Effect of sertraline on Ca ²⁺ fluxes in rabbit corneal epithelial cells

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 Ca2+ influx via phospholipase A ₂ -sensitive Ca ²⁺ channels. Sertraline-caused cytotoxicity was mediated by Ca ²⁺ -independent pathways.