Ultrasound measurement of bone

The importance of photoperiod and ambient temperature on the accumulation of cadmium in the liver and kidneys of bank voles was determined in the present study. Males and females, aged 1 month, were given 3.0 micrograms Cd ml-1 drinking water and divided into four groups according to photoperiod (16 h light/8 h dark and 8 h light/16 h dark) and ambient temperature (20 or 5 degrees C); liver and kidneys were removed for cadmium as well as copper, iron and zinc analyses at the end of 6 weeks. Bank voles exposed to 5 degrees C in both photoperiods consumed approximately 30% less water containing cadmium than those kept at 20 degrees C. However, the total accumulation of cadmium in the liver and kidneys of males and females exposed to the low temperatures was 4.3-4.8 and 2.2-3.3 times less than that in animals maintained at room temperature in the long and short photoperiod, respectively. Simultaneously, the low temperature brought about an increase in the copper concentrations in the liver (12-43%) and kidneys (47-78%), giving rise to an inverse correlation between the cadmium accumulation and the tissue copper concentration. In contrast to cadmium and copper, the concentrations of iron and zinc were affected primarily by photoperiod. These findings indicate that ambient temperature is an important determinant of cadmium retention in the bank vole. It appears that low temperature decreases tissue cadmium accumulation not only by reducing cadmium intake but also through changes in copper metabolism.