CADMIUM DISTRIBUTION AND METALLOTHIONEIN IN THE LIVER OF MICE TREATED WITH PHENOBARBITAL

Abstract

It has been reported that phenobarbital produced a reduction in mortality in acute cadmium poisoning of mice and also remarkably accelerated cadmium ac-cumulation in the liver. In the present study, the cadmium distribution and metallothionein induction in the liver after injecting cadmium in mice treated with phenobarbital was examined. Phenobarbital concentrated cadmium in the super-natant fraction of the liver, but diminished it in the nuclei fraction. No difference in cadmium content was found in mitochondria and in microsome fractions between mice treated with and without phenobarbital. The amount of cadmium contained in metallothionein fractions in the liver increased slightly after cadmium injection in mice treated with phenobarbital, and only a trace amount of cadmium bound to metallothionein fraction in the liver was found when cadmium was added in vitro to a supernatant solution of the liver of mice treated with phenobarbital. When these results are compared with the results in rats pretreated with a small dose of cadmium, it is evident that metallothionein induction alone does not explain completely the acceleration of cadmium accumulation in the liver. The result of the present experiment suggests a mechanism other than induction of metallothi-onein to explain the effect of phenobarbital on cadmium distribution.