Purpose. To evaluate the effects of ultraviolet B light (UV-B on mitochondrial inner membrane function, cell viability, and migration of cultured human corneal epithelial cells. Methods. After UV-B exposure in SV- 40 transfected human corneal epithelial cells (T-HCEC), mitochondrial function was assessed by digital microfluorography using the mitochondrial marker, rhodamine 123 (Rh 123). The oxygen consumption rate of T-HCEC suspensions (107 cells/ml) was measured by an O2 meter, and adenosine triphosphate contents were measured by luciferase chemiluminescence. Cell viability and migration was observed by propidium iodide (PI) staining and migration assays. Results. UV-B exposure caused an immediate drop in O2 consumption by T-HCEC suspensions, whereas exposure of a monolayer culture of T-HCEC to UV-B at radiant exposures of 50 mJ/cm2 caused a reversible decrease in Rh 123 fluorescence (22.4%) and a significant decrease in adenosine triphosphate contents (1.52 ± 0.05 nmol/106 cells) compared to control (2.93 ± 0.12 nm/106 cells) after 10 minutes. The effects of Rh 123 fluorescence were irreversible at 100 mJ/cm2, which approximately corresponded with the threshold dose at which cells positive to PI staining (PI+) appeared. UV-B doses of 50 mJ/cm2 caused detachment of T-HCEC, primarily PI-, whereas higher doses (100 mJ/cm2) resulted in PI+ cells that did not detach from the dish. These PI+ cells hindered the migration of surrounding viable cells; detachment of PI- cells allowed cells to migrate and to cover a trough created by a 500 μm wide beam of UV-B. Conclusions. Threshold levels of UV-B (100 mJ/cm2) are associated with irreversible mitochondrial dysfunction and with the loss of the ability for cultured corneal epithelial cells to detach in vitro.
|ジャーナル||Investigative Ophthalmology and Visual Science|
|出版ステータス||Published - 1997 4 11|
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