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

  • 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

The electronic version of this article is the complete one and can be found online at:

Published: September 22, 2004

© 2004 Wimmers et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.




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.