Effect of celecoxib on Ca²⁺ fluxes and proliferation in MDCK renal tubular cells

The effect of celecoxib on renal tubular cells is largely unexplored. In Madin Darby canine kidney (MDCK) cells, the effect of celecoxib on intracellular Ca²⁺ concentration ([Ca²⁺]_i) and proliferation was examined by using the Ca²⁺-sensitive fluorescent dye fura-2 and the viability detecting fluorescent dye tetrazolium, respectively. Celecoxib (≥1 μM) caused an increase of [Ca²⁺]_i in a concentration-dependent manner. Celecoxib-induced [Ca²⁺]_i increase was partly reduced by removal of extracellular Ca²⁺. Celecoxib-induced Ca²⁺ influx was independently suggested by Mn ²⁺ influx-induced fura-2 fluorescence quench. In Ca²⁺-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca ²⁺-ATPase, caused a monophasic [Ca²⁺]_i increase, after which celecoxib only induced a tiny [Ca²⁺] _iincrease; conversely, pre-treatment with celecoxib completely inhibited thapsigargin-induced [Ca²⁺]_i increases. U73122, an inhibitor of phospholipase C, abolished ATP (but not celecoxib)-induced [Ca²⁺]_i increases. Overnight incubation with 1 or 10 μM celecoxib decreased cell viability by 80% and 100%, respectively. These data indicate that celecoxib evokes a [Ca²⁺]_i increase in renal tubular cells by stimulating both extracellular Ca²⁺ influx and intracellular Ca²⁺ release and is highly toxic to renal tubular cells in vitro.