Dofetilide

The proximal tubular cell line HK-2 (human kidney 2, CRL-2190) of the normal adult human kidney was purchased from the American Type Culture Collection (ATCC). Cells were maintained in keratinocyte serum-free (KCSF) medium with 40 μg/mL bovine pituitary extract (Gibco BRL, Grand Island, NY, USA) and 5 ng/mL recombinant epidermal growth factor and incubated at 37℃ and 5% CO₂ in a humidified chamber. The cultured medium was replaced every 2–3 d for the cultured cells. A density of approximately 1 × 10⁵ HK-2 cells was seeded separately in each well of 96-well plates before treatment with test compounds and then maintained at 37℃ and 5% CO₂ in a humidified incubator for 1 d. All test chemicals, including dobutamine, dofetilide, citalopram, and ritodrine (MedChemExpress, Monmouth Junction, NJ, USA), were dissolved in dimethyl sulfoxide (DMSO) before the cell viability test.