Cytotoxic effect of spermine on retinal pigment epithelial cells.

Purpose: A prior study showed inactivation of ornithine-delta-aminotransferase (OAT)-deficient human retinal pigment epithelial (RPE) cells by a specific irreversible inhibitor (5-fluoromethylornithine; 5-FMO) leading to cell death, in an in vitro model of gyrate atrophy (GA) of the choroid and retina. In the present study, the cytotoxicity of metabolites of ornithine, especially spermine, in RPE cells was investigated, to clarify the mechanism of ornithine cytotoxicity in RPE cells.

Methods: RPE cells were incubated with ornithine or compounds involved in ornithine metabolic pathways.

Prevention of ornithine cytotoxicity by nonpolar side chain amino acids in retinal pigment epithelial cells.

Purpose: To investigate the effect of amino acids on ornithine cytotoxicity in ornithine-delta-aminotransferase (OAT)-deficient human retinal pigment epithelial (RPE) cells as an in vitro model of gyrate atrophy (GA) of the choroid and retina.

Methods: RPE cells were treated with 0.5 mM 5-fluoromethylornithine (5-FMOrn), a specific and irreversible OAT inhibitor.