The Effect of Nitric Oxide on Cultured Bovine Retinal Pigment Epithelial Cell

ABSTRACT

Nitric oxide (NO), a potencially toxic radical, is generally regarded as a multi-potent molecule to be implicated in a wide range of biological function. The presence of nitric oxide synthase(NOS) in the retina, the constitutive isoform in photoreceptor outer segments and and the inducible form in retinal pigment epithelial (RPE) cells, has been demonstrated. The effect of NO in retina has been studying mainly as neurotransmitter. Present study was undertaken to find the role of NO in cultured bovine retinal pigment epithelial cells. Cultured bovine retinal pigment epithelial cells were treated with various concentrations of NO generator, S-nitroso-N-acetyl-D, L-penicillamine (SNAP). The survival fractions were measured by MTT assay. The morphologic changes were observed with inverted phase contrast microscope and electron microscope. To evaluate the characteristics of cell death, cells were lysed for DNA extraction, and the agarose gel electrophoresis was done. NO brought a decrease in the survival fraction of cultured bovine retinal pigment epithelial cells as concentrations increased. At high concentrations, cells became sparse. Electron microscopic study showed destruction of nuclear membrane and chromatin condensation in 1 mM SNAP treated group. These findings were compatible with apoptotic cell death that was supported with DNA laddering pattern in agarose gel electrophoresis. NO can induce damage to retinal pigment epithelial cells, and damaged cells are destined to apoptotic cell death.