In-vitro studies of aluminium-induced toxicity on kidney proximal tubular cells

The toxicity of aluminium (AI) to various cells is well described. However, little is known about its effect on kidney cells, which can be exposed to relatively high concentrations. In this study, the effect of aluminium as t he citrate complex in concentrations up to 100 muM/l was investigated using a monolayer cell culture of kidney proximal tubular cells (PTC). Aluminium was found to be slightly toxic; at 100 muM/l the PTCs lost viability by 15 , 20 and 24% after incubation for 24, 48 and 72 h, respectively. Viability was significantly reduced (P <0.001) after 48 h incubation with aluminium c oncentrations of 25, 50, 75 and 100 muM/l compared with controls. Lactate d ehydrogenase (LDH) release was significantly increased (P <0.001) with 100 muM/l Al to 44.67 +/- 1.76 and 50.33 +/- 0.88 compared with controls 24 +/- 1.00 and 28.33 2.34 U/l after 24 and 48 h incubation, respectively, indica ting damage to the plasma membrane. However, N-acetyl-beta -D-glucosaminida se (NAG) release in the medium of cells exposed to aluminium showed no diff erence from control values (P >0.1). Glucose consumption in aluminium-expos ed cells at 100 muM/l was slightly, but not significantly (P=0.14), increas ed during 48 h incubation. Electron micrographs of cells exposed to alumini um at 100 muM/l showed a slight reduction in microvilli density and the cel l tight junctions were not as clear compared with the control cells. Pretre atment with protective agents glutathione and tiopronin partly restored the viability of kidney proximal tubular cells to control values, whereas vita min C and/or cysteine, showed no effect. This study indicates that aluminiu m may show toxicity to kidney cells in culture. Several sites on the cell, i.e. microvilli, membrane and the cell junction, seem to be affected, howev er the mechanism(s) of damage remain unclear. (C) 2001 Elsevier Science B.V . All rights reserved.