Influence of cadmium speciation for the evaluation of in vitro cadmium toxicity on LLC-PK1 cells

The main objective of the present work was to assess the potentiality of in vitro models to improve our understanding of cadmium-induced toxicity, especially on epithelial renal cells. Indeed cadmium, a potent toxic metal, poses a serious environmental threat and the mechanisms of its renal toxicity need to be clarified. Cytotoxicity studies presented here were performed in a tubular proximal original established porcine kidney cell line (LLC-PK1). We have compared cytotoxicity induced by different chemical cadmium forms in LLC-PK1 cells as a function of media cell culture pH and protein content. Cadmium stock solutions were prepared either by dissolving cadmium chloride or cadmium sulphate with increasing protein concentrations in the media cell culture. Its pH was monitored during experiments. Cytotoxicity was measured by neutral red uptake after 24 h of exposure. Dose-dependent cytotoxicity curves, calculated with REGTOX, were systematically correlated with pH and protein content. Experiments in vitro revealed that cadmium was dose-dependently toxic for LLC-PK1 for concentrations ranging from 10(-4) to 10(-6) M. We have noticed a lack of influence of the media cell culture pH on the cadmium cytotoxicity. REGTOX determines closely the EC50 values but EC50CdCl2 > EC50CdSO4 and cadmium have been assayed with an inductively coupled atomic emission spectrometer (ICP/AES) directly in the media cell culture and the cellular pellet. (C) 2001 Elsevier Science Ltd. All rights reserved.