DIFFERENTIAL CELL SENSITIVITY TO CADMIUM EXPOSURE IN RTGILL-W1, RTG-2, AND RTL-W1 RAINBOW TROUT (ONCORHYNCHUS MYKISS) CELL LINES: AN IN VITRO CELL LINE MODELTO STUDY CADMIUM-INDUCED CYTOTOXICITY.

Cadmium is intimately connected to Idaho through mining practices and other emissions of this toxic metal into the environment. Since aquatic organisms can serve as bioindicators to assess the possible impact of heavy metal contaminants, we used liver (AlLW1), gonadal (RTG-2), and gill (RTgiIl-W1) cell lines derived from rainbow trout to investigate cadmium-induced cytotoxicity. We hypothesize RTgill-W1 cells, which are frequently exposed to heavy metal contaminants, are more resistant to cadmium compared to RTL-W1 or RTG-2 cells. Cells were exposed to 200 pM or 500 pM cadmium chloride (CdCI2) for 0, 3, 12, 24 or 48 hours. Parameters assessed were cell morphology by phase-contrast microscopy, loss of adherence, and viability using a trypan blue exclusion assay. RTgill-W1 cells were more resistant to 200 pM CdCl2 compared to RTL-W1 and RTG-2 cells. When exposed to 500 μM CdCl2, RTgillWi remained more resistant (29.2 % viability), followed by RTG-2 (8.4% viability), and RTL-W1 cells (1.0% viability) at 48 hours. For comparison, we examined the effect of cadmium exposure on primary gill cells isolated from live rainbow trout to the lRTgill-W1 cell line. There was no difference in viability between RTgill-W1 and primary gill cells exposed to 200 pM CdCl2. When exposed to 500 pM CdCl2, primary gill cells were more resistant compared to RTgill-W1 cells. Collectively, RTgill-W1 and primary gill cells are more resistant to cadmium than RTL-W1 or RTG-2. This differential sensitivity to cadmium provides a model for elucidating the intracellular mechanisms by which cells respond to and protect against cadmium's toxic action. Furthermore, this research illustrates the importance of using multiple cell lines to access cytotoxicity in response to heavy metal contaminants. [ABSTRACT FROM AUTHOR]