gms | German Medical Science

102. Jahrestagung der DOG

Deutsche Ophthalmologische Gesellschaft e. V.

23. bis 26.09.2004, Berlin

L-type Ca2+ channels in the retinal pigment epithelium: differences in the expression pattern between ARPE-19 cells and RPE cells from patients with choroidal neovascularization

Meeting Abstract

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  • corresponding author S. Wimmers - Experimentelle Ophthalmologie, Universitätsklinikum Hamburg-Eppendorf
  • L. Coeppicus - Experimentelle Ophthalmologie, Universitätsklinikum Hamburg-Eppendorf
  • S. Ehmer - Experimentelle Ophthalmologie, Universitätsklinikum Hamburg-Eppendorf
  • O. Strauß - Experimentelle Ophthalmologie, Universitätsklinikum Hamburg-Eppendorf

Evidenzbasierte Medizin - Anspruch und Wirklichkeit. 102. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft. Berlin, 23.-26.09.2004. Düsseldorf, Köln: German Medical Science; 2004. Doc04dogP 126

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Veröffentlicht: 22. September 2004

© 2004 Wimmers et al.
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Secretion of various growth factors by the retinal pigment epithelium (RPE) is substantial for normal structure of the retina but also plays a role in the etiology of retinal diseases. Further, the RPE itself is the target of cytokines. L-type Ca2+ channels are mediating intracellular processing from incoming signals and subsequent growth factor secretion. Purpose of this study was to resolve the molecular structure of the Ca2+ channels expressed by the RPE and to compare it to those of patients with choroidal neovascularization (CNV).


The biophysical properties of Ca2+ currents in the RPE were investigated by the patch-clamp technique. The complete coding sequence of the pore forming α subunit of the human RPE cell line ARPE-19 and from patients with CNV was cloned and the expression pattern of accessory subunits was investigated by RT-PCR.


The RPE from patients with CNV show Ba2+ currents similar to the Ba2+ currents in ARPE-19 cells. Both were reduced by the specific inhibitor nifedipine and stimulated by BayK 8644. The currents displayed unusual fast inactivation kinetics. We found differences between ARPE-19 cells and CNV in the pore forming α subunit Cav1.3 as well as in the expression pattern of the accessory Ca2+ channel subunits.


The Ba2+ currents we found in RPE cells displayed dihydropyridine sensitivities like neuroendocrine Ca2+ channels. Consistently, we revealed the splice-variant of the Cav1.3 α subunit expressed in the RPE. The obvious differences in the inactivation kinetics between neuroendocrine Ca2+ channels in the RPE and other cells may be explained by a yet unknown regulation mechanism of the channels in the RPE. These differences may be caused by the expression of the splicing variant and the expression pattern of accessory subunits.