Purchase this article with an account.
D. Yang, B.A. Hughes; Molecular Diversity of Inwardly Rectifying Potassium Channels in Native Human Retinal Pigment Epithelium . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3451.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Inwardly rectifying K+(Kir) channels are abundantly expressed in the RPE apical membrane, where they function to establish the membrane potential and transport K+ into the subretinal space. Recently, we showed in bovine RPE that these channels are likely comprised of Kir7.1 channel subunits. Although native human RPE cells exhibit a Kir current consistent with Kir7.1, the subunit composition of the underlying channel(s) is presently unknown. The purpose of this study was to determine which Kir channel subunits are expressed in human RPE. Methods: Reverse transcription-polymerase chain reaction (RT-PCR) was performed for different Kir channel subunits using total RNA from freshly isolated human RPE sheets as well as neural retina. The identities of RT-PCR products from the RPE were confirmed by DNA sequencing. Results: RT-PCR analysis revealed transcripts for Kir1.1, Kir2.1, Kir2.2, Kir3.1, Kir 3.4, Kir4.2, Kir6.1, and Kir7.1 in the RPE. In neural retina, transcripts for Kir1.1, Kir2.1, Kir2.2, Kir2.3, Kir3.1, Kir3.2, Kir3.3, Kir3.4, Kir4.1, Kir4.2, Kir5.1, Kir6.1, Kir6. 2, and Kir7.1 were detected. Conclusions: As expected, human RPE expresses Kir7.1. In addition, human RPE also expresses members of five other Kir channel subfamilies that differ from each other in terms of rectification and regulation by intracellular factors such as ATP, pH, and G proteins. We conclude that multiple Kir channel subtypes may mediate the Kir conductance in human RPE and that the impact of individual Kir channel subtypes may change depending on the metabolic or physiologic condition of the cell.
This PDF is available to Subscribers Only