Methotrexate induces cell swelling and necrosis in renal tubular cells

Background. The present study was carried Out to investigate if methotrexate (MTX) has a direct lethal effect in renal tubular Cells, and if SO, to further clarify the mechanisms of cell death. Materials and Methods. Renal tubular cells (LLC-PK1 cells) were incubated with MTX (0.01 mu M, 0.1 mu M, and 1 mu M), either alone or in combination with 0.1 mu M amiloride (Na+/H+ antiporter inhibitor) or 1 mu M carbachol (M-cholinergic agonist). Cell viability was then determined by means of trypan blue (TB) exclusion tests and MTT assays. Results. After 4 hr incubation with 0.1 mu M MTX the number of viable cells was decreased by 18% in comparison with control cells, and the proportion of dead cells was increased by 389%. Cell death induced by MTX was time-dependent and did riot show apoptotic features. On the contrary, cell swelling was discovered. This cell death was prevented by co-incubating the cells with amiloride or carbachol. Conclusions. MTX induces cell swelling and cell death in renal tubular LLC-PK1 cells. The tubular cell death induced by MTX is time-dependent. Cell death can be prevented by co-incubating with amiloride, thus indicating that the Na+/H+ antiporter and possibly other volume regulatory factors in renal tubular cells are involved in MTX-induced renal failure.