Diversity of Kir channel subunit mRNA expressed by retinal glial cells of the guinea-pig.
One of the main functions of Müller glial cells is the performance of retinal K+ homeostasis which is thought to be primarily mediated by K+ fluxes through inwardly rectifying K+ (Kir) channels expressed in Müller cell membranes. Until now, there is limited knowledge about the types of Kir channel subunits expressed by Müller cells. Using RT-PCR, we investigated the expression of mRNA encoding different Kir channel subunits in the retina of the guinea pig. In order to verify expression by Müller cells, primary cultures of guinea pig Müller cells were also investigated. Both retinae and cultured Müller cells express mRNA for a diversity of Kir channel subtypes which include members of at least four channel subfamilies: Kir2.1, Kir2.2, Kir2.4, Kir3.1, Kir 3.2, Kir4.1, Kir6.1, and Kir6.2. mRNAs for the following Kir channel subtypes were not detected in Müller cells: Kir1.1, Kir2.3, Kir3.3, Kir3.4, Kir4.2, and Kir5.1. It is concluded that the spatial buffering of extracellular K+ by Müller cells may be mediated by cooperation of different subtypes of Kir channels, and that the distinct Kir channel types involved in this function may change depending on the physiological or metabolic state of the retina.
Raap
Maik
M
Paul Flechsig Institute of Brain Research, Leipzig University, Jahnallee 59, D-04109 Leipzig, Germany.
Biedermann
Bernd
B
Braun
Peter
P
Milenkovic
Ivan
I
Skatchkov
Serguei N
SN
Bringmann
Andreas
A
Reichenbach
Andreas
A
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D005110:Extracellular Space / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006168:Guinea Pigs; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology
D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011188:Potassium