The effect of sertraline, a selective serotonin reuptake inhibitor (SSRI), on cytosolic free Ca^(2+) concentrations ([Ca^(2+)]i) in a rabbit corneal epithelial cell line (SIRC) is unclear. This study explored whether sertraline changed basal [Ca^(2+)]i levels in suspended SIRC cells by using fura-2 as a Ca^(2+)-sensitive fluorescent dye. Sertraline at concentrations between 10-100 μM increased [Ca^(2+)]i in a concentrationdependent manner. The Ca^(2+) signal was reduced by 23% by removing extracellular Ca^(2+). Sertraline induced Mn^(2+) influx, leading to quench of fura-2 fluorescence, suggesting Ca^(2+) influx. This Ca^(2+) influx was inhibited by phospholipase A_2 inhibitor aristolochic acid, but not by store-operated Ca^(2+) channel blockers and protein kinase C/A modulators. In Ca^(2+)-free medium, pretreatment with the endoplasmic reticulum Ca^(2+) pump inhibitor thapsigargin, cyclopiazonic acid or 2,5-di-tert-butylhydroquinone greatly inhibited sertraline-induced Ca^(2+) release. Inhibition of phospholipase C with U73122 abolished sertralineinduced [Ca^(2+)]i rise. At concentrations of 5-50 μM, sertraline killed cells in a concentration-dependent manner. The cytotoxic effect of 25 μM sertraline was not reversed by prechelating cytosolic Ca^(2+) with BAPTA/AM. Collectively, in SIRC cells, sertraline induced [Ca^(2+)]i rises by causing phospholipase Cdependent Ca^(2+) release from the endoplasmic reticulum and Ca^(2+) influx via phospholipase A_2-sensitive Ca^(2+) channels. Sertraline-caused cytotoxicity was mediated by Ca^(2+)-independent pathways.
