| Abstract: | The measurement of available Zn in rainbow trout hepatocytes exposed to a selection of heavy metals was evaluated as a potential end point for assessing heavy metal exposure. Induction of metallothionein, a well-known biomarker for heavy metal exposure, was also evaluated concurrently with available Zn measurements. Rainbow trout hepatocytes were exposed to several concentrations of copper, cadmium, mercury, silver, arsenite, and zinc salts for 48 h at 15°C. Hepatocytes were also exposed to industrial effluent from a metallurgy plant. After the exposure period, hepatocytes were analyzed for metallothionein (MT) and available Zn levels. The results showed that, with divalent metals, available Zn increased with MT levels; there was a significant correlation (R = 0,600; p = 0.0006) between the two. Moreover, the industrial effluent proved to be an inducer of available Zn in hepatocytes, as well as of MT. However, cells exposed to Ag responded with higher levels of available Zn before showing a corresponding MT induction in cells. Inversely, exposure to arsenite led to increased MT without any change in available Zn levels. The value for available Zn tended to be somewhat overestimated in the presence of metals such as Hg, and to a lesser extent Cd. The evaluation of available Zn, in addition to MT, appears to be a valid way of assessing exposure to mono- and divalent metals, though with arsenite, the MT induction response was higher than that of available Zn. The specificity of the available Zn biomarker for heavy metal exposure should be investigated more thoroughly for comparison with the MT biomarker. The measurement of available Zn holds promise as a new biomarker of heavy metal exposure. © 1996 by John Wiley & Sons, Inc. |
