Purchase this article with an account.
O. Zeitz, L. Schlichting, O. Strauss; Hydroxyl Radical Induced [Ca2+]I Increase Is Mediated by the Reverse Mode of NCX1 in Retinal Pigment Epithelium. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2010. doi: https://doi.org/.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
An increased oxidative exposure of the retinal pigment epithelium (RPE) is hypothesized to play an important role in the genesis of age-related macular degeneration (ARMD). Oxidative cell damage might be mediated by a disturbance of the Ca2+-homeostasis, which leads to functional changes and apoptosis. In the present study, the reverse mode of the NCX1 is studies as a potential Ca2+ entry route after hydroxyl radical (OH- ) stimulation.
All experiments were performed using the human RPE cell line ARPE-19. The intracellular Ca2+-content was determined by implementing the Fura-2 method. The cells were exposed for 5 minutes with OH- twice with an interval of 1h between. OH- radicals were created via the Fenton reaction using H2O2 and Fe3+. One of both OH- exposures was done in presence and one in absence of KB-R7943, which blocks the reverse mode of the NCX1, or nifedipine, a L-type Ca2+ channel blocker. For control purposes the cells were exposed twice to OH- without adding any pharmacological compound (sham control).
: Immediately after the onset of radical exposure the ARPE-19 cells showed a steep transient Ca2+-peak. The amplitude of this Ca2+-increase is significantly reduced in the presence of KB-R7943, while in the nifedipine and the sham control group the second Ca2+-peak amplitude is not reduced but even slightly increased (for quantitative results please refer to the table).
Oxidative exposure of cultured RPE cells leads to a transient increased intracellular Ca2+ load. This increase is mediated by the reverse mode of the NCX1. This might be a potential target for future therapy since oxidative stress is thought to be one of the major risk factors for ARMD and disturbed Ca2+ handling might lead to various cellular dysfunctions. The latter may include altered phagocytosis activity as well as changes in gene expression pattern and apoptosis.
This PDF is available to Subscribers Only