Potassium oxalate

A normal rat kidney epithelial cell line, NRK52E, was obtained from American Type Culture Collection (CTL-1571; Manassas, VA, USA). They were maintained as continuously growing monolayers (confluent condition) in 75 cm² Falcon T-flask (Fisher, Atlanta, GA, USA) in culture in 1:1 ratio Dulbecco’s modified essential medium nutrient mixture and F-12 (DMEM/F-12, Gibco BRL, Grand Island, NY, USA) containing 4 % fetal calf serum, 15 mmol/L HEPES, 20 mmol/L sodium bicarbonate, 0.5 mmol/L sodium pyruvate, 17.5 mmol/L glucose, streptomycin and penicillin at 37 °C in a 5 % CO₂ air atmosphere incubator. Under these conditions, cells achieved confluence, they were washed with serum and sodium pyruvate-free DMEM/F-12 media and incubated for 24 h, and then exposed to potassium oxalate (Sigma, St. Louis, USA) at a final concentration of 500 µmol/L or CaOx monohydrate (COM; 66.7 µg/cm²) Control cultures were untreated cells. The duration of cell exposure and concentration of COM crystals to which they were exposed was selected based on the results of our earlier studies [12 (link)].