed no detectable Kir channel currents. 3 The expression of Kir4.1 mRNA in RPE cells was confirmed by RT‐PCR analysis and in situ hybridization. Furthermore, using immunohistochemistry, we found that Kir4.1 was prominently expressed in RPE cells and localized specifically on the processes on their apical membrane. 4 Developmental studies revealed that expression of Kir4.1 started to appear 10 days or later after birth in RPE cells, in parallel with the maturation of retinal neuronal activity as represented by the a‐ and b‐waves of the electroretinogram. 5 These data suggest that Kir4.1 is one of the Kir channels involved in RPE‐mediated control of K + ions in the subretinal space.