Effect of medium pH on the cytotoxicity of hydrophilic statins

Purpose. The aim of this study was to examine the mechanism of pravastatin- and rosuvastatin-induced cytotoxicity and the relationship between pravastatin- and rosuvastatin-induced cytotoxicity and medium pH using human prototypic embryonal rhabdomyosarcoma cell line (RD) and rat myoblast cell line (L6) as a model of in vitro skeletal muscle. Methods. Statin-induced reduction of cell viability and apoptosis was measured by 3-(4,5-dimethylthiazol-2-yl)2,5 -diphenyl tetrazolium bromide (MTT) assay and caspase assay. Intracellular accumulation of statins was determined using an HPLC system. Results. Rosuvastatin cytotoxicity, reduction of cell viability, morphological changes and caspase activation at acidic pH (pH 6.8) were significantly greater than those at neutral pH (pH 7.4). Rosuvastatin accumulation at acidic pH was greater than that at pH 7.4. On the other hand, medium pH had no effect on pravastatin accumulation. Conclusions. Rosuvastatin cytotoxicity at acidic pH is associated with increasing intracellular accumulation of rosuvastatin. On the other hand, medium pH had no effect on cytotoxicity of pravastatin.