| Title | Inhibition of UV-B induced apoptosis in corneal epithelial cells by potassium channel modulators. | | Author(s) | Ubels JL, Schotanus MP, Bardolph SL, Haarsma LD, Koetje LR, Louters JR | | Institution | Department of Biology, Calvin College, 3201 Burton St. SE, Grand Rapids, MI 49546, USA; Department of Ophthamology, Wayne State University School of Medicine, Detroit, MI 48201, USA. | | Source | Exp Eye Res 2009 Oct 26. | | Abstract | The goal of this study was to determine whether prevention of K(+) loss can protect human corneal-limbal epithelial (HCLE) cells from UV-B induced apoptosis. Immunostaining for activated caspase-3 of HCLE cells exposed to 150 - 200 mJ/cm(2) UV-B demonstrated induction of apoptosis 6 hrs after exposure. The number of apoptotic cells was decreased by incubation in medium with 25 or 100 mM K(+). If this protection is due to a reduction of UV induced K(+) loss then K(+) channel blockers should also protect HCLE cells from UV-B. Caspase-8 activity induced by exposure to UV-B at 150 mJ/cm(2) was significantly reduced when the cells were incubated in 0.3 muM BDS-I or 0.05-1 mM quinidine. Caspase-3 was also activated by UV-B and a reduction in activity was observed after incubation in 0.1-0.3 muM BDS-I and 0.1-1mM quinidine. Induction of DNA fragmentation, as measured by the TUNEL assay, was decreased by treatment with 0.3 muM BDS-I and 0.01-0.05 mM quinidine. Patch-clamp recording showed activation of K(+) channels after exposure to UV-B and a decrease in outward K(+) current was observed following application of BDS-I. Quinidine did not block K(+) currents in HCLE cells, suggesting that the protective effect of quinidine occurs by a mechanism other than via K(+) channels. The effect of the K(+) channel blocker BDS-1 on HCLE cells exposed to UV-B confirms that preventing K(+) efflux protects corneal epithelial cells from apoptosis. This suggests the elevated [K(+)] in tears may protect the corneal epithelium from effects of ambient UV-B. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19874821 |
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