Twenty-one male rabbits were divided into three groups: rabbits of two groups were given pelleted food containing
cadmium chloride at a dose level of 300 micrograms Cd/g over periods of 44 or 19 weeks. Rabbits of the last group were given ordinary commercial pelleted food and served as controls.
Cadmium increased urinary
protein and
amino acid by week 19 and increased it to a remarkably high level by week 44. After cessation of
cadmium exposure, rabbits of the first group (44 weeks exposure group) showed only little recovery from
cadmium health effects:
proteinuria and aminoaciduria were slightly improved. Depressed hepatic functions were also slightly improved, but did not return to the control level in 24 weeks. Fat and bone metabolism also remained depressed below the control level.
Anemia did not also readily recover. On the other hand, rabbits of the second group (19 weeks exposure) recovered from the effects of
cadmium:
proteinuria and aminoaciduria in most animals disappeared soon after the end of
cadmium exposure, plasma GPT fell after 1 week, and
hemoglobin and hematocrit returned to normal in 6-11 weeks. The above results show that after cessation of
cadmium exposure, mild
cadmium-induced health effects were reversible in a short period, while more severe effects were not readily reversible. High performance liquid chromatographic (HPLC) profiles of renal and hepatic
cadmium-thionein (Cd-MT) during and after exposure to
cadmium showed no correlation to the degree of
cadmium health effects, and therefore, did not help to elucidate mechanisms of the recovery from
cadmium-induced health effects, probably because
cadmium not bound with
metallothionein (non-MT-Cd) is responsible for inducing renal effects.