Subcellular distribution of metallothionein and cadmium in the liver and kidneys of bank voles (Clethrionomys glareolus) exposed to dietary cadmium.

Metallothionein (MT) and cadmium (Cd) contents were determined in the subcellular fractions of the liver and kidneys of bank voles exposed for 6 weeks to elevated levels of dietary Cd-40 and 80 micrograms g-1 dry weight. Hepatic and renal MT was detected exclusively in the cytosol, while Cd was found in the cytosol (73-79% of the total content), nuclei (14-18%) and particulates (4-9%). The concentration of MT in the cytosol as well as Cd content in the particular subcellular fractions appeared to be a dose-dependent. The absence of MT in the nuclear and particulate fractions implied that Cd present in these compartments was not bound to the protein that is considered to provide protection against the toxic metal. Therefore, it is assumed that this component of intracellular Cd could be responsible for the histopathological changes that occurred in the liver (granuloma and focal hepatocyte swelling) and kidneys (focal degeneration of proximal tubules) of bank voles exposed to the higher level of dietary Cd.